Add pool management.

README.md

@@ -43,6 +43,10 @@ Therefore, I present you the simple client to which you can copy & paste your gr
 * `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
 
@@ -85,6 +89,63 @@ 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: