LOGGING_FIX_SUMMARY.md

STT Service Logging Conflict Fix

Problem

The STT service at https://huggingface.co/spaces/pgits/stt-gpu-service was experiencing logging conflicts when starting up:

ValueError: I/O operation on closed file
ValueError: Unable to configure formatter 'default'

This occurred due to stdout/stderr conflicts between:

• ZeroGPU environment logging
• uvicorn server logging
• Gradio interface logging
• MCP server stdio protocol

Solution Implemented

1. ZeroGPU-Compatible Logging Setup

• Custom formatter: [STT-{level}] {message} format to avoid conflicts
• Safe stream handling: Uses sys.__stdout__ instead of potentially closed streams
• Handler cleanup: Removes existing handlers before adding new ones
• Library silencing: Reduces verbosity from transformers, torch, gradio, uvicorn

2. Fallback Safety Mechanism

• Safe logging function: safe_log() that falls back to print statements
• Error handling: Graceful degradation if logging configuration fails
• Dual protocol support: Maintains both Gradio and MCP functionality

3. MCP Server Error Handling

• Thread isolation: MCP server runs in separate thread with own event loop
• Graceful failures: Service continues if MCP server fails to start
• Stream protection: MCP stdio protocol doesn't interfere with Gradio

4. Enhanced Startup Process

• Warning suppression: Filters out UserWarning and FutureWarning
• Configuration staging: Logging setup happens before other imports
• Error recovery: Gradio continues even if MCP fails

Code Changes Made

Key Functions Added:

1. setup_zerogpu_logging() - ZeroGPU-compatible logging configuration
2. safe_log() - Robust logging with print fallback
3. Enhanced start_mcp_server_thread() - Better error handling
4. Improved run_mcp_server() - Exception handling for stdio conflicts

Environment Variables:

• GRADIO_SERVER_NAME=0.0.0.0
• GRADIO_SERVER_PORT=7860

Launch Parameters:

• quiet=True - Reduces Gradio logging noise
• enable_queue=True - Better request handling
• max_threads=4 - ZeroGPU thread limit

Testing

• ✅ Logging setup logic verified
• ✅ Safe logging fallback tested
• ✅ Stream isolation confirmed
• ✅ Dual server mode compatibility

Expected Results

1. Clean startup - No more "I/O operation on closed file" errors
2. Dual protocol support - Both Gradio UI and MCP API available
3. Graceful degradation - Service continues if one component fails
4. ZeroGPU compatibility - Optimized for HuggingFace Pro environment

Deployment

The fixed service should now start cleanly in the ZeroGPU environment with both:

• Gradio Interface: Available on port 7860 for web UI
• MCP Server: Available on stdio protocol for API integration

Monitoring

Check logs for these success indicators:

• [STT-INFO] 🚀 Starting STT service with dual protocol support...
• [STT-INFO] ✅ MCP Server: Available on stdio protocol
• [STT-INFO] ✅ Gradio Interface: Starting on port 7860...