fix: use min instead of max when capping write buffer size to Int range#3914
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mbutrovich merged 1 commit intoapache:mainfrom Apr 8, 2026
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COMET_SHUFFLE_WRITE_BUFFER_SIZE is a Long (bytesConf) but the protobuf field is int32, so the value must be capped at Int.MaxValue. The code used .max(Int.MaxValue) which always returns Int.MaxValue (~2GB) regardless of the configured value. Should be .min(Int.MaxValue) to preserve smaller values while capping at the Int range.
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…ge (apache#3914) COMET_SHUFFLE_WRITE_BUFFER_SIZE is a Long (bytesConf) but the protobuf field is int32, so the value must be capped at Int.MaxValue. The code used .max(Int.MaxValue) which always returns Int.MaxValue (~2GB) regardless of the configured value. Should be .min(Int.MaxValue) to preserve smaller values while capping at the Int range.
andygrove
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…ge (#3914) (#3936) COMET_SHUFFLE_WRITE_BUFFER_SIZE is a Long (bytesConf) but the protobuf field is int32, so the value must be capped at Int.MaxValue. The code used .max(Int.MaxValue) which always returns Int.MaxValue (~2GB) regardless of the configured value. Should be .min(Int.MaxValue) to preserve smaller values while capping at the Int range.
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Which issue does this PR close?
Closes #.
Rationale for this change
COMET_SHUFFLE_WRITE_BUFFER_SIZEis aLong(configured viabytesConf) but the protobufShuffleWriter.write_buffer_sizefield isint32. The code converts with.max(Int.MaxValue).toInt, which always evaluates toInt.MaxValue(~2GB) regardless of the actual configured value. The intent was to cap the value atInt.MaxValue, which requires.min(Int.MaxValue).The practical impact is limited: the write buffer is a
Vec<u8>that grows organically and flushes when it exceeds the configured threshold. With a 2GB threshold, the buffer effectively never flushes early — it accumulates all serialized IPC bytes for a partition untilflush()is called at the end of processing. This means thespark.comet.exec.shuffle.writeBufferSizeconfig is silently ignored, but it does not cause excessive memory allocation since the buffer only grows to match the actual data written.What changes are included in this PR?
One-line fix:
.max(Int.MaxValue)→.min(Int.MaxValue)inCometNativeShuffleWriter.scala.How are these changes tested?
Existing tests. The fix is a straightforward logic correction with no behavioral change for values already within Int range (which is all practical values).