Enhance OKX WebSocket client with improved task management and error handling

- Implemented enhanced task synchronization to prevent race conditions during WebSocket operations.
- Introduced reconnection locking to avoid concurrent reconnection attempts.
- Improved error handling in message processing and reconnection logic, ensuring graceful shutdown and task management.
- Added unit tests to verify the stability and reliability of the WebSocket client under concurrent operations.

docs/exchanges/okx_collector.md

@@ -634,93 +634,56 @@ OKX requires specific ping/pong format:
 # Ping interval must be < 30 seconds to avoid disconnection
 ```
 
-## Error Handling and Troubleshooting
+## Error Handling & Resilience
 
-### Common Issues and Solutions
+The OKX collector includes comprehensive error handling and automatic recovery mechanisms:
 
-#### 1. Connection Failures
+### Connection Management
+- **Automatic Reconnection**: Handles network disconnections with exponential backoff
+- **Task Synchronization**: Prevents race conditions during reconnection using asyncio locks
+- **Graceful Shutdown**: Properly cancels background tasks and closes connections
+- **Connection State Tracking**: Monitors connection health and validity
+
+### Enhanced WebSocket Handling (v2.1+)
+- **Race Condition Prevention**: Uses synchronization locks to prevent multiple recv() calls
+- **Task Lifecycle Management**: Properly manages background task startup and shutdown
+- **Reconnection Locking**: Prevents concurrent reconnection attempts
+- **Subscription Persistence**: Automatically re-subscribes to channels after reconnection
 
 ```python
-# Check connection status
-status = collector.get_status()
-if not status['websocket_connected']:
-    print("WebSocket not connected")
-    
-    # Check WebSocket state
-    ws_state = status.get('websocket_state', 'unknown')
-    
-    if ws_state == 'error':
-        print("WebSocket in error state - will auto-restart")
-    elif ws_state == 'reconnecting':
-        print("WebSocket is reconnecting...")
-    
-    # Manual restart if needed
-    await collector.restart()
+# The collector handles these scenarios automatically:
+# - Network interruptions
+# - WebSocket connection drops  
+# - OKX server maintenance
+# - Rate limiting responses
+# - Malformed data packets
+
+# Enhanced error logging for diagnostics
+collector = OKXCollector('BTC-USDT', [DataType.TRADE])
+stats = collector.get_status()
+print(f"Connection state: {stats['connection_state']}")
+print(f"Reconnection attempts: {stats['reconnect_attempts']}")
+print(f"Error count: {stats['error_count']}")
 ```
 
-#### 2. Ping/Pong Issues
+### Common Error Patterns
 
-```python
-# Monitor ping/pong status
-if 'websocket_stats' in status:
-    ws_stats = status['websocket_stats']
-    pings_sent = ws_stats.get('pings_sent', 0)
-    pongs_received = ws_stats.get('pongs_received', 0)
-    
-    if pings_sent > pongs_received + 3:  # Allow some tolerance
-        print("Ping/pong issue detected - connection may be stale")
-        # Auto-restart will handle this
+#### WebSocket Concurrency Errors (Fixed in v2.1)
 ```
-
-#### 3. Data Validation Errors
-
-```python
-# Monitor for validation errors
-errors = status.get('errors', 0)
-if errors > 0:
-    print(f"Data validation errors detected: {errors}")
-    
-    # Check logs for details:
-    # - Malformed messages
-    # - Missing required fields
-    # - Invalid data types
+ERROR: cannot call recv while another coroutine is already running recv or recv_streaming
 ```
+**Solution**: Updated WebSocket client with proper task synchronization and reconnection locking.
 
-#### 4. Performance Issues
-
+#### Connection Recovery
 ```python
-# Monitor message processing rate
-messages = status.get('messages_processed', 0)
-uptime = status.get('uptime_seconds', 1)
-rate = messages / uptime
-
-if rate < 1.0:  # Less than 1 message per second
-    print("Low message rate - check:")
-    print("- Network connectivity")
-    print("- OKX API status")
-    print("- Symbol activity")
-```
-
-### Debug Mode
-
-Enable debug logging for detailed information:
-
-```python
-import os
-os.environ['LOG_LEVEL'] = 'DEBUG'
-
-# Create collector with verbose logging
-collector = create_okx_collector(
-    symbol='BTC-USDT',
-    data_types=[DataType.TRADE, DataType.ORDERBOOK]
-)
-
-await collector.start()
-
-# Check logs in ./logs/ directory:
-# - okx_collector_btc_usdt_debug.log
-# - okx_collector_btc_usdt_info.log
-# - okx_collector_btc_usdt_error.log
+# Monitor connection health
+async def monitor_connection():
+    while True:
+        if collector.is_connected():
+            print("✅ Connected and receiving data")
+        else:
+            print("❌ Connection issue - auto-recovery in progress")
+        await asyncio.sleep(30)
 ```
 
 ## Testing