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From "Tianyi Wang (Code Review)" <>
Subject [Impala-ASF-CR] IMPALA-6121: remove I/O mgr request context cache
Date Wed, 01 Nov 2017 21:47:58 GMT
Tianyi Wang has posted comments on this change. ( )

Change subject: IMPALA-6121: remove I/O mgr request context cache

Patch Set 4:

Commit Message:
PS4, Line 12: from TCMalloc's thread caches should scale much better than a
Though reader_context_ is not frequently allocated in current code, theoretically for reducing
allocation won't it be better to store DiskIoRequestContext directly (or boost::optional<>
for a "nullable cell")?
File be/src/runtime/disk-io-mgr-reader-context.h:
PS4, Line 274:       __sync_synchronize();
Just a question - Does b need to be atomic here? If it does not generate a MOV then this __sync_synchronize
might not be effective as well
PS4, Line 319:       if (!is_on_queue_ && num_threads_in_op_.Load() == 0 &&
!done_) {
The return value of Add can be used to remove this Load
File be/src/runtime/
PS4, Line 251:   unique_ptr<DiskIoRequestContext> writer = io_mgr.RegisterContext(NULL);

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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I91414eceaa4938fccd74686fe6bebede6ef36108
Gerrit-Change-Number: 8408
Gerrit-PatchSet: 4
Gerrit-Owner: Tim Armstrong <>
Gerrit-Reviewer: Michael Ho <>
Gerrit-Reviewer: Tianyi Wang <>
Gerrit-Reviewer: Tim Armstrong <>
Gerrit-Comment-Date: Wed, 01 Nov 2017 21:47:58 +0000
Gerrit-HasComments: Yes

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