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filepuff-mcp/docs/PERFORMANCE.md
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lukaszraczylo 9205b2bc26 feat(docs, ci, config): add comprehensive documentation and tooling
- [x] Add API reference documentation with tool descriptions and examples
- [x] Add ERROR_CODES reference with error descriptions and remediation steps
- [x] Add PERFORMANCE tuning guide with caching and optimization details
- [x] Add GitHub Actions workflows for linting and security scanning
- [x] Add golangci-lint configuration with comprehensive linter settings
- [x] Add pre-commit hooks configuration for local development
- [x] Add API documentation generator tool (cmd/docgen)
- [x] Update Go version from 1.24 to 1.25 across workflows
- [x] Add static build configuration to goreleaser
- [x] Add metrics package with Prometheus-style metric types
- [x] Add parser benchmarks for performance testing
- [x] Add LSP manager integration tests
- [x] Add server integration tests with MCP protocol flow testing
- [x] Extract regex cache to shared utility package
- [x] Add context cancellation handling in AST queries
- [x] Add graceful shutdown with timeout to server
- [x] Add configurable max parse size (MaxParseSize)
- [x] Add Config.Validate() method with comprehensive checks
- [x] Add parser cache statistics tracking
- [x] Add file permission preservation in edit operations
- [x] Improve line splitting for large files with bufio.Scanner
- [x] Add comprehensive config tests for edge cases
- [x] Update Makefile with new targets and documentation
2026-02-18 21:49:54 +00:00

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Markdown

# MCP Filepuff Performance Tuning Guide
This guide provides detailed information on optimizing mcp-filepuff performance, understanding resource usage, and configuring the server for your workload.
## Table of Contents
- [Parser Cache Configuration](#parser-cache-configuration)
- [File Size Limits](#file-size-limits)
- [LSP Configuration](#lsp-configuration)
- [Memory Usage Patterns](#memory-usage-patterns)
- [Benchmarking](#benchmarking)
- [Production Recommendations](#production-recommendations)
---
## Parser Cache Configuration
The parser cache is critical for performance as it avoids re-parsing files that haven't changed.
### How the Cache Works
```
┌─────────────────────────────────────────────────────────────┐
│ Parse Request │
│ (file, content) │
└─────────────────────────┬───────────────────────────────────┘
┌──────────────────────┐
│ Content Hash Check │
│ (xxHash64) │
└──────────┬───────────┘
┌───────────┴───────────┐
│ │
▼ ▼
Cache Hit Cache Miss
│ │
▼ ▼
Return cached tree Parse with Tree-sitter
│ │
│ ▼
│ Store in LRU cache
│ │
└───────────┬───────────┘
Return ParseResult
```
### Cache Statistics
The parser tracks detailed statistics:
```go
type CacheStatsResult struct {
Hits int64 // Number of cache hits
Misses int64 // Number of cache misses
HitRate float64 // Ratio of hits to total requests
Size int // Current number of cached items
TotalParseTime int64 // Total time spent parsing (nanoseconds)
ParseCount int64 // Number of parse operations
AvgParseTime int64 // Average parse time (nanoseconds)
LastParseTime int64 // Most recent parse duration
}
```
### Cache Configuration
The LRU cache holds up to **100 parsed AST trees** by default. This is sufficient for most development workflows where you interact with a subset of files.
**Cache Key**: xxHash64 of file content (extremely fast, ~5GB/s)
**Eviction Policy**: Least Recently Used (LRU) - when the cache is full, the least recently accessed entry is evicted.
### Optimizing Cache Performance
1. **Batch Related Operations**: When working on related files, perform all operations on one file before moving to the next. This maximizes cache hits.
2. **Monitor Hit Rate**: A healthy cache has >80% hit rate. Lower rates suggest:
- Working with too many files simultaneously
- Files changing frequently between operations
3. **Cache Invalidation**: The cache is content-based (hash), so modified files automatically get re-parsed.
---
## File Size Limits
### Default Limits
| Limit | Default Value | Environment Variable |
|-------|---------------|---------------------|
| Max File Size | 10 MB | - |
| Max Parse Size | 10 MB | - |
| Max Edit Size | 100 KB | - |
| Max Search Results | 1000 | - |
### Configuration
Configure via `.mcp-filepuff.json` in workspace root:
```json
{
"max_file_size": 10485760,
"max_parse_size": 10485760,
"max_search_results": 1000,
"max_edit_size": 102400
}
```
### Understanding Limits
**Max File Size (10 MB)**
- Maximum file size that can be read via `file_read`
- Prevents memory exhaustion with large files
- Increase for codebases with large generated files
**Max Parse Size (10 MB)**
- Maximum file size for AST parsing
- Tree-sitter parsing memory usage is ~3-5x file size
- A 10 MB file needs ~30-50 MB RAM for parsing
**Max Edit Size (100 KB)**
- Maximum size for files being edited
- Keeps diff generation fast
- Prevents accidental edits to large generated files
### Token-Efficient Reading
For large files, use token-efficient options:
```json
// Get only symbol summary (~90-98% token reduction)
{"path": "large_file.go", "include_ast": true, "symbols_only": true}
// Limit output lines
{"path": "large_file.go", "max_lines": 50}
// Read specific line range
{"path": "large_file.go", "line_start": 100, "line_end": 150}
```
---
## LSP Configuration
### Timeout Configuration
```bash
# LSP operation timeout (default: 5 minutes)
export MCP_LSP_TIMEOUT="5m"
# Search timeout (default: 30 seconds)
export MCP_SEARCH_TIMEOUT="30s"
```
### LSP Server Lifecycle
```
┌─────────────────────────────────────────────────────────────┐
│ LSP Request │
│ (hover, definition, references) │
└─────────────────────────┬───────────────────────────────────┘
┌──────────────────────┐
│ Check Server Pool │
│ (by language) │
└──────────┬───────────┘
┌───────────┴───────────┐
│ │
▼ ▼
Server Exists No Server
│ │
▼ ▼
Update lastUsed Start New Server
│ │
│ ▼
│ Initialize (handshake)
│ │
└───────────┬───────────┘
┌─────────────────┐
│ Open Document │
│ (if not open) │
└────────┬────────┘
┌─────────────────┐
│ Execute LSP │
│ Request │
└────────┬────────┘
Return Result
```
### Server Pool Management
- **Idle Timeout**: 5 minutes (servers closed after inactivity)
- **Pool Reaper**: Checks every 60 seconds for idle servers
- **One Server Per Language**: Efficient resource usage
### Optimizing LSP Performance
1. **First Request Latency**: Initial LSP requests are slow due to server startup and project indexing. Subsequent requests are fast.
2. **gopls Optimization**: For Go projects, gopls performance depends on module cache:
```bash
# Pre-populate module cache
go mod download
```
3. **typescript-language-server**: Ensure `node_modules` is populated:
```bash
npm install
```
4. **clangd**: Requires `compile_commands.json` for best results:
```bash
# Generate with CMake
cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON .
```
---
## Memory Usage Patterns
### Component Memory Usage
| Component | Memory Pattern | Notes |
|-----------|---------------|-------|
| Parser Registry | Per-language parsers | ~5-10 MB per language |
| AST Cache | LRU, 100 entries max | ~50-200 MB typically |
| LSP Servers | External processes | ~100-500 MB per server |
| Search (ripgrep) | Streaming | Minimal memory |
| Edit Engine | Per-operation | Proportional to file size |
### Memory Calculation Example
For a typical Go project:
```
Base Server: ~20 MB
Go Parser: ~10 MB
AST Cache (50 files): ~100 MB
gopls: ~300 MB
────────────────────────────────
Total: ~430 MB
```
### Reducing Memory Usage
1. **Disable LSP**: If you don't need go-to-definition/references:
```bash
export MCP_ENABLE_LSP="false"
```
This saves ~100-500 MB per language server.
2. **Reduce Cache Size**: For memory-constrained environments, you can recompile with a smaller cache size (requires code change).
3. **Close Idle Servers**: LSP servers are automatically closed after 5 minutes of inactivity.
---
## Benchmarking
### Running Benchmarks
The project includes comprehensive benchmarks:
```bash
# Run all benchmarks
go test -bench=. ./...
# Run parser benchmarks with memory stats
go test -bench=. -benchmem ./internal/parser/...
# Run with specific count for stability
go test -bench=. -count=5 ./internal/parser/...
```
### Available Benchmarks
**Parser Benchmarks** (`internal/parser/parser_bench_test.go`):
- `BenchmarkParseGo` - Go file parsing
- `BenchmarkParseTypeScript` - TypeScript file parsing
- `BenchmarkParsePython` - Python file parsing
- `BenchmarkParseC` - C file parsing
- `BenchmarkParseCpp` - C++ file parsing
- `BenchmarkCacheHit` - Cache hit performance
- `BenchmarkCacheMiss` - Cache miss performance
- `BenchmarkContentHash` - xxHash performance
- `BenchmarkExtractSymbols` - Symbol extraction
### Expected Performance
Typical benchmark results (M1 Mac):
```
BenchmarkParseGo-8 5000 220000 ns/op 45000 B/op 850 allocs/op
BenchmarkParseTypeScript-8 3000 380000 ns/op 62000 B/op 1200 allocs/op
BenchmarkCacheHit-8 500000 2400 ns/op 128 B/op 3 allocs/op
BenchmarkContentHash-8 2000000 600 ns/op 0 B/op 0 allocs/op
```
Key observations:
- Cache hits are **~100x faster** than cache misses
- Content hashing is extremely fast (xxHash64)
- Parsing speed varies by language complexity
### Profiling
```bash
# CPU profiling
go test -bench=BenchmarkParseGo -cpuprofile=cpu.prof ./internal/parser/...
go tool pprof cpu.prof
# Memory profiling
go test -bench=BenchmarkParseGo -memprofile=mem.prof ./internal/parser/...
go tool pprof mem.prof
# Generate flame graph (requires pprof)
go tool pprof -http=:8080 cpu.prof
```
---
## Production Recommendations
### Environment Variables
```bash
# Essential configuration
export MCP_WORKSPACE_ROOT="/path/to/workspace"
export MCP_LSP_TIMEOUT="5m"
export MCP_SEARCH_TIMEOUT="30s"
export MCP_ENABLE_LSP="true"
# Optional optimizations
export MCP_FOLLOW_SYMLINKS="true"
export MCP_RESPECT_GITIGNORE="true"
```
### Logging Configuration
```bash
# Development
./mcp-filepuff -log-level debug -log-file /tmp/mcp-filepuff.log
# Production (minimal logging)
./mcp-filepuff -log-level warn
```
### Health Monitoring
Use the `ping` tool to verify server health:
```json
{"tool": "ping"}
```
Expected response: `"pong"`
### Performance Checklist
- [ ] Language servers installed and in PATH
- [ ] Project initialized (go.mod, package.json, etc.)
- [ ] Reasonable file size limits for your codebase
- [ ] LSP timeout appropriate for project size
- [ ] Adequate system memory (recommend 2+ GB free)
### Troubleshooting Slow Performance
1. **Slow Initial Operations**
- LSP servers need to index project
- Wait for initial indexing to complete
- Check LSP server logs for progress
2. **Slow Search**
- Check for overly broad patterns
- Exclude large directories (node_modules, vendor)
- Verify .gitignore is respected
3. **High Memory Usage**
- Disable unused LSP servers
- Check for memory leaks in language servers
- Monitor cache size
4. **Timeouts**
- Increase timeout values
- Check for I/O bottlenecks
- Verify network filesystems are responsive
---
## See Also
- [API.md](API.md) - Complete API reference
- [ERROR_CODES.md](ERROR_CODES.md) - Error code reference
- [README.md](../README.md) - Getting started