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tranport: Reduce heap allocs by setting BufferSlice capacity #8797

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Merged
arjan-bal merged 3 commits into from
Jan 7, 2026
Merged

tranport: Reduce heap allocs by setting BufferSlice capacity #8797

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8859e73
improve estimate for bufferslice length
arjan-bal Jan 2, 2026
3826f6e
clamp max buffer size
arjan-bal Jan 5, 2026
b01f07f
avoid early return, specify capacitly limit directly
arjan-bal Jan 6, 2026
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10 changes: 10 additions & 0 deletions internal/transport/transport.go
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Original file line number Diff line number Diff line change
Expand Up @@ -384,6 +384,16 @@ func (s *Stream) read(n int) (data mem.BufferSlice, err error) {
if er := s.trReader.er; er != nil {
return nil, er
}
if n == 0 {
return data, nil
}
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// gRPC Go accepts data frames with a maximum length of 16KB. Larger
// messages must be split into multiple frames. We pre-allocate the
// buffer to avoid resizing during the read loop, but cap the initial
// capacity to 128 frames (2MB) to prevent over-allocation or panics
// when reading extremely large streams.
allocCap := min((n-1)/http2MaxFrameLen+1, 2*1024*1024/http2MaxFrameLen)
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data = make(mem.BufferSlice, 0, allocCap)
s.readRequester.requestRead(n)
for n != 0 {
buf, err := s.trReader.Read(n)
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