Container resets/crashes when HTTP request reaches receive_response_headers.started in httpcore.http11 logs despite using timeouts and connection pooling

[Mahdi-Ba]

Description:
I am experiencing an issue where my container crashes or resets immediately after an HTTP POST request logs this debug message:

2025-08-06 10:07:03,466 - httpcore.connection - DEBUG - close.started

2025-08-06 10:07:03,467 - httpcore.connection - DEBUG - close.complete

2025-08-06 10:07:03,468 - httpcore.connection - DEBUG - connect_tcp.started host='us-central1-aiplatform.googleapis.com' port=443 local_address=None timeout=60.0 socket_options=None

2025-08-06 10:07:03,653 - httpcore.connection - DEBUG - connect_tcp.complete return_value=<httpcore._backends.sync.SyncStream object at 0x7bd514187b10>

2025-08-06 10:07:03,654 - httpcore.connection - DEBUG - start_tls.started ssl_context=<ssl.SSLContext object at 0x7bd514731be0> server_hostname='us-central1-aiplatform.googleapis.com' timeout=60.0

2025-08-06 10:07:03,840 - httpcore.connection - DEBUG - start_tls.complete return_value=<httpcore._backends.sync.SyncStream object at 0x7bd62bd80250>

2025-08-06 10:07:03,840 - httpcore.http11 - DEBUG - send_request_headers.started request=<Request [b'POST']>

2025-08-06 10:07:03,841 - httpcore.http11 - DEBUG - send_request_headers.complete

2025-08-06 10:07:03,841 - httpcore.http11 - DEBUG - send_request_body.started request=<Request [b'POST']>

2025-08-06 10:07:04,201 - httpcore.http11 - DEBUG - send_request_body.complete

2025-08-06 10:07:04,202 - httpcore.http11 - DEBUG - receive_response_headers.started request=<Request [b'POST']>

The request headers and body are sent successfully, but right when the client starts receiving the response headers, the container unexpectedly resets.

Additional Info:

• I have implemented timeouts and configured a safe connection pool with a high number of connections to handle load smoothly.

Environment:

• Containerized app running on Docker
• HTTP client using httpcore (likely via httpx)
• Timeouts and connection pool settings already applied
• LLM Async Streaming like this https://github.com/encode/httpcore/discussions/990

What I have tried:

• Configured client timeouts to avoid hanging connections.
• Increased connection pool size for high concurrency.
• Checked container logs, but no specific errors aside from the sudden reset.

Request for help:

• Has anyone experienced sudden container restarts at the point of receive_response_headers.started?
• Could networking or httpcore bugs be the culprits despite proper timeout and connection management?
• Recommendations for debugging this issue further or any known workarounds would be highly appreciated.

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