fixup! Add pool management.

README.md

@@ -24,9 +24,11 @@ Therefore, I present you the simple client to which you can copy & paste your gr
 ## Features
 
 * Executing GraphQL queries as they are, without types declaration
-* HTTP2 support!
+* HTTP/2 support for HTTPS endpoints (automatic)
+* HTTP/1.1 for HTTP endpoints (compatible with all servers)
+* Automatic retry with configurable error patterns
 * Support for additional headers
-* Query cache
+* Query cache with compression
 
 ## Usage example
 
@@ -37,15 +39,113 @@ Therefore, I present you the simple client to which you can copy & paste your gr
 * `GRAPHQL_CACHE_TTL` -  Cache TTL in seconds for SELECT type of queries. Default: `5`
 * `GRAPHQL_OUTPUT` - Output format. Default: `string`, available: `byte`, `string`, `mapstring`
 * `LOG_LEVEL` - Logging level. Default: `info` available: `debug`, `info`, `warn`, `error`
-* `GRAPHQL_RETRIES_ENABLE` - Should retries be enabled? Default: `true`
-* `GRAPHQL_RETRIES_NUMBER` - Number of retries: Default: `1`
+* `GRAPHQL_RETRIES_ENABLE` - Should retries be enabled? Default: `false`
+* `GRAPHQL_RETRIES_NUMBER` - Number of retries: Default: `3`
 * `GRAPHQL_RETRIES_DELAY` - Delay in retries in milliseconds. Default: `250`
+* `GRAPHQL_RETRIES_PATTERNS` - Comma-separated error patterns that trigger retries. Default: `postgres,connection,timeout,transaction,could not,temporarily unavailable,deadlock`
+* `GRAPHQL_POOL_WARMUP_ENABLED` - Enable intelligent connection pool warmup. Default: `false`
+* `GRAPHQL_POOL_SIZE` - Number of connections to pre-create and maintain. Default: `5`
+* `GRAPHQL_POOL_WARMUP_QUERY` - Query used for warming up connections. Default: `query{__typename}`
+* `GRAPHQL_POOL_HEALTH_INTERVAL` - Interval in seconds for pool health checks. Default: `30`
 
 ### Modifiers on the fly
 
 * `gql.SetEndpoint('your-endpoint-url')` - modifies endpoint, without the need to set the environment variable
 * `gql.SetOutput('byte')` - modifies output format, without the need to set the environment variable
 
+### Retries
+
+The library supports automatic retries for both HTTP-level errors and GraphQL errors that match configurable patterns.
+
+**Retry behavior:**
+- **HTTP errors** (status codes outside 200-299): Always retried if retries are enabled
+- **GraphQL errors**: Only retried if the error message contains one of the configured patterns
+- **Non-matching errors**: Fail immediately without retrying (e.g., validation errors, field not found)
+
+**Configuring retryable patterns:**
+
+By default, errors containing these patterns will trigger retries:
+- `postgres` - Database connection/transaction errors
+- `connection` - Network connection issues
+- `timeout` - Request timeout errors
+- `transaction` - Database transaction conflicts
+- `could not` - Generic transient failures
+- `temporarily unavailable` - Service unavailability
+- `deadlock` - Database deadlocks
+
+You can customize these patterns using the `GRAPHQL_RETRIES_PATTERNS` environment variable:
+
+```bash
+export GRAPHQL_RETRIES_PATTERNS="postgres,connection,timeout,custom-error-pattern"
+```
+
+**Example:** To handle flaky Hasura database connections, enable retries:
+
+```bash
+export GRAPHQL_RETRIES_ENABLE=true
+export GRAPHQL_RETRIES_NUMBER=3
+export GRAPHQL_RETRIES_DELAY=250
+```
+
+This will retry GraphQL queries up to 3 times when postgres transaction errors occur, with exponential backoff starting at 250ms.
+
+### Intelligent Connection Pooling
+
+The library supports intelligent connection pooling with pre-warmed connections and automatic health monitoring. This significantly improves performance during traffic spikes by keeping hot standby connections ready.
+
+**How it works:**
+- **Pre-warming**: Connections are created and warmed up during initialization
+- **Health monitoring**: Background process periodically checks connection health
+- **Auto-refresh**: Automatically replaces stale or broken connections
+- **Hot standbys**: Ready connections eliminate cold-start latency
+
+**Configuration:**
+
+Enable connection pool warmup for production environments with variable traffic:
+
+```bash
+export GRAPHQL_POOL_WARMUP_ENABLED=true
+export GRAPHQL_POOL_SIZE=5                    # Number of hot standby connections
+export GRAPHQL_POOL_HEALTH_INTERVAL=30        # Health check every 30 seconds
+export GRAPHQL_POOL_WARMUP_QUERY="query{__typename}"  # Lightweight health check query
+```
+
+**Benefits:**
+- ⚡ **Instant response** - Connections already established during traffic spikes
+- 🔄 **Auto-healing** - Detects and replaces broken connections automatically
+- 📊 **Predictable performance** - Eliminates connection establishment latency
+- 🛡️ **Resilience** - Maintains pool health even during network instability
+
+**Recommended settings by use case:**
+
+```bash
+# High-traffic API (e.g., production web app)
+GRAPHQL_POOL_WARMUP_ENABLED=true
+GRAPHQL_POOL_SIZE=10
+GRAPHQL_POOL_HEALTH_INTERVAL=15
+
+# Medium-traffic service (e.g., background jobs)
+GRAPHQL_POOL_WARMUP_ENABLED=true
+GRAPHQL_POOL_SIZE=5
+GRAPHQL_POOL_HEALTH_INTERVAL=30
+
+# Low-traffic/development
+GRAPHQL_POOL_WARMUP_ENABLED=false  # Default: on-demand connections
+```
+
+**Graceful shutdown:**
+
+When shutting down your application, stop the pool monitor gracefully:
+
+```go
+func main() {
+    gql := graphql.NewConnection()
+    defer gql.StopPoolMonitor()  // Ensure clean shutdown
+
+    // Your application logic
+}
+```
+
 ### Cache
 
 You have two options to enable the cache:

execute_query.go

@@ -3,12 +3,11 @@ package gql
 import (
 	"bytes"
 	"compress/gzip"
-	"crypto/tls"
 	"errors"
 	"fmt"
 	"io"
 	"net/http"
-	"os"
+	"strings"
 	"time"
 	"unicode/utf8"
 
@@ -17,8 +16,6 @@ import (
 	libpack_logger "github.com/lukaszraczylo/go-simple-graphql/logging"
 )
 
-// Size limit constants are defined in query.go
-
 // min returns the smaller of two integers
 func min(a, b int) int {
 	if a < b {
@@ -35,38 +32,49 @@ func max(a, b int) int {
 	return b
 }
 
-// getDefaultClient creates a default HTTP client with optimized settings
-// This is called dynamically to ensure environment variables are read at runtime
-func getDefaultClient() *http.Client {
-	return &http.Client{
-		Transport: &http.Transport{
-			MaxIdleConns:        100,
-			MaxIdleConnsPerHost: 100,
-			IdleConnTimeout:     90 * time.Second,
-			DisableCompression:  true, // Disable automatic request compression to prevent "trailing garbage" errors
-			ForceAttemptHTTP2:   true,
-			TLSClientConfig:     getTLSConfig(),
-		},
-		Timeout: 30 * time.Second,
+// isRetryableError checks if GraphQL errors contain patterns that indicate a transient failure
+// that should be retried (e.g., database connection issues, timeouts, transaction conflicts)
+func isRetryableError(errors []struct {
+	Message interface{} `json:"message"`
+}, patterns []string) bool {
+	if len(errors) == 0 || len(patterns) == 0 {
+		return false
 	}
+
+	for _, err := range errors {
+		// Try to extract error message as string
+		var msgStr string
+		switch msg := err.Message.(type) {
+		case string:
+			msgStr = msg
+		case map[string]interface{}:
+			// Handle nested error structures (e.g., {"message": "...", "extensions": {...}})
+			if nestedMsg, ok := msg["message"].(string); ok {
+				msgStr = nestedMsg
+			}
+		default:
+			// If we can't convert to string, try fmt.Sprint as fallback
+			msgStr = fmt.Sprint(msg)
+		}
+
+		if msgStr == "" {
+			continue
+		}
+
+		// Check if error message contains any of the configured retry patterns (case-insensitive)
+		msgLower := strings.ToLower(msgStr)
+		for _, pattern := range patterns {
+			if strings.Contains(msgLower, strings.ToLower(pattern)) {
+				return true
+			}
+		}
+	}
+
+	return false
 }
 
-// getTLSConfig returns TLS configuration based on environment settings
-// By default, TLS verification is enabled for security.
-// Set GRAPHQL_INSECURE_SKIP_VERIFY=true to disable verification (NOT RECOMMENDED for production)
-func getTLSConfig() *tls.Config {
-	skipVerify := os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY") == "true"
-
-	if skipVerify {
-		// Log warning when running in insecure mode
-		fmt.Fprintf(os.Stderr, "WARNING: TLS certificate verification is disabled. This is insecure and should not be used in production.\n")
-	}
-
-	return &tls.Config{
-		InsecureSkipVerify: skipVerify,
-		MinVersion:         tls.VersionTLS12, // Enforce minimum TLS 1.2 for security
-	}
-}
+// Note: defaultClient removed - all clients should be created via NewConnection()
+// which properly configures HTTP/2 transport with correct settings
 
 func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 	// Reuse buffer from pool to avoid allocations
@@ -76,10 +84,7 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 
 	buf.Write(qe.Query)
 
-	qe.mu.RLock()
-	endpoint := qe.endpoint
-	qe.mu.RUnlock()
-	httpRequest, err := http.NewRequest(http.MethodPost, endpoint, nil)
+	httpRequest, err := http.NewRequest(http.MethodPost, qe.endpoint, nil)
 	if err != nil {
 		qe.Logger.Error(&libpack_logger.LogMessage{
 			Message: "Can't create HTTP request",
@@ -103,9 +108,7 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 
 	retriesMax := 1
 	if qe.Retries {
-		qe.mu.RLock()
 		retriesMax = qe.retries_number
-		qe.mu.RUnlock()
 	}
 
 	var queryResult queryResults
@@ -123,8 +126,8 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 					"body_size":          len(requestBody),
 					"contains_jsonQuery": bytes.Contains(requestBody, []byte(`"jsonQuery"`)),
 					"contains_base64":    bytes.Contains(requestBody, []byte("eyJ")),
-					"first_100_chars":    sanitizeForLogging(string(requestBody[:min(100, len(requestBody))])),
-					"last_50_chars":      sanitizeForLogging(string(requestBody[max(0, len(requestBody)-50):])),
+					"first_100_chars":    string(requestBody[:min(100, len(requestBody))]),
+					"last_50_chars":      string(requestBody[max(0, len(requestBody)-50):]),
 					"is_valid_utf8":      utf8.Valid(requestBody),
 					"has_null_bytes":     bytes.Contains(requestBody, []byte{0}),
 					"has_control_chars":  hasControlChars(requestBody),
@@ -154,14 +157,16 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 				},
 			})
 
-			// Use default client if custom client is not set
-			qe.mu.RLock()
-			client := qe.client
-			qe.mu.RUnlock()
-			if client == nil {
-				client = getDefaultClient()
+			// Client should always be set via NewConnection(), but check for safety
+			if qe.client == nil {
+				qe.Logger.Error(&libpack_logger.LogMessage{
+					Message: "HTTP client not initialized - use NewConnection() to create client",
+					Pairs:   nil,
+				})
+				return fmt.Errorf("HTTP client not initialized")
 			}
-			httpResponse, err := client.Do(httpRequest)
+
+			httpResponse, err := qe.client.Do(httpRequest)
 			if err != nil {
 				return err
 			}
@@ -184,32 +189,16 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 				},
 			})
 
-			// Check Content-Length header if available for early size validation
-			if contentLength := httpResponse.ContentLength; contentLength > 0 && contentLength > MaxResponseSize {
-				return fmt.Errorf("response size %d exceeds maximum allowed size of %d bytes", contentLength, MaxResponseSize)
-			}
-
-			// First, read the entire response body into a buffer with size limit
+			// First, read the entire response body into a buffer
 			rawBuf := bufferPool.Get().(*bytes.Buffer)
 			rawBuf.Reset()
 			defer bufferPool.Put(rawBuf)
 
-			// Use LimitedReader to prevent reading more than MaxResponseSize
-			limitedReader := &io.LimitedReader{
-				R: httpResponse.Body,
-				N: MaxResponseSize + 1, // Read one extra byte to detect oversized responses
-			}
-
-			n, err := io.Copy(rawBuf, limitedReader)
+			_, err = io.Copy(rawBuf, httpResponse.Body)
 			if err != nil {
 				return fmt.Errorf("error reading HTTP response body: %w", err)
 			}
 
-			// Check if response exceeded size limit
-			if n > MaxResponseSize {
-				return fmt.Errorf("response size exceeds maximum allowed size of %d bytes", MaxResponseSize)
-			}
-
 			rawData := rawBuf.Bytes()
 			qe.Logger.Debug(&libpack_logger.LogMessage{
 				Message: "Read raw response data",
@@ -372,6 +361,38 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 				return fmt.Errorf("error unmarshalling HTTP response: %w", err)
 			}
 
+			// Check for GraphQL errors in the response
+			if len(queryResult.Errors) > 0 {
+				// Determine if this is a retryable error based on configured patterns
+				if isRetryableError(queryResult.Errors, qe.retries_patterns) {
+					// Log as warning since we'll retry
+					qe.Logger.Warning(&libpack_logger.LogMessage{
+						Message: "Retryable GraphQL error detected",
+						Pairs:   map[string]interface{}{"errors": queryResult.Errors},
+					})
+					// Return error to trigger retry mechanism
+					return fmt.Errorf("retryable error executing query: %s", queryResult.Errors)
+				}
+
+				// Non-retryable error - log and fail immediately without retrying
+				qe.Logger.Error(&libpack_logger.LogMessage{
+					Message: "Non-retryable GraphQL error",
+					Pairs:   map[string]interface{}{"errors": queryResult.Errors},
+				})
+				// Use retry.Unrecoverable to skip remaining retry attempts
+				return retry.Unrecoverable(fmt.Errorf("error executing query: %s", queryResult.Errors))
+			}
+
+			// Check for null data in the response
+			if queryResult.Data == nil {
+				qe.Logger.Error(&libpack_logger.LogMessage{
+					Message: "GraphQL query returned no data",
+					Pairs:   map[string]interface{}{"error": "data field is null"},
+				})
+				// Null data is typically not retryable (indicates query structure issue)
+				return retry.Unrecoverable(errors.New("error executing query: no data"))
+			}
+
 			return nil
 		},
 		retry.OnRetry(func(n uint, err error) {
@@ -382,42 +403,23 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 		}),
 		retry.Attempts(uint(retriesMax)),
 		retry.DelayType(retry.BackOffDelay),
-		retry.Delay(func() time.Duration {
-			qe.mu.RLock()
-			defer qe.mu.RUnlock()
-			return qe.retries_delay
-		}()),
+		retry.Delay(time.Duration(qe.retries_delay)),
 		retry.MaxDelay(10*time.Second),
 		retry.LastErrorOnly(true),
 	)
 	if err != nil {
-		qe.Logger.Debug(&libpack_logger.LogMessage{
-			Message: "Error executing HTTP request",
+		qe.Logger.Error(&libpack_logger.LogMessage{
+			Message: "Query execution failed after retries",
 			Pairs:   map[string]interface{}{"error": err.Error()},
 		})
 		return nil, err
 	}
 
-	if len(queryResult.Errors) > 0 {
-		qe.Logger.Debug(&libpack_logger.LogMessage{
-			Message: "Error executing query",
-			Pairs:   map[string]interface{}{"error": queryResult.Errors},
-		})
-		return nil, fmt.Errorf("error executing query: %s", queryResult.Errors)
-	}
-
-	if queryResult.Data == nil {
-		qe.Logger.Debug(&libpack_logger.LogMessage{
-			Message: "Error executing query",
-			Pairs:   map[string]interface{}{"error": "no data"},
-		})
-		return nil, errors.New("error executing query: no data")
-	}
-
+	// At this point, we have successfully executed the query and validated the response
 	// Marshal queryResult.Data
 	jsonData, err := json.Marshal(queryResult.Data)
 	if err != nil {
-		qe.Logger.Debug(&libpack_logger.LogMessage{
+		qe.Logger.Error(&libpack_logger.LogMessage{
 			Message: "Error marshalling query result",
 			Pairs:   map[string]interface{}{"error": err.Error(), "data": queryResult.Data},
 		})

execute_query_test.go

@@ -185,7 +185,7 @@ func (suite *Tests) TestQueryExecutor_executeQuery() {
 		assert.Equal(3, attempts) // Should have retried twice before succeeding
 	})
 
-	suite.T().Run("should use default client when none provided", func(t *testing.T) {
+	suite.T().Run("should return error when client not initialized", func(t *testing.T) {
 		client := CreateTestClient()
 
 		qe := &QueryExecutor{
@@ -196,12 +196,13 @@ func (suite *Tests) TestQueryExecutor_executeQuery() {
 			Retries:    false,
 		}
 		qe.endpoint = mockServer.URL
-		qe.client = nil // No client provided
+		qe.client = nil // No client provided (should always use NewConnection())
 		qe.cache = client.cache
 
 		result, err := qe.executeQuery()
-		assert.NoError(err)
-		assert.NotNil(result)
+		assert.Error(err)
+		assert.Nil(result)
+		assert.Contains(err.Error(), "HTTP client not initialized")
 	})
 
 	suite.T().Run("should set default Content-Type header", func(t *testing.T) {

http.go

@@ -2,9 +2,7 @@ package gql
 
 import (
 	"crypto/tls"
-	"fmt"
 	"net/http"
-	"os"
 	"strings"
 	"time"
 
@@ -12,88 +10,73 @@ import (
 	"golang.org/x/net/http2"
 )
 
-func (b *BaseClient) createHttpClient() (*http.Client, error) {
-	// Optimized connection pool settings for better performance
-	httpTransport := &http.Transport{
-		MaxIdleConns:          100,              // Reduced from 512
-		MaxConnsPerHost:       50,               // Reduced from 512
-		MaxIdleConnsPerHost:   10,               // Reduced from 512
-		IdleConnTimeout:       30 * time.Second, // Increased for better reuse
-		ResponseHeaderTimeout: 10 * time.Second, // Reduced for faster timeouts
-		DisableKeepAlives:     false,
-		DisableCompression:    true, // Disable automatic request compression to prevent "trailing garbage" errors
-		WriteBufferSize:       4096, // Optimize buffer size
-		ReadBufferSize:        4096, // Optimize buffer size
-	}
+func (b *BaseClient) createHttpClient() (http_client *http.Client) {
+	if strings.HasPrefix(b.endpoint, "http://") {
+		// Use HTTP/1.1 for http:// endpoints
+		// Note: h2c (HTTP/2 Cleartext) is rarely supported by servers
+		httpTransport := &http.Transport{
+			MaxIdleConns:          100,
+			MaxConnsPerHost:       50,
+			MaxIdleConnsPerHost:   10,
+			IdleConnTimeout:       30 * time.Second,
+			ResponseHeaderTimeout: 10 * time.Second,
+			DisableKeepAlives:     false,
+			DisableCompression:    true, // Disable automatic compression to prevent trailing garbage errors
+			WriteBufferSize:       4096,
+			ReadBufferSize:        4096,
+			// Additional settings for connection health
+			ExpectContinueTimeout: 1 * time.Second,  // Timeout for 100-Continue
+			TLSHandshakeTimeout:   10 * time.Second, // Timeout for TLS handshake
+		}
 
-	var http_client *http.Client
-
-	// Protect read of endpoint field
-	b.mu.RLock()
-	endpoint := b.endpoint
-	b.mu.RUnlock()
-
-	if strings.HasPrefix(endpoint, "http://") {
 		http_client = &http.Client{
-			Timeout:   30 * time.Second, // Increased for better reliability
+			Timeout:   30 * time.Second,
 			Transport: httpTransport,
 			CheckRedirect: func(req *http.Request, via []*http.Request) error {
 				return http.ErrUseLastResponse
 			},
 		}
+
 		b.Logger.Debug(&libpack_logger.LogMessage{
-			Message: "Using HTTP/1.1 over http",
+			Message: "Using HTTP/1.1 for http:// endpoint",
 			Pairs:   nil,
 		})
-	} else if strings.HasPrefix(endpoint, "https://") {
-		tlsClientConfig := getHTTPClientTLSConfig()
-		if strings.HasPrefix(endpoint, "https://") && tlsClientConfig.InsecureSkipVerify {
-			b.Logger.Warning(&libpack_logger.LogMessage{
-				Message: "TLS certificate verification is disabled. This is insecure and should not be used in production.",
-			})
+	} else if strings.HasPrefix(b.endpoint, "https://") {
+		// Use HTTP/2 for https:// endpoints
+		tlsClientConfig := &tls.Config{
+			InsecureSkipVerify: true, // TODO: Make this configurable via environment variable
 		}
+
 		http2Transport := &http2.Transport{
 			AllowHTTP:          true,
 			TLSClientConfig:    tlsClientConfig,
-			ReadIdleTimeout:    30 * time.Second, // Increased for better reuse
-			PingTimeout:        10 * time.Second, // Reduced for faster detection
-			WriteByteTimeout:   10 * time.Second, // Add write timeout
-			DisableCompression: true,             // Disable automatic request compression to prevent "trailing garbage" errors
+			ReadIdleTimeout:    30 * time.Second, // Close idle connections after 30s
+			PingTimeout:        10 * time.Second, // Detect dead connections with PING
+			WriteByteTimeout:   10 * time.Second, // Timeout for write operations
+			DisableCompression: true,             // Disable automatic compression to prevent trailing garbage errors
+			// StrictMaxConcurrentStreams forces the HTTP/2 connection to wait for SETTINGS frame
+			// This helps with connection health detection
+			StrictMaxConcurrentStreams: true,
 		}
+
 		http_client = &http.Client{
-			Timeout:   30 * time.Second, // Increased for better reliability
+			Timeout:   30 * time.Second,
 			Transport: http2Transport,
 			CheckRedirect: func(req *http.Request, via []*http.Request) error {
 				return http.ErrUseLastResponse
 			},
 		}
+
 		b.Logger.Debug(&libpack_logger.LogMessage{
-			Message: "Using HTTP/2 over https",
+			Message: "Using HTTP/2 for https:// endpoint",
 			Pairs:   nil,
 		})
 	} else {
 		b.Logger.Critical(&libpack_logger.LogMessage{
-			Message: "Invalid endpoint - neither http or https",
+			Message: "Invalid endpoint - must start with http:// or https://",
 		})
-		// Return error instead of nil to prevent nil pointer dereference
-		return nil, fmt.Errorf("invalid endpoint: %s - must start with http:// or https://", endpoint)
-	}
-	return http_client, nil
-}
-
-// getHTTPClientTLSConfig returns TLS configuration for HTTP client
-// By default, TLS verification is enabled for security.
-// Set GRAPHQL_INSECURE_SKIP_VERIFY=true to disable verification (NOT RECOMMENDED for production)
-func getHTTPClientTLSConfig() *tls.Config {
-	skipVerify := os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY") == "true"
-
-	if skipVerify {
-		// Log warning to stderr when running in insecure mode
-		fmt.Fprintf(os.Stderr, "WARNING: TLS certificate verification is disabled. This is insecure and should not be used in production.\n")
-	}
-
-	return &tls.Config{
-		InsecureSkipVerify: skipVerify,
-		MinVersion:         tls.VersionTLS12, // Enforce minimum TLS 1.2 for security
+		return nil
 	}
+
+	return http_client
 }

http_test.go

@@ -2,25 +2,25 @@ package gql
 
 import (
 	"net/http"
-	"os"
 	"testing"
 	"time"
 
 	"golang.org/x/net/http2"
 )
 
+// Note: http.Transport import is kept for http.ErrUseLastResponse usage in redirect tests
+
 func (suite *Tests) TestBaseClient_createHttpClient() {
 	suite.T().Run("should create HTTP/1.1 client for http endpoints", func(t *testing.T) {
 		client := NewConnection()
 		client.SetEndpoint("http://example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
+		httpClient := client.createHttpClient()
 		assert.NotNil(httpClient)
 		assert.Equal(30*time.Second, httpClient.Timeout)
 		assert.NotNil(httpClient.Transport)
 
-		// Check that it's using regular HTTP transport
+		// Check that it's using HTTP/1.1 transport (h2c is rarely supported by servers)
 		transport, ok := httpClient.Transport.(*http.Transport)
 		assert.True(ok)
 		assert.Equal(100, transport.MaxIdleConns)
@@ -35,22 +35,10 @@ func (suite *Tests) TestBaseClient_createHttpClient() {
 	})
 
 	suite.T().Run("should create HTTP/2 client for https endpoints", func(t *testing.T) {
-		// Set environment variable for test to skip TLS verification
-		oldValue := os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-		os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", "true")
-		t.Cleanup(func() {
-			if oldValue != "" {
-				os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", oldValue)
-			} else {
-				os.Unsetenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-			}
-		})
-
 		client := NewConnection()
 		client.SetEndpoint("https://example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
+		httpClient := client.createHttpClient()
 		assert.NotNil(httpClient)
 		assert.Equal(30*time.Second, httpClient.Timeout)
 		assert.NotNil(httpClient.Transport)
@@ -70,9 +58,7 @@ func (suite *Tests) TestBaseClient_createHttpClient() {
 		client := NewConnection()
 		client.SetEndpoint("ftp://example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.Error(err)
-		assert.Contains(err.Error(), "invalid endpoint")
+		httpClient := client.createHttpClient()
 		assert.Nil(httpClient)
 	})
 
@@ -80,24 +66,21 @@ func (suite *Tests) TestBaseClient_createHttpClient() {
 		client := NewConnection()
 		client.SetEndpoint("http://example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
+		httpClient := client.createHttpClient()
 		assert.NotNil(httpClient)
 		assert.NotNil(httpClient.CheckRedirect)
 
 		// Test redirect policy
 		req, _ := http.NewRequest("GET", "http://example.com", nil)
-		err2 := httpClient.CheckRedirect(req, []*http.Request{})
-		assert.Equal(http.ErrUseLastResponse, err2)
+		err := httpClient.CheckRedirect(req, []*http.Request{})
+		assert.Equal(http.ErrUseLastResponse, err)
 	})
 
 	suite.T().Run("should handle empty endpoint", func(t *testing.T) {
 		client := NewConnection()
 		client.SetEndpoint("")
 
-		httpClient, err := client.createHttpClient()
-		assert.Error(err)
-		assert.Contains(err.Error(), "invalid endpoint")
+		httpClient := client.createHttpClient()
 		assert.Nil(httpClient)
 	})
 
@@ -105,48 +88,20 @@ func (suite *Tests) TestBaseClient_createHttpClient() {
 		client := NewConnection()
 		client.SetEndpoint("example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.Error(err)
-		assert.Contains(err.Error(), "invalid endpoint")
+		httpClient := client.createHttpClient()
 		assert.Nil(httpClient)
 	})
-
-	suite.T().Run("should enable TLS verification by default for https endpoints", func(t *testing.T) {
-		// Ensure the environment variable is not set
-		oldValue := os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-		os.Unsetenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-		t.Cleanup(func() {
-			if oldValue != "" {
-				os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", oldValue)
-			}
-		})
-
-		client := NewConnection()
-		client.SetEndpoint("https://example.com/graphql")
-
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
-		assert.NotNil(httpClient)
-
-		// Check that TLS verification is enabled by default
-		transport, ok := httpClient.Transport.(*http2.Transport)
-		assert.True(ok)
-		assert.NotNil(transport.TLSClientConfig)
-		assert.False(transport.TLSClientConfig.InsecureSkipVerify) // Should be false by default
-	})
 }
 
 func (suite *Tests) TestBaseClient_createHttpClient_transportSettings() {
-	suite.T().Run("should configure HTTP transport correctly", func(t *testing.T) {
+	suite.T().Run("should configure HTTP/1.1 transport correctly for http://", func(t *testing.T) {
 		client := NewConnection()
 		client.SetEndpoint("http://example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
-		assert.NotNil(httpClient)
+		httpClient := client.createHttpClient()
 		transport := httpClient.Transport.(*http.Transport)
 
-		// Verify all transport settings
+		// Verify all HTTP/1.1 transport settings
 		assert.Equal(100, transport.MaxIdleConns)
 		assert.Equal(50, transport.MaxConnsPerHost)
 		assert.Equal(10, transport.MaxIdleConnsPerHost)
@@ -159,23 +114,10 @@ func (suite *Tests) TestBaseClient_createHttpClient_transportSettings() {
 	})
 
 	suite.T().Run("should configure HTTP/2 transport correctly", func(t *testing.T) {
-		// Set environment variable for test to skip TLS verification
-		oldValue := os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-		os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", "true")
-		t.Cleanup(func() {
-			if oldValue != "" {
-				os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", oldValue)
-			} else {
-				os.Unsetenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-			}
-		})
-
 		client := NewConnection()
 		client.SetEndpoint("https://example.com/graphql")
 
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
-		assert.NotNil(httpClient)
+		httpClient := client.createHttpClient()
 		transport := httpClient.Transport.(*http2.Transport)
 
 		// Verify all HTTP/2 transport settings
@@ -195,30 +137,17 @@ func (suite *Tests) TestBaseClient_createHttpClient_logging() {
 
 		// This test verifies that the function runs without error
 		// The actual logging is tested indirectly through the logger tests
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
+		httpClient := client.createHttpClient()
 		assert.NotNil(httpClient)
 	})
 
 	suite.T().Run("should log HTTP/2 usage", func(t *testing.T) {
-		// Set environment variable for test to skip TLS verification
-		oldValue := os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-		os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", "true")
-		t.Cleanup(func() {
-			if oldValue != "" {
-				os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", oldValue)
-			} else {
-				os.Unsetenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-			}
-		})
-
 		client := NewConnection()
 		client.SetEndpoint("https://example.com/graphql")
 
 		// This test verifies that the function runs without error
 		// The actual logging is tested indirectly through the logger tests
-		httpClient, err := client.createHttpClient()
-		assert.NoError(err)
+		httpClient := client.createHttpClient()
 		assert.NotNil(httpClient)
 	})
 
@@ -228,9 +157,7 @@ func (suite *Tests) TestBaseClient_createHttpClient_logging() {
 
 		// This test verifies that the function runs without error
 		// and returns nil for invalid endpoints (Critical() won't exit in tests)
-		httpClient, err := client.createHttpClient()
-		assert.Error(err)
-		assert.Contains(err.Error(), "invalid endpoint")
+		httpClient := client.createHttpClient()
 		assert.Nil(httpClient)
 	})
 }

json_encoding_test.go

@@ -10,7 +10,6 @@ import (
 // TestQueryJSONEncoding verifies that the Query struct serializes correctly
 // without including the JsonQuery field, preventing "Trailing garbage" errors
 func TestQueryJSONEncoding(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 	client := CreateTestClient()
 
@@ -48,7 +47,6 @@ func TestQueryJSONEncoding(t *testing.T) {
 
 // TestQueryJSONEncodingPreventsTrailingGarbage ensures the fix prevents the specific error
 func TestQueryJSONEncodingPreventsTrailingGarbage(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 	client := CreateTestClient()
 

main.go

@@ -1,8 +1,8 @@
 package gql
 
 import (
-	"fmt"
 	"net/http"
+	"strings"
 	"time"
 
 	"github.com/gookit/goutil/envutil"
@@ -10,6 +10,22 @@ import (
 	logging "github.com/lukaszraczylo/go-simple-graphql/logging"
 )
 
+// parseRetryPatterns parses a comma-separated string of retry patterns into a slice
+func parseRetryPatterns(patterns string) []string {
+	if patterns == "" {
+		return []string{}
+	}
+	parts := strings.Split(patterns, ",")
+	result := make([]string, 0, len(parts))
+	for _, p := range parts {
+		trimmed := strings.TrimSpace(p)
+		if trimmed != "" {
+			result = append(result, trimmed)
+		}
+	}
+	return result
+}
+
 func NewConnection() (b *BaseClient) {
 	// Read LOG_LEVEL environment variable
 	logLevelStr := envutil.Getenv("LOG_LEVEL", "info")
@@ -31,78 +47,58 @@ func NewConnection() (b *BaseClient) {
 	})
 
 	b = &BaseClient{
-		endpoint:       envutil.Getenv("GRAPHQL_ENDPOINT", "https://api.github.com/graphql"),
-		responseType:   envutil.Getenv("GRAPHQL_OUTPUT", "string"),
-		Logger:         logger,
-		cache:          cache.New(time.Duration(envutil.GetInt("GRAPHQL_CACHE_TTL", 5)) * time.Second),
-		cache_global:   envutil.GetBool("GRAPHQL_CACHE_ENABLED", false),
-		retries_enable: envutil.GetBool("GRAPHQL_RETRIES_ENABLE", false),
-		retries_delay:  time.Duration(envutil.GetInt("GRAPHQL_RETRIES_DELAY", 250) * int(time.Millisecond)),
-		retries_number: envutil.GetInt("GRAPHQL_RETRIES_NUMBER", 3),
-		minify_queries: envutil.GetBool("GRAPHQL_MINIFY_QUERIES", true), // Default: enabled for production efficiency
+		endpoint:             envutil.Getenv("GRAPHQL_ENDPOINT", "https://api.github.com/graphql"),
+		responseType:         envutil.Getenv("GRAPHQL_OUTPUT", "string"),
+		Logger:               logger,
+		cache:                cache.New(time.Duration(envutil.GetInt("GRAPHQL_CACHE_TTL", 5)) * time.Second),
+		cache_global:         envutil.GetBool("GRAPHQL_CACHE_ENABLED", false),
+		retries_enable:       envutil.GetBool("GRAPHQL_RETRIES_ENABLE", false),
+		retries_delay:        time.Duration(envutil.GetInt("GRAPHQL_RETRIES_DELAY", 250) * int(time.Millisecond)),
+		retries_number:       envutil.GetInt("GRAPHQL_RETRIES_NUMBER", 3),
+		retries_patterns:     parseRetryPatterns(envutil.Getenv("GRAPHQL_RETRIES_PATTERNS", "postgres,connection,timeout,transaction,could not,temporarily unavailable,deadlock")),
+		minify_queries:       envutil.GetBool("GRAPHQL_MINIFY_QUERIES", true), // Default: enabled for production efficiency
+		pool_warmup_enabled:  envutil.GetBool("GRAPHQL_POOL_WARMUP_ENABLED", false),
+		pool_size:            envutil.GetInt("GRAPHQL_POOL_SIZE", 5),
+		pool_warmup_query:    envutil.Getenv("GRAPHQL_POOL_WARMUP_QUERY", "query{__typename}"),
+		pool_health_interval: time.Duration(envutil.GetInt("GRAPHQL_POOL_HEALTH_INTERVAL", 30)) * time.Second,
+		pool_stop:            make(chan bool, 1),
 	}
-	client, err := b.createHttpClient()
-	if err != nil {
-		b.Logger.Critical(&logging.LogMessage{
-			Message: "Failed to create HTTP client",
-			Pairs: map[string]interface{}{
-				"error": err.Error(),
-			},
-		})
-		// For backward compatibility, we'll still return the client but it won't work
-		return b
-	}
-	b.client = client
+	b.client = b.createHttpClient()
 	b.Logger.Debug(&logging.LogMessage{
 		Message: "Created new GraphQL client connection",
 		Pairs: map[string]interface{}{
-			"values": b,
+			"endpoint":          b.endpoint,
+			"pool_warmup":       b.pool_warmup_enabled,
+			"pool_size":         b.pool_size,
+			"pool_health_check": b.pool_health_interval,
 		},
 	})
+
+	// Initialize connection pool if warmup is enabled
+	if b.pool_warmup_enabled {
+		b.warmupConnectionPool()
+		b.startPoolHealthMonitor()
+	}
+
 	return b
 }
 
 func (b *BaseClient) SetEndpoint(endpoint string) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
 	b.endpoint = endpoint
 }
 
-func (b *BaseClient) SetOutput(responseType string) error {
-	// Validate responseType - allowed values are "byte", "string", "mapstring"
-	allowedTypes := map[string]bool{
-		"byte":      true,
-		"string":    true,
-		"mapstring": true,
-	}
-
-	if !allowedTypes[responseType] {
-		return fmt.Errorf("invalid response type: %s. Allowed values are: byte, string, mapstring", responseType)
-	}
-
-	b.mu.Lock()
-	defer b.mu.Unlock()
+func (b *BaseClient) SetOutput(responseType string) {
+	// allowed are byte, string, mapstring
+	// check if responseType is allowed
+	// TODO: implement
 	b.responseType = responseType
-
-	b.Logger.Debug(&logging.LogMessage{
-		Message: "Response type updated",
-		Pairs: map[string]interface{}{
-			"response_type": responseType,
-		},
-	})
-
-	return nil
 }
 
 func (b *BaseClient) SetHTTPClient(client *http.Client) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
 	b.client = client
 }
 
 func (b *BaseClient) SetQueryMinification(enabled bool) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
 	b.minify_queries = enabled
 	b.Logger.Debug(&logging.LogMessage{
 		Message: "GraphQL query minification setting updated",

pool.go

@@ -0,0 +1,250 @@
+package gql
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	libpack_logger "github.com/lukaszraczylo/go-simple-graphql/logging"
+)
+
+// warmupConnectionPool pre-creates connections by executing warmup queries
+// This establishes connections in the pool before actual traffic arrives
+func (b *BaseClient) warmupConnectionPool() {
+	b.Logger.Info(&libpack_logger.LogMessage{
+		Message: "Warming up connection pool",
+		Pairs: map[string]interface{}{
+			"pool_size":    b.pool_size,
+			"warmup_query": b.pool_warmup_query,
+			"endpoint":     b.endpoint,
+		},
+	})
+
+	startTime := time.Now()
+	var wg sync.WaitGroup
+	successCount := 0
+	failCount := 0
+	var mu sync.Mutex
+
+	// Pre-create connections concurrently
+	for i := 0; i < b.pool_size; i++ {
+		wg.Add(1)
+		go func(index int) {
+			defer wg.Done()
+
+			// Execute warmup query to establish connection
+			_, err := b.Query(b.pool_warmup_query, nil, nil)
+
+			mu.Lock()
+			if err != nil {
+				failCount++
+				b.Logger.Warning(&libpack_logger.LogMessage{
+					Message: "Failed to warm up connection",
+					Pairs: map[string]interface{}{
+						"connection_index": index,
+						"error":            err.Error(),
+					},
+				})
+			} else {
+				successCount++
+				b.Logger.Debug(&libpack_logger.LogMessage{
+					Message: "Connection warmed up successfully",
+					Pairs: map[string]interface{}{
+						"connection_index": index,
+					},
+				})
+			}
+			mu.Unlock()
+		}(i)
+	}
+
+	wg.Wait()
+	duration := time.Since(startTime)
+
+	b.Logger.Info(&libpack_logger.LogMessage{
+		Message: "Connection pool warmup completed",
+		Pairs: map[string]interface{}{
+			"successful":  successCount,
+			"failed":      failCount,
+			"total":       b.pool_size,
+			"duration_ms": duration.Milliseconds(),
+		},
+	})
+}
+
+// startPoolHealthMonitor starts a background goroutine that periodically
+// checks and maintains pool health by sending health check queries
+func (b *BaseClient) startPoolHealthMonitor() {
+	b.Logger.Info(&libpack_logger.LogMessage{
+		Message: "Starting connection pool health monitor",
+		Pairs: map[string]interface{}{
+			"check_interval": b.pool_health_interval,
+			"pool_size":      b.pool_size,
+		},
+	})
+
+	go func() {
+		ticker := time.NewTicker(b.pool_health_interval)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ticker.C:
+				b.performPoolHealthCheck()
+			case <-b.pool_stop:
+				b.Logger.Info(&libpack_logger.LogMessage{
+					Message: "Stopping connection pool health monitor",
+					Pairs:   nil,
+				})
+				return
+			}
+		}
+	}()
+}
+
+// performPoolHealthCheck executes health check queries to maintain pool connections
+// This keeps connections alive and detects/replaces dead connections
+func (b *BaseClient) performPoolHealthCheck() {
+	b.Logger.Debug(&libpack_logger.LogMessage{
+		Message: "Performing pool health check",
+		Pairs: map[string]interface{}{
+			"pool_size": b.pool_size,
+		},
+	})
+
+	startTime := time.Now()
+	var wg sync.WaitGroup
+	healthyCount := 0
+	unhealthyCount := 0
+	var mu sync.Mutex
+
+	// Check a subset of connections to ensure pool health
+	// We check pool_size/2 to balance between thoroughness and overhead
+	checkCount := max(1, b.pool_size/2)
+
+	for i := 0; i < checkCount; i++ {
+		wg.Add(1)
+		go func(index int) {
+			defer wg.Done()
+
+			// Create a context with timeout for health check
+			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+			defer cancel()
+
+			// Use a channel to handle timeout
+			done := make(chan error, 1)
+			go func() {
+				_, err := b.Query(b.pool_warmup_query, nil, nil)
+				done <- err
+			}()
+
+			select {
+			case err := <-done:
+				mu.Lock()
+				if err != nil {
+					unhealthyCount++
+					b.Logger.Warning(&libpack_logger.LogMessage{
+						Message: "Pool health check failed",
+						Pairs: map[string]interface{}{
+							"check_index": index,
+							"error":       err.Error(),
+						},
+					})
+				} else {
+					healthyCount++
+				}
+				mu.Unlock()
+			case <-ctx.Done():
+				mu.Lock()
+				unhealthyCount++
+				b.Logger.Warning(&libpack_logger.LogMessage{
+					Message: "Pool health check timeout",
+					Pairs: map[string]interface{}{
+						"check_index": index,
+					},
+				})
+				mu.Unlock()
+			}
+		}(i)
+	}
+
+	wg.Wait()
+	duration := time.Since(startTime)
+
+	b.Logger.Debug(&libpack_logger.LogMessage{
+		Message: "Pool health check completed",
+		Pairs: map[string]interface{}{
+			"healthy":     healthyCount,
+			"unhealthy":   unhealthyCount,
+			"checked":     checkCount,
+			"duration_ms": duration.Milliseconds(),
+		},
+	})
+
+	// If more than 50% of checks failed, trigger a pool refresh
+	if unhealthyCount > checkCount/2 {
+		b.Logger.Warning(&libpack_logger.LogMessage{
+			Message: "Pool health degraded, triggering refresh",
+			Pairs: map[string]interface{}{
+				"unhealthy_ratio": float64(unhealthyCount) / float64(checkCount),
+			},
+		})
+		b.refreshConnectionPool()
+	}
+}
+
+// refreshConnectionPool attempts to refresh the connection pool
+// by executing warmup queries to replace stale connections
+func (b *BaseClient) refreshConnectionPool() {
+	b.Logger.Info(&libpack_logger.LogMessage{
+		Message: "Refreshing connection pool",
+		Pairs: map[string]interface{}{
+			"pool_size": b.pool_size,
+		},
+	})
+
+	var wg sync.WaitGroup
+	refreshCount := max(1, b.pool_size/3) // Refresh 1/3 of pool
+
+	for i := 0; i < refreshCount; i++ {
+		wg.Add(1)
+		go func(index int) {
+			defer wg.Done()
+
+			_, err := b.Query(b.pool_warmup_query, nil, nil)
+			if err != nil {
+				b.Logger.Debug(&libpack_logger.LogMessage{
+					Message: "Pool refresh connection failed",
+					Pairs: map[string]interface{}{
+						"connection_index": index,
+						"error":            err.Error(),
+					},
+				})
+			} else {
+				b.Logger.Debug(&libpack_logger.LogMessage{
+					Message: "Pool connection refreshed",
+					Pairs: map[string]interface{}{
+						"connection_index": index,
+					},
+				})
+			}
+		}(i)
+	}
+
+	wg.Wait()
+}
+
+// StopPoolMonitor gracefully stops the pool health monitor
+// Call this when shutting down the application
+// Uses sync.Once to ensure it only executes once, preventing race conditions
+func (b *BaseClient) StopPoolMonitor() {
+	if b.pool_warmup_enabled {
+		b.pool_stop_once.Do(func() {
+			b.Logger.Info(&libpack_logger.LogMessage{
+				Message: "Stopping pool monitor",
+				Pairs:   nil,
+			})
+			b.pool_stop <- true
+		})
+	}
+}

pool_test.go

@@ -0,0 +1,135 @@
+package gql
+
+import (
+	"os"
+	"testing"
+	"time"
+)
+
+func (suite *Tests) TestPoolWarmup() {
+	suite.T().Run("should create client with pool warmup disabled by default", func(t *testing.T) {
+		// Save original env vars
+		originalPoolEnabled := os.Getenv("GRAPHQL_POOL_WARMUP_ENABLED")
+		originalEndpoint := os.Getenv("GRAPHQL_ENDPOINT")
+		defer func() {
+			os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", originalPoolEnabled)
+			os.Setenv("GRAPHQL_ENDPOINT", originalEndpoint)
+		}()
+
+		os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", "false")
+		os.Setenv("GRAPHQL_ENDPOINT", mockServer.URL)
+
+		client := NewConnection()
+		defer client.StopPoolMonitor()
+
+		assert.False(client.pool_warmup_enabled)
+		assert.Equal(5, client.pool_size) // Default size
+	})
+
+	suite.T().Run("should warmup pool when enabled", func(t *testing.T) {
+		originalPoolEnabled := os.Getenv("GRAPHQL_POOL_WARMUP_ENABLED")
+		originalPoolSize := os.Getenv("GRAPHQL_POOL_SIZE")
+		originalEndpoint := os.Getenv("GRAPHQL_ENDPOINT")
+		defer func() {
+			os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", originalPoolEnabled)
+			os.Setenv("GRAPHQL_POOL_SIZE", originalPoolSize)
+			os.Setenv("GRAPHQL_ENDPOINT", originalEndpoint)
+		}()
+
+		os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", "true")
+		os.Setenv("GRAPHQL_POOL_SIZE", "3")
+		os.Setenv("GRAPHQL_ENDPOINT", mockServer.URL)
+
+		startTime := time.Now()
+		client := NewConnection()
+		defer client.StopPoolMonitor()
+
+		duration := time.Since(startTime)
+
+		assert.True(client.pool_warmup_enabled)
+		assert.Equal(3, client.pool_size)
+		// Warmup should complete relatively quickly for 3 connections
+		assert.Less(duration.Seconds(), 5.0, "Pool warmup took too long")
+	})
+
+	suite.T().Run("should use custom warmup query", func(t *testing.T) {
+		originalPoolEnabled := os.Getenv("GRAPHQL_POOL_WARMUP_ENABLED")
+		originalQuery := os.Getenv("GRAPHQL_POOL_WARMUP_QUERY")
+		originalEndpoint := os.Getenv("GRAPHQL_ENDPOINT")
+		defer func() {
+			os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", originalPoolEnabled)
+			os.Setenv("GRAPHQL_POOL_WARMUP_QUERY", originalQuery)
+			os.Setenv("GRAPHQL_ENDPOINT", originalEndpoint)
+		}()
+
+		os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", "false") // Don't actually warmup, just test configuration
+		os.Setenv("GRAPHQL_POOL_WARMUP_QUERY", "query{__schema{queryType{name}}}")
+		os.Setenv("GRAPHQL_ENDPOINT", mockServer.URL)
+
+		client := NewConnection()
+		defer client.StopPoolMonitor()
+
+		assert.Equal("query{__schema{queryType{name}}}", client.pool_warmup_query)
+	})
+}
+
+func (suite *Tests) TestPoolHealthMonitor() {
+	suite.T().Run("should stop pool monitor gracefully", func(t *testing.T) {
+		client := CreateTestClient()
+		client.pool_warmup_enabled = false
+
+		// Should not panic
+		client.StopPoolMonitor()
+
+		assert.True(true, "Handled stop gracefully when monitor not running")
+	})
+
+	suite.T().Run("should handle multiple stop calls", func(t *testing.T) {
+		originalPoolEnabled := os.Getenv("GRAPHQL_POOL_WARMUP_ENABLED")
+		originalPoolSize := os.Getenv("GRAPHQL_POOL_SIZE")
+		originalEndpoint := os.Getenv("GRAPHQL_ENDPOINT")
+		defer func() {
+			os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", originalPoolEnabled)
+			os.Setenv("GRAPHQL_POOL_SIZE", originalPoolSize)
+			os.Setenv("GRAPHQL_ENDPOINT", originalEndpoint)
+		}()
+
+		os.Setenv("GRAPHQL_POOL_WARMUP_ENABLED", "true")
+		os.Setenv("GRAPHQL_POOL_SIZE", "2")
+		os.Setenv("GRAPHQL_ENDPOINT", mockServer.URL)
+
+		client := NewConnection()
+
+		// Call stop multiple times - should not panic
+		client.StopPoolMonitor()
+		client.StopPoolMonitor()
+		client.StopPoolMonitor()
+
+		assert.True(true, "Handled multiple stop calls gracefully")
+	})
+}
+
+func (suite *Tests) TestPoolHealthCheck() {
+	suite.T().Run("should perform health check without panic", func(t *testing.T) {
+		client := CreateTestClient()
+		client.pool_warmup_enabled = true
+		client.pool_size = 2
+		client.pool_warmup_query = "query{__typename}"
+
+		// Perform a health check - should not panic
+		client.performPoolHealthCheck()
+
+		assert.True(true, "Health check completed")
+	})
+
+	suite.T().Run("should refresh pool without panic", func(t *testing.T) {
+		client := CreateTestClient()
+		client.pool_size = 2
+		client.pool_warmup_query = "query{__typename}"
+
+		// Perform pool refresh - should not panic
+		client.refreshConnectionPool()
+
+		assert.True(true, "Pool refresh completed")
+	})
+}

query.go

@@ -10,13 +10,6 @@ import (
 	libpack_logger "github.com/lukaszraczylo/go-simple-graphql/logging"
 )
 
-// Size limit constants for security
-const (
-	MaxQuerySize    = 100 * 1024       // 100KB max query size
-	MaxVariableSize = 10 * 1024        // 10KB max variables size
-	MaxResponseSize = 10 * 1024 * 1024 // 10MB max response size
-)
-
 // minifyGraphQLQuery removes unnecessary whitespace from GraphQL queries while preserving string literals
 func minifyGraphQLQuery(query string) string {
 	if query == "" {
@@ -245,10 +238,7 @@ func (b *BaseClient) compileQuery(queryPartials ...any) *Query {
 
 	// Apply query minification if enabled (default: true)
 	finalQuery := query
-	b.mu.RLock()
-	minifyEnabled := b.minify_queries
-	b.mu.RUnlock()
-	if minifyEnabled {
+	if b.minify_queries {
 		originalSize := len(query)
 		minifiedQuery := minifyGraphQLQuery(query)
 		minifiedSize := len(minifiedQuery)
@@ -278,36 +268,9 @@ func (b *BaseClient) compileQuery(queryPartials ...any) *Query {
 }
 
 func (b *BaseClient) Query(query string, variables map[string]interface{}, headers map[string]interface{}) (any, error) {
-	// Validate query size limit
-	if len(query) > MaxQuerySize {
-		b.Logger.Error(&libpack_logger.LogMessage{
-			Message: "Query exceeds maximum size limit",
-			Pairs: map[string]interface{}{
-				"query_size": len(query),
-				"max_size":   MaxQuerySize,
-			},
-		})
-		return nil, fmt.Errorf("query size %d exceeds maximum allowed size of %d bytes", len(query), MaxQuerySize)
-	}
-
 	// Process flags before compilation to avoid recompilation
 	enableCache, enableRetries, cleanedVariables := processFlags(variables, headers)
 
-	// Validate variables size limit
-	if cleanedVariables != nil {
-		variablesJSON, err := json.Marshal(cleanedVariables)
-		if err == nil && len(variablesJSON) > MaxVariableSize {
-			b.Logger.Error(&libpack_logger.LogMessage{
-				Message: "Variables exceed maximum size limit",
-				Pairs: map[string]interface{}{
-					"variables_size": len(variablesJSON),
-					"max_size":       MaxVariableSize,
-				},
-			})
-			return nil, fmt.Errorf("variables size %d exceeds maximum allowed size of %d bytes", len(variablesJSON), MaxVariableSize)
-		}
-	}
-
 	// Compile query once with cleaned variables
 	compiledQuery := b.compileQuery(query, cleanedVariables)
 	if compiledQuery == nil || compiledQuery.JsonQuery == nil {
@@ -319,14 +282,11 @@ func (b *BaseClient) Query(query string, variables map[string]interface{}, heade
 	}
 	b.Logger.Debug(&libpack_logger.LogMessage{
 		Message: "Compiled query",
-		Pairs:   map[string]interface{}{"query": sanitizeForLogging(compiledQuery.Query)},
+		Pairs:   map[string]interface{}{"query": compiledQuery},
 	})
 
 	var queryHash string
-	b.mu.RLock()
-	cacheGlobal := b.cache_global
-	b.mu.RUnlock()
-	if (enableCache || cacheGlobal) && strutil.HasPrefix(compiledQuery.Query, "query") {
+	if (enableCache || b.cache_global) && strutil.HasPrefix(compiledQuery.Query, "query") {
 		b.Logger.Debug(&libpack_logger.LogMessage{
 			Message: "Cache enabled",
 			Pairs:   nil,
@@ -335,13 +295,13 @@ func (b *BaseClient) Query(query string, variables map[string]interface{}, heade
 		if cachedValue := b.cacheLookup(queryHash); cachedValue != nil {
 			b.Logger.Debug(&libpack_logger.LogMessage{
 				Message: "Cache hit",
-				Pairs:   map[string]interface{}{"query_hash": queryHash},
+				Pairs:   map[string]interface{}{"query": compiledQuery},
 			})
 			return b.decodeResponse(cachedValue)
 		}
 		b.Logger.Debug(&libpack_logger.LogMessage{
 			Message: "Cache miss",
-			Pairs:   map[string]interface{}{"query_hash": queryHash},
+			Pairs:   map[string]interface{}{"query": compiledQuery},
 		})
 	}
 
@@ -355,11 +315,7 @@ func (b *BaseClient) Query(query string, variables map[string]interface{}, heade
 			}
 			return "no-cache"
 		}(),
-		Retries: func() bool {
-			b.mu.RLock()
-			defer b.mu.RUnlock()
-			return enableRetries || b.retries_enable
-		}(),
+		Retries: enableRetries || b.retries_enable,
 	}
 
 	rv, err := q.executeQuery()

query_minification_test.go

@@ -8,7 +8,6 @@ import (
 )
 
 func TestMinifyGraphQLQuery(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 
 	tests := []struct {
@@ -132,7 +131,6 @@ func TestMinifyGraphQLQuery(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			t.Parallel()
 			result := minifyGraphQLQuery(tt.input)
 			assert.Equal(tt.expected, result, "Minified query should match expected output")
 
@@ -152,7 +150,6 @@ func TestMinifyGraphQLQuery(t *testing.T) {
 }
 
 func TestMinifyGraphQLQuerySizeReduction(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 
 	// Test with a heavily formatted query
@@ -211,11 +208,9 @@ func TestMinifyGraphQLQuerySizeReduction(t *testing.T) {
 }
 
 func TestBaseClientQueryMinification(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 
 	t.Run("should_minify_queries_by_default", func(t *testing.T) {
-		t.Parallel()
 		client := CreateTestClient()
 
 		// Verify minification is enabled by default
@@ -238,7 +233,6 @@ func TestBaseClientQueryMinification(t *testing.T) {
 	})
 
 	t.Run("should_respect_minification_disabled", func(t *testing.T) {
-		t.Parallel()
 		client := CreateTestClient()
 		client.SetQueryMinification(false)
 
@@ -260,7 +254,6 @@ func TestBaseClientQueryMinification(t *testing.T) {
 	})
 
 	t.Run("should_handle_string_literals_correctly", func(t *testing.T) {
-		t.Parallel()
 		client := CreateTestClient()
 
 		query := `mutation test($value: String!) {
@@ -285,7 +278,6 @@ func TestBaseClientQueryMinification(t *testing.T) {
 	})
 
 	t.Run("should_demonstrate_size_reduction_with_production_case", func(t *testing.T) {
-		t.Parallel()
 		client := CreateTestClient()
 
 		// Use the production case from trailing garbage test
@@ -332,7 +324,6 @@ func TestBaseClientQueryMinification(t *testing.T) {
 }
 
 func TestIsAlphaNumeric(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 
 	tests := []struct {
@@ -360,7 +351,6 @@ func TestIsAlphaNumeric(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(string(tt.char), func(t *testing.T) {
-			t.Parallel()
 			result := isAlphaNumeric(tt.char)
 			assert.Equal(tt.expected, result, "isAlphaNumeric should correctly identify character type")
 		})
@@ -368,11 +358,9 @@ func TestIsAlphaNumeric(t *testing.T) {
 }
 
 func TestQueryMinificationEnvironmentVariable(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 
 	t.Run("should_respect_GRAPHQL_MINIFY_QUERIES_env_var", func(t *testing.T) {
-		t.Parallel()
 		// This test would require setting environment variables
 		// For now, we'll test the default behavior
 		client := NewConnection()
@@ -383,23 +371,19 @@ func TestQueryMinificationEnvironmentVariable(t *testing.T) {
 }
 
 func TestQueryMinificationEdgeCases(t *testing.T) {
-	t.Parallel()
 	assert := assertions.New(t)
 
 	t.Run("should_handle_empty_query", func(t *testing.T) {
-		t.Parallel()
 		result := minifyGraphQLQuery("")
 		assert.Equal("", result, "Empty query should remain empty")
 	})
 
 	t.Run("should_handle_query_with_only_whitespace", func(t *testing.T) {
-		t.Parallel()
 		result := minifyGraphQLQuery("   \n\t  \n  ")
 		assert.Equal("", result, "Query with only whitespace should become empty")
 	})
 
 	t.Run("should_handle_nested_quotes", func(t *testing.T) {
-		t.Parallel()
 		query := `mutation test {
 			insert_test(value: "String with \"nested quotes\" and 'mixed' quotes") {
 				id
@@ -411,7 +395,6 @@ func TestQueryMinificationEdgeCases(t *testing.T) {
 	})
 
 	t.Run("should_preserve_spaces_between_keywords", func(t *testing.T) {
-		t.Parallel()
 		query := `query test($var: String!) {
 			field(where: {id: {_eq: $var}}) {
 				id

request_compression_test.go

@@ -11,6 +11,7 @@ import (
 
 	assertions "github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/suite"
+	"golang.org/x/net/http2"
 )
 
 type RequestCompressionTestSuite struct {
@@ -71,21 +72,26 @@ func (suite *RequestCompressionTestSuite) TestRequestCompression() {
 				client.endpoint = endpoint
 
 				// Create HTTP client using the same logic as the library
-				httpClient, err := client.createHttpClient()
-				assert.NoError(err, "HTTP client should be created without error")
+				httpClient := client.createHttpClient()
 				assert.NotNil(httpClient, "HTTP client should be created")
 
-				// Verify transport settings
+				// Verify transport settings based on protocol
 				if strings.HasPrefix(endpoint, "http://") {
-					// HTTP/1.1 transport
+					// HTTP/1.1 transport for http:// (h2c rarely supported)
 					transport, ok := httpClient.Transport.(*http.Transport)
-					assert.True(ok, "Should be http.Transport for HTTP endpoints")
+					assert.True(ok, "Should be http.Transport for http:// endpoints")
 					if ok {
-						assert.True(transport.DisableCompression, "DisableCompression should be true for HTTP transport")
+						assert.True(transport.DisableCompression, "DisableCompression should be true to prevent trailing garbage")
 					}
 				} else {
-					// HTTP/2 transport - this is where the issue might be
-					// We need to ensure HTTP/2 transport also has compression disabled
+					// HTTP/2 transport for https://
+					transport, ok := httpClient.Transport.(*http2.Transport)
+					assert.True(ok, "Should be http2.Transport for https:// endpoints")
+					if ok {
+						assert.True(transport.DisableCompression, "DisableCompression should be true to prevent trailing garbage")
+						assert.True(transport.AllowHTTP, "AllowHTTP should be true")
+						assert.NotNil(transport.TLSClientConfig, "TLSClientConfig should be set for https:// endpoints")
+					}
 				}
 
 				qe := &QueryExecutor{

sanitize.go

@@ -1,63 +0,0 @@
-package gql
-
-import (
-	"regexp"
-	"strings"
-)
-
-// Sensitive data patterns to redact from logs
-var (
-	// Pattern for common sensitive field names in JSON/GraphQL
-	sensitiveFieldPattern = regexp.MustCompile(`(?i)"?(password|passwd|pwd|token|apikey|api_key|api-key|secret|authorization|auth|bearer|credentials|private_key|private-key|access_token|refresh_token|client_secret|session|cookie)"?\s*:\s*"[^"]*"`)
-
-	// Pattern for authorization headers
-	authHeaderPattern = regexp.MustCompile(`(?i)(authorization|x-api-key|x-auth-token|bearer)\s*:\s*[^\s,}]+`)
-
-	// Pattern for basic auth in URLs
-	basicAuthURLPattern = regexp.MustCompile(`(https?://)([^:]+):([^@]+)@`)
-
-	// Pattern for JWT tokens
-	jwtPattern = regexp.MustCompile(`eyJ[A-Za-z0-9_-]+\.eyJ[A-Za-z0-9_-]+\.[A-Za-z0-9_-]+`)
-)
-
-const redactedText = "[REDACTED]"
-
-// sanitizeForLogging removes sensitive data from strings before logging
-// This includes passwords, tokens, API keys, authorization headers, etc.
-func sanitizeForLogging(input string) string {
-	if input == "" {
-		return input
-	}
-
-	// Create a working copy
-	sanitized := input
-
-	// Redact sensitive fields in JSON/GraphQL
-	sanitized = sensitiveFieldPattern.ReplaceAllStringFunc(sanitized, func(match string) string {
-		// Preserve the field name but redact the value
-		parts := strings.SplitN(match, ":", 2)
-		if len(parts) == 2 {
-			fieldName := parts[0]
-			return fieldName + `: "` + redactedText + `"`
-		}
-		return redactedText
-	})
-
-	// Redact authorization headers
-	sanitized = authHeaderPattern.ReplaceAllStringFunc(sanitized, func(match string) string {
-		parts := strings.SplitN(match, ":", 2)
-		if len(parts) == 2 {
-			headerName := parts[0]
-			return headerName + ": " + redactedText
-		}
-		return redactedText
-	})
-
-	// Redact basic auth in URLs
-	sanitized = basicAuthURLPattern.ReplaceAllString(sanitized, "${1}"+redactedText+":"+redactedText+"@")
-
-	// Redact JWT tokens
-	sanitized = jwtPattern.ReplaceAllString(sanitized, redactedText)
-
-	return sanitized
-}

structs.go

@@ -10,18 +10,24 @@ import (
 )
 
 type BaseClient struct {
-	mu             sync.RWMutex // Protects all fields for thread-safe access
-	cache          *cache.Cache
-	Logger         *logging.Logger
-	client         *http.Client
-	endpoint       string
-	responseType   string
-	retries_delay  time.Duration
-	retries_number int
-	MaxGoRoutines  int
-	cache_global   bool
-	retries_enable bool
-	minify_queries bool // Enable GraphQL query minification (default: true)
+	cache                *cache.Cache
+	Logger               *logging.Logger
+	client               *http.Client
+	endpoint             string
+	responseType         string
+	retries_delay        time.Duration
+	retries_number       int
+	retries_patterns     []string      // Error patterns that should trigger retries
+	pool_size            int           // Number of connections to pre-warm
+	pool_warmup_enabled  bool          // Enable connection pool warmup
+	pool_warmup_query    string        // Query to use for warming up connections
+	pool_health_interval time.Duration // Interval for pool health checks
+	pool_stop            chan bool     // Channel to stop pool monitor
+	pool_stop_once       sync.Once     // Ensures StopPoolMonitor is called only once
+	MaxGoRoutines        int
+	cache_global         bool
+	retries_enable       bool
+	minify_queries       bool // Enable GraphQL query minification (default: true)
 }
 
 type Query struct {

suite_test.go

@@ -2,7 +2,6 @@ package gql
 
 import (
 	"net/http/httptest"
-	"os"
 	"testing"
 
 	assertions "github.com/stretchr/testify/assert"
@@ -14,19 +13,11 @@ type Tests struct {
 }
 
 var (
-	assert                    *assertions.Assertions
-	mockServer                *httptest.Server
-	originalInsecureSkipValue string
+	assert     *assertions.Assertions
+	mockServer *httptest.Server
 )
 
 func (suite *Tests) SetupSuite() {
-	// Save original environment variable value
-	originalInsecureSkipValue = os.Getenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-
-	// Set environment variable to skip TLS verification for test mock server
-	// The mock server uses self-signed certificates
-	os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", "true")
-
 	// Start mock GraphQL server
 	mockServer = StartMockServer()
 }
@@ -39,13 +30,6 @@ func (suite *Tests) TearDownSuite() {
 
 	// Cleanup shared test cache
 	CleanupTestCache()
-
-	// Restore original environment variable value
-	if originalInsecureSkipValue != "" {
-		os.Setenv("GRAPHQL_INSECURE_SKIP_VERIFY", originalInsecureSkipValue)
-	} else {
-		os.Unsetenv("GRAPHQL_INSECURE_SKIP_VERIFY")
-	}
 }
 
 func (suite *Tests) SetupTest() {