feat: enhance squid config

[fatelei]

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Summary

fix #29642

Performance Optimization Configuration

1. Connection Limits

• max_filedescriptors 65536 - Support more concurrent connections
• maximum_tcp_connections 1000 - Maximum TCP connections

2. Timeout Configuration (optimized for image requests)

• connect_timeout 2 minutes - Connection timeout
• request_timeout 10 minutes - Request timeout (sufficient for large image downloads)
• read_timeout 10 minutes - Read timeout
• client_lifetime 24 hours - Client connection keep-alive time

3. Connection Reuse (improve performance)

• server_persistent_connections on - Server-side persistent connections
• client_persistent_connections on - Client-side persistent connections
• persistent_request_after_timeout 30 seconds - Reuse connections after timeout

4. Request Protection

• quick_abort_min/max/pct - Prevent near-completion requests from being interrupted
• client_idle_pconn_timeout - Idle connection timeout

5. Memory Cache

• cache_mem 256 MB - Memory cache size
• maximum_object_size_in_memory 512 KB - Suitable for small icons/avatars

6. DNS Optimization

• dns_nameservers 8.8.8.8 8.8.4.4 - Use public DNS servers
• dns_timeout 30 seconds - DNS timeout

These configurations should significantly improve timeout issues when handling high-concurrency image requests. You need to restart the squid service for the changes to take effect.

Screenshots

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Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

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[Copilot]

Pull request overview

This PR enhances the Squid proxy configuration to address timeout issues with high-concurrency image requests by adding comprehensive performance optimization settings including connection management, timeout configurations, persistent connections, and caching improvements.

Key Changes:

• Added extensive timeout configurations (connect, request, read) optimized for image handling
• Enabled persistent connections for both server and client sides with connection pooling
• Configured memory caching with 256 MB allocation and DNS optimization with public resolvers

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[baiyongrui]

This would make HTTP_REQUEST_MAX_WRITE_TIMEOUT invalid, as it's default value is 600s in /docker/.env

[baiyongrui]

workflow HTTP node would get "504 Bad Gateway" status code when response time exceed 2 minutes