Skip to content
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension


Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
20 changes: 20 additions & 0 deletions .env.example
Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
# e6data Python Connector Environment Variables
# Copy this file to .env and fill in your actual values

# Required - e6data connection credentials
E6DATA_USERNAME=your-email@domain.com
E6DATA_PASSWORD=your-access-token-from-e6data-console

# Optional - connection settings (defaults provided)
E6DATA_HOST=localhost
E6DATA_PORT=443
E6DATA_DATABASE=test_db
E6DATA_CATALOG=default
E6DATA_CLUSTER_NAME=test_cluster
E6DATA_SECURE=true

# Usage:
# 1. Copy this file: cp .env.example .env
# 2. Edit .env with your actual credentials
# 3. Export variables: export $(grep -v '^#' .env | xargs)
# 4. Run tests: python test/test_simple_connection_pool.py
225 changes: 225 additions & 0 deletions CONNECTION_POOL_IMPLEMENTATION.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,225 @@
# Connection Pool Implementation for e6data Python Connector

## Overview

I've successfully implemented a robust, thread-safe connection pooling solution for the e6data Python connector. This implementation allows multiple threads to efficiently share and reuse connections, significantly reducing connection overhead and improving performance for concurrent query execution.

## Features Implemented

### 1. Thread-Safe Connection Management
- **Thread-local connection mapping**: Each thread can reuse its own connection across multiple queries
- **Synchronized access**: All pool operations protected by threading locks
- **Automatic connection assignment**: Threads automatically get assigned connections from the pool

### 2. Connection Lifecycle Management
- **Min/Max pool sizes**: Configurable minimum and maximum connection limits
- **Overflow connections**: Support for temporary overflow connections when pool is exhausted
- **Connection recycling**: Automatic recycling of connections based on age
- **Health checking**: Pre-ping and health verification before returning connections

### 3. Resource Management
- **Automatic cleanup**: Connections returned to pool after use
- **Context manager support**: Using `with` statement for automatic connection management
- **Graceful shutdown**: Proper cleanup of all connections when pool is closed

### 4. Monitoring and Statistics
- **Real-time statistics**: Track active, idle, and total connections
- **Request tracking**: Monitor total requests and failed connections
- **Thread monitoring**: Track waiting threads and thread-specific connections

## Implementation Files

### 1. `e6data_python_connector/connection_pool.py`
Main implementation containing:
- `ConnectionPool` class: Thread-safe pool manager
- `PooledConnection` class: Wrapper for pooled connections with metadata
- Health checking and connection replacement logic
- Statistics tracking and monitoring

### 2. `test_connection_pool.py`
Comprehensive test suite covering:
- Pool initialization and basic operations
- Thread-safe concurrent access
- Connection reuse within threads
- Health checking and recycling
- Overflow connection handling
- Context manager functionality

### 3. `demo_connection_pool.py`
Interactive demonstration showing:
- Basic pool usage patterns
- Concurrent query execution
- Connection reuse across queries
- Context manager usage
- Pool exhaustion handling

## Usage Examples

### Basic Usage
```python
from e6data_python_connector import ConnectionPool

# Create a connection pool
pool = ConnectionPool(
min_size=2,
max_size=10,
host='your.cluster.e6data.com',
port=443,
username='user@example.com',
password='access_token',
database='default',
cluster_name='your_cluster',
secure=True
)

# Get connection and execute query
conn = pool.get_connection()
cursor = conn.cursor()
cursor.execute("SELECT * FROM table")
results = cursor.fetchall()

# Return connection to pool
pool.return_connection(conn)
```

### Context Manager Pattern
```python
# Automatic connection management
with pool.get_connection_context() as conn:
cursor = conn.cursor()
cursor.execute("SELECT * FROM table")
results = cursor.fetchall()
# Connection automatically returned to pool
```

### Concurrent Query Execution
```python
import concurrent.futures

def execute_query(query_id, query):
# Each thread reuses its connection
conn = pool.get_connection()
cursor = conn.cursor()
cursor.execute(query)
results = cursor.fetchall()
pool.return_connection(conn)
return results

# Execute multiple queries concurrently
with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
queries = ["SELECT 1", "SELECT 2", "SELECT 3"]
futures = [executor.submit(execute_query, i, q) for i, q in enumerate(queries)]
results = [f.result() for f in concurrent.futures.as_completed(futures)]
```

## Key Design Decisions

### 1. Thread-Local Connection Reuse
- Same thread automatically reuses its assigned connection
- Reduces connection churn and improves performance
- Maintains connection state across queries

### 2. Health Checking Strategy
- Optional pre-ping before returning connections
- Automatic replacement of unhealthy connections
- Configurable connection recycling based on age

### 3. Overflow Management
- Temporary connections created when pool exhausted
- Automatically closed when returned if pool is full
- Prevents deadlocks while maintaining resource limits

### 4. Statistics and Monitoring
- Real-time pool statistics for debugging and monitoring
- Track connection usage patterns
- Identify performance bottlenecks

## Configuration Options

| Parameter | Default | Description |
|-----------|---------|-------------|
| `min_size` | 2 | Minimum connections to maintain |
| `max_size` | 10 | Maximum connections in pool |
| `max_overflow` | 5 | Additional temporary connections |
| `timeout` | 30.0 | Timeout for getting connection (seconds) |
| `recycle` | 3600 | Maximum connection age (seconds) |
| `debug` | False | Enable debug logging |
| `pre_ping` | True | Check connection health before use |

## Performance Benefits

### Without Connection Pool
- New connection created for each query
- Connection overhead for each operation
- No connection reuse between queries
- Higher latency and resource usage

### With Connection Pool
- Connections reused across queries
- Reduced connection overhead
- Better resource utilization
- Lower latency for query execution
- Thread-safe concurrent access

## Testing

Run the comprehensive test suite:
```bash
python -m unittest test_connection_pool.py -v
```

Run the interactive demo:
```bash
# Set environment variables
export ENGINE_IP=your.cluster.e6data.com
export EMAIL=user@example.com
export PASSWORD=access_token
export DB_NAME=default

# Run demo
python demo_connection_pool.py
```

## Integration with Existing Code

The connection pool is fully backward compatible. Existing code using direct `Connection` objects continues to work unchanged. To use pooling:

```python
# Instead of:
conn = Connection(host='...', port=443, ...)

# Use:
pool = ConnectionPool(host='...', port=443, ...)
conn = pool.get_connection()
# ... use connection ...
pool.return_connection(conn)
```

## Thread Safety Guarantees

1. **Pool operations**: All pool methods are thread-safe
2. **Connection reuse**: Same thread always gets same connection
3. **Statistics**: Safe to read from any thread
4. **Cleanup**: Safe to call from any thread

## Future Enhancements

Potential improvements for future versions:
1. **Async support**: Add async/await support for async applications
2. **Connection warming**: Pre-execute queries to warm connections
3. **Load balancing**: Distribute connections across multiple clusters
4. **Metrics integration**: Export metrics to monitoring systems
5. **Connection pooling strategies**: Different allocation strategies (LIFO, FIFO, LRU)

## Summary

The connection pool implementation provides:
- ✅ Thread-safe connection sharing and reuse
- ✅ Automatic connection lifecycle management
- ✅ Health checking and connection recovery
- ✅ Overflow connection support
- ✅ Comprehensive monitoring and statistics
- ✅ Context manager support
- ✅ Full backward compatibility

This implementation significantly improves performance for applications executing multiple concurrent queries by eliminating connection overhead and enabling efficient connection reuse across threads.
Loading