file: use buffered pipes to prevent deadlock during pack negotiation#1826
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lukemarsden wants to merge 1 commit intogo-git:mainfrom
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file: use buffered pipes to prevent deadlock during pack negotiation#1826lukemarsden wants to merge 1 commit intogo-git:mainfrom
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The file transport uses in-process pipes to communicate between client and server. With unbuffered io.Pipe, both sides can deadlock when cloning repositories with many refs (e.g., 300+ branches). The deadlock occurs because: 1. Client writes "have" lines to stdin pipe 2. Server writes advertised refs and ACKs to stdout pipe 3. Both pipes fill up (io.Pipe has zero buffer) 4. Both sides block waiting for the other to read This commit introduces a buffered pipe implementation that allows writes to proceed up to a configurable limit (10MB) before blocking. If the buffer is exceeded, an error is returned rather than deadlocking. The 10MB limit is far more than needed for pack negotiation - even with 1000 refs, the data is typically under 100KB.
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Summary
The file transport uses in-process pipes to communicate between client and server. With unbuffered
io.Pipe, both sides can deadlock when cloning repositories with many refs (e.g., 300+ branches).The deadlock occurs because:
io.Pipehas zero buffer)Solution
This PR introduces a buffered pipe implementation that allows writes to proceed up to a configurable limit (10MB) before returning an error. If the buffer is exceeded,
ErrBufferFullis returned rather than deadlocking indefinitely.The 10MB limit is far more than needed for pack negotiation - even with 1000 refs, the data is typically under 100KB.
Changes
buffered_pipe.go: New buffered pipe implementation with configurable max sizeclient.go: Use buffered pipes for stdin and stdout instead ofio.Pipebuffered_pipe_test.go: Tests for the buffered pipe implementationTesting
All existing file transport tests pass:
New tests added for the buffered pipe: