Huaisi Xu has posted comments on this change. Change subject: IMPALA-4740: Add option to use hdfsPread() for HDFS hedged reads ......................................................................
Patch Set 2: > > The HDFS-5776 JIRA mentions that it's implemented for the pread() > > code path, but it's not that clear. If you look at the code it's > > very clear that it only kicks in on the pread() code path: > > > > https://github.com/apache/hadoop/search?utf8=%E2%9C%93&q=isHedgedReadsEnabled > > I may be wrong again (as always), hdfspread is not pread. from > https://github.com/apache/hadoop/blob/f67237cbe7bc48a1b9088e990800b37529f1db2a/hadoop-hdfs-project/hadoop-hdfs-native-client/src/main/native/libhdfs/hdfs.c#L1426, > you can see hdfspread() invokes read(), and hdfsread() calls read() > as well, and in turn read() calls pread() as you can see in the > link you just quoted. So this new gflag is essentially ignored? > What did I miss here? I missed. it calls a different signature. hdfspread calls read(long position, byte[] buffer, int offset, int length). thanks for pointing it out.. -- To view, visit http://gerrit.cloudera.org:8080/5635 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: Iecc8b12aa20cbfe08f4ef6a08a191e49709d9525 Gerrit-PatchSet: 2 Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-Owner: Matthew Jacobs <[email protected]> Gerrit-Reviewer: Dan Hecht <[email protected]> Gerrit-Reviewer: Huaisi Xu <[email protected]> Gerrit-Reviewer: Internal Jenkins Gerrit-Reviewer: Matthew Jacobs <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-HasComments: No
