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Connection Issues

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Redis Connection Failed

Symptoms: Cannot connect to Redis Solutions: 
# Verify Redis is running
redis-cli ping

# Check connection URL
echo $REDIS_URL

# Test connection
redis-cli -u $REDIS_URL ping

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Client Not Connecting

Symptoms: Client stuck in connecting state Solutions:
  • Verify API route path matches client URL
  • Check CORS configuration
  • Verify Redis is accessible
  • Check browser console for errors

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Message Issues

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Messages Not Received

Symptoms: emit() called but no event triggered Solutions:
  • Verify event names match exactly (case-sensitive)
  • Check both client and server are listening
  • Confirm client is connected (socket.connected)

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Acknowledgment Timeout

Symptoms: Ack callbacks timeout after 5 seconds Solutions:
  • Ensure server calls ack callback
  • Check for server-side errors
  • Verify Redis connectivity

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Performance Issues

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High Latency

Symptoms: Slow message delivery Solutions:
  • Check Redis latency: redis-cli --latency
  • Verify network connectivity
  • Consider switching from polling to SSE
  • Check Redis memory usage

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Memory Leaks

Symptoms: Increasing memory usage Solutions:
  • Ensure proper cleanup on disconnect
  • Set TTL for Redis keys
  • Monitor active connections
  • Check for event listener leaks

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Redis Issues

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Memory Full

Symptoms: Redis out of memory Solutions: 
# Check memory
redis-cli INFO memory

# Set eviction policy
redis-cli CONFIG SET maxmemory-policy allkeys-lru

# Set memory limit
redis-cli CONFIG SET maxmemory 256mb

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Connection Pool Exhausted

Symptoms: “Connection pool exhausted” errors Solutions: 
redisOptions: {
  maxRetriesPerRequest: 3,
  enableOfflineQueue: false,
  lazyConnect: true
}

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Debugging

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Enable Logging

server.on('connection', (socket) => {
  console.log('[DEBUG] Connection:', socket.id);
  
  socket.on('*', (event, data) => {
    console.log('[DEBUG] Event:', event, data);
  });
});

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Monitor Redis

# Watch all Redis commands
redis-cli MONITOR

# Check active keys
redis-cli KEYS "session:*"

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Next Steps