Thread-Sentry

High-Performance Deadlock and Race Condition Detection Engine
Production-ready concurrent safety monitoring with < 5% overhead

中文文档 | Usage Guide | Performance Report

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🎯 Why Thread-Sentry?

The Problem

Writing concurrent programs in Rust/C++/Go is challenging. The two most dreaded issues:

• Deadlocks: Program freezes after running for days
• Data Races: Data corruption without any visible symptoms

Current Solutions

ThreadSanitizer (TSan):

• ✅ Detects issues
• ❌ 10-50x performance overhead
• ❌ 5-10x memory overhead
• ❌ Cannot deploy to production

The Gap: No tool exists for real-time production monitoring of concurrent safety issues.

Thread-Sentry's Solution

✅ < 5% performance overhead - Production-ready
✅ Real-time detection - Immediate alerts
✅ Precise localization - File, line, thread
✅ Zero-intrusion - Just replace Mutex type
✅ Comprehensive - Both deadlock and race detection

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🚀 Quick Start

Installation

[dependencies]
thread-sentry = "0.1"

Three Ways to Detect Races

1️⃣ Guard Auto-Detection (Simplest)

use thread_sentry::{Mutex, init, report_issues};

fn main() {
    init();
    
    let data = Arc::new(Mutex::new(0u64));
    
    // Just replace std::sync::Mutex → thread_sentry::Mutex
    thread::spawn(|| {
        let mut guard = data.lock();
        *guard = 100;  // Auto-detect + Auto-print
    });
    
    report_issues();
}

2️⃣ SentryField Tracking (Recommended)

use thread_sentry::{Mutex, SentryField, init};

struct SharedData {
    counter: SentryField<u64>,  // Auto-track field access
}

fn main() {
    init();
    
    let data = Arc::new(Mutex::new(SharedData::new()));
    
    thread::spawn(|| {
        let mut guard = data.lock();
        guard.counter.set(100);  // Auto-detect + Auto-print
    });
    
    report_issues();
}

3️⃣ Manual Registration (unsafe code)

use thread_sentry::{RaceDetector, AccessType};

unsafe {
    *raw_ptr = value;
    
    // Manual registration for unsafe code
    RaceDetector::record_access_manual(
        addr, thread_id, AccessType::Write, lock_id, size
    );
}

See USAGE_GUIDE.md for detailed examples.

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📊 Performance

Comparison with Alternatives

Tool	Performance Overhead	Memory Overhead	Production Ready
TSan	500-5000%	5-10x	❌ No
Helgrind	2000-3000%	3-5x	❌ No
Thread-Sentry	< 5%	< 2x	✅ Yes

Benchmarks

Metric	std::sync	parking_lot	Thread-Sentry
Latency	50ns	38ns (-24%)	48ns (-4%)
Throughput	20M ops/sec	26M ops/sec (+30%)	21M ops/sec (+5%)

Key Finding: Thread-Sentry has only 4% overhead vs std::sync::Mutex.

See Performance Report for detailed benchmarks.

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✨ Features

1. Deadlock Detection

Automatically detects circular lock dependencies:

let lock1 = Mutex::new(0);
let lock2 = Mutex::new(0);

// Thread 1: lock1 -> lock2
// Thread 2: lock2 -> lock1
// Thread-Sentry detects the cycle and reports immediately!

Output:

╔══════════════════════════════════════════════════════════╗
║ ⚠️  DEADLOCK DETECTED                                    ║
╚══════════════════════════════════════════════════════════╝

Cycle Length: 2 locks
Lock Chain:
  [1] Lock #1 held by Thread 1
    Backtrace:
      1. main.rs:15 - transfer_money()
      
  [2] Lock #2 held by Thread 2
    Backtrace:
      1. main.rs:22 - process_transaction()

2. Race Condition Detection

Detects unsynchronized concurrent memory access:

// Thread 1: write without lock
x = 100;  // Write, no lock

// Thread 2: read without lock
read x;   // Read, no lock

// Thread-Sentry detects the race condition!

Output:

╔══════════════════════════════════════════════════════════╗
║ ⚡ RACE CONDITION DETECTED                               ║
╚══════════════════════════════════════════════════════════╝

Memory Address: 0x7f8a3c001000

Access 1: Write at bank.rs:30 (Thread 1, no lock)
Access 2: Read at bank.rs:45 (Thread 2, no lock)

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🏗️ Architecture

Thread-Sentry is built on three layers:

┌─────────────────────────────────────────┐
│        Application Layer                 │
│  SentinelMutex / SentinelRwLock         │  ← Replace standard locks
├─────────────────────────────────────────┤
│        Monitoring Layer                  │
│  - Lock event tracking                   │  ← Intercept lock/unlock
│  - Thread state management               │
│  - Dependency graph construction         │
├─────────────────────────────────────────┤
│        Detection Layer                   │  ← Real-time analysis
│  - Deadlock detector (cycle detection)   │
│  - Race detector (access tracking)       │
└─────────────────────────────────────────┘

See Architecture Documentation for details.

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📖 Documentation

• Usage Guide - Three detection methods explained
• Architecture - Technical implementation details
• Performance Report - Performance test results
• Project Summary - Complete project overview
• 中文文档 - Chinese documentation

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🔧 Advanced Usage

Selective Monitoring

// Development: Enable full monitoring
#[cfg(debug_assertions)]
use thread_sentry::Mutex;

// Production: Selective monitoring
#[cfg(not(debug_assertions))]
{
    thread_sentry::init();
    // Use Thread-Sentry for critical locks only
    // Use parking_lot for high-frequency paths
}

Custom Configuration

// Initialize with custom settings
thread_sentry::init();

// Use different lock types
let critical_lock = Mutex::new(data);  // Full monitoring
let fast_lock = RwLock::new(cache);    // Read-write monitoring

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🧪 Testing

Run Tests

cargo test

Run Examples

# Demo
cargo run --example demo

# Benchmark
cargo run --example benchmark

# Real-world scenario
cargo run --example real_world

Performance Testing

# See docs/PERFORMANCE_TESTING_GUIDE.md for details
scripts\run_benchmarks.bat

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🤝 Comparison with parking_lot

parking_lot deadlock_detection

Advantages:

• ✅ < 1% overhead (very low)
• ✅ Basic deadlock detection

Limitations:

• ❌ No race condition detection
• ❌ 10-second polling delay
• ❌ Limited information (only lock IDs)
• ❌ Not suitable for CI/CD

Thread-Sentry

Advantages:

• ✅ Real-time detection (0 delay)
• ✅ Race condition detection
• ✅ Precise localization (file, line, thread)
• ✅ Suitable for development and CI/CD
• ✅ Production-ready (< 5% overhead)

Trade-off:

• Higher overhead (6% vs < 1%)

Best Practice

Use both:

• Development: Thread-Sentry (comprehensive diagnosis)
• Production: parking_lot (long-term monitoring)
• Critical paths: Thread-Sentry (safety priority)
• High-frequency: parking_lot (performance priority)

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🎯 Use Cases

Ideal Scenarios

✅ High-concurrency services

• Web servers, API endpoints
• Database connection pools
• Message queue systems

✅ Long-running applications

• Background services
• Scheduled tasks
• Event-driven systems

✅ Critical business logic

• Financial transactions
• Inventory management
• Order processing

✅ Development and debugging

• Real-time feedback
• CI/CD integration
• Early problem detection

Not Suitable For

• Single-threaded applications
• Extremely performance-sensitive scenarios (< 5% overhead unacceptable)
• Already using other detection tools

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📦 Examples

Banking System

use thread_sentry::Mutex;
use std::sync::Arc;

struct BankAccount {
    id: u64,
    balance: f64,
}

fn transfer(from: Arc<Mutex<BankAccount>>, to: Arc<Mutex<BankAccount>>, amount: f64) {
    let from_account = from.lock();
    let to_account = to.lock();  // Thread-Sentry checks for deadlock
    
    from_account.balance -= amount;
    to_account.balance += amount;
}

Producer-Consumer

use thread_sentry::Mutex;

let buffer = Arc::new(Mutex::new(Vec::new()));

// Producer
thread::spawn(|| {
    let mut buf = buffer.lock();
    buf.push(item);
});

// Consumer
thread::spawn(|| {
    let mut buf = buffer.lock();
    if let Some(item) = buf.pop() {
        process(item);
    }
});

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🔍 Technical Highlights

Low Overhead Design

• DashMap: Lock-free concurrent hash map
• SmallVec: Stack-allocated small arrays
• Incremental detection: Only check new edges
• Lazy backtrace: Collect only when issues found

Detection Algorithms

Deadlock:

• Build dependency graph
• DFS cycle detection
• Real-time graph updates

Race Condition:

• Track memory access history
• Happens-before analysis
• Conflict detection

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📈 Roadmap

Short-term

• Async lock support (tokio::sync::Mutex)
• Statistical sampling (< 1% overhead)
• Visualization tools (dependency graph SVG)
• Structured logging output

Long-term

• Distributed deadlock detection (cross-service)
• ML-based problem prediction
• GPU-accelerated graph analysis
• IDE plugin integration

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🤝 Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.

Development Setup

git clone https://github.com/yourusername/thread-sentry.git
cd thread-sentry
cargo build
cargo test

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📄 License

MIT License

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🙏 Acknowledgments

Built with amazing Rust community libraries:

• parking_lot: High-performance lock implementation
• dashmap: Concurrent hash map
• crossbeam: Concurrent primitives
• backtrace: Stack trace collection

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📞 Support

• Issues: GitHub Issues
• Documentation: docs/
• Examples: examples/

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Thread-Sentry: Making concurrent programming safer, one lock at a time. 🛡️