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https://issues.apache.org/jira/browse/HADOOP-11758?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14384371#comment-14384371
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Colin Patrick McCabe commented on HADOOP-11758:
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I also wonder if we can do tracing at a level slightly above writeChunk.
writeChunk operates at the level of 512-byte chunks, but writes are often
larger than that.
If you look here:
{code}
private void writeChecksumChunks(byte b[], int off, int len)
throws IOException {
sum.calculateChunkedSums(b, off, len, checksum, 0);
for (int i = 0; i < len; i += sum.getBytesPerChecksum()) {
int chunkLen = Math.min(sum.getBytesPerChecksum(), len - i);
int ckOffset = i / sum.getBytesPerChecksum() * getChecksumSize();
writeChunk(b, off + i, chunkLen, checksum, ckOffset, getChecksumSize());
}
}
{code}
you can see that if we do a 4 kilobyte read, writeChunk will get called 8
times. But really it would be better just to have one span representing the
entire 4k write.
> Add options to filter out too much granular tracing spans
> ---------------------------------------------------------
>
> Key: HADOOP-11758
> URL: https://issues.apache.org/jira/browse/HADOOP-11758
> Project: Hadoop Common
> Issue Type: Improvement
> Components: tracing
> Reporter: Masatake Iwasaki
> Assignee: Masatake Iwasaki
> Priority: Minor
> Attachments: testWriteTraceHooks.html
>
>
> in order to avoid queue in span receiver spills
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