EFLOWCTRL grpc resource_error ai_generated partial

INTERNAL: grpc: flow control window exhausted for stream 123

ID: grpc/flow-control-window-exhausted

Also available as: JSON · Markdown · 中文
75%Fix Rate
82%Confidence
1Evidence
2024-01-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
gRPC v1.56.0 active — — —
gRPC v1.60.0 active — — —
gRPC v1.63.0 active — — —

Root Cause

The HTTP/2 flow control window for a specific stream is exhausted because the receiver is not consuming data fast enough, leading to a stall or internal error.

generic

中文

特定流的 HTTP/2 流量控制窗口已耗尽，因为接收方没有足够快地消耗数据，导致停滞或内部错误。

Official Documentation

https://grpc.io/docs/guides/flow-control/

Workarounds

  1. 85% success Increase the initial flow control window size on the server: `server = grpc.server(futures.ThreadPoolExecutor(max_workers=10), options=[('grpc.initial_reconnect_backoff_ms', 1000), ('grpc.http2.min_recv_flow_control_window', 8388608)])` 
    Increase the initial flow control window size on the server: `server = grpc.server(futures.ThreadPoolExecutor(max_workers=10), options=[('grpc.initial_reconnect_backoff_ms', 1000), ('grpc.http2.min_recv_flow_control_window', 8388608)])`
  2. 80% success Optimize the receiver's data consumption by batching reads or using async I/O to avoid blocking the event loop. 
    Optimize the receiver's data consumption by batching reads or using async I/O to avoid blocking the event loop.
  3. 75% success Implement backpressure at the application layer: have the client send smaller chunks or wait for acknowledgments before sending more data. 
    Implement backpressure at the application layer: have the client send smaller chunks or wait for acknowledgments before sending more data.

中文步骤

  1. Increase the initial flow control window size on the server: `server = grpc.server(futures.ThreadPoolExecutor(max_workers=10), options=[('grpc.initial_reconnect_backoff_ms', 1000), ('grpc.http2.min_recv_flow_control_window', 8388608)])`
  2. Optimize the receiver's data consumption by batching reads or using async I/O to avoid blocking the event loop.
  3. Implement backpressure at the application layer: have the client send smaller chunks or wait for acknowledgments before sending more data.

Dead Ends

Common approaches that don't work:

  1. Restarting the client or server without changing flow control settings. 80% fail

    The window exhaustion recurs under the same load pattern; restarting only provides temporary relief.

  2. Disabling flow control entirely by setting `grpc.http2.lookahead_bytes` to 0. 70% fail

    Flow control is a fundamental HTTP/2 mechanism; disabling it can cause memory exhaustion and connection instability.

  3. Increasing the number of worker threads on the receiver side. 50% fail

    While it may help consume data faster, the root cause is often slow application-level processing, not thread count.