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From "Masatake Iwasaki (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-9576) HTrace: collect path/offset/length information on read and write operations
Date Tue, 05 Jan 2016 09:23:39 GMT

    [ https://issues.apache.org/jira/browse/HDFS-9576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15082697#comment-15082697
] 

Masatake Iwasaki commented on HDFS-9576:
----------------------------------------

Thanks for working on this, [~zhz]. I tried the 01 patch and checked that the annotations
are properly set in spans.

{code}
@@ -209,7 +209,7 @@ protected TraceScope createWriteTraceScope() {
   private void writeChecksumChunks(byte b[], int off, int len)
   throws IOException {
     sum.calculateChunkedSums(b, off, len, checksum, 0);
-    TraceScope scope = createWriteTraceScope();
+    TraceScope scope = createWriteTraceScope(len);
{code}

The {{len}} of "DFSOutputStream#write" span is basically size of internal buffer of FSOutputSummer
and constant (4608) most of the time. Do you have specific usecase for this?

For read, if the length is useful, recording the number of bytes actually read (which is return
value of read) as annotation might be helpful too.


> HTrace: collect path/offset/length information on read and write operations
> ---------------------------------------------------------------------------
>
>                 Key: HDFS-9576
>                 URL: https://issues.apache.org/jira/browse/HDFS-9576
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: hdfs-client, tracing
>    Affects Versions: 2.7.1
>            Reporter: Zhe Zhang
>            Assignee: Zhe Zhang
>         Attachments: HDFS-9576.00.patch, HDFS-9576.01.patch
>
>




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