Adar Dembo has posted comments on this change. ( http://gerrit.cloudera.org:8080/11190 )
Change subject: file_cache: stop using sync_on_close when reopening evicted files ...................................................................... Patch Set 2: (2 comments) http://gerrit.cloudera.org:8080/#/c/11190/2//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/11190/2//COMMIT_MSG@11 PS2, Line 11: However, with its removal in commit 9a07b2fed, sync_on_close=true : should no longer be necessary for correctness. > hm, I'm having trouble paging this back in. Yes, that is the expectation, but I can't imagine how it would have been safe to rely on the previous state of affairs for durability. Suppose you were using the file cache but your fileset was small enough that files were never evicted; if you didn't call Sync yourself, you didn't get durability. So sure, I can add a comment, but the new semantics don't seem any different from the non file-cached world: if you want durability, you need to Sync (or you need to open your files with sync_on_close=true, but the file cache doesn't let you do that). http://gerrit.cloudera.org:8080/#/c/11190/2//COMMIT_MSG@16 PS2, Line 16: An unnecessary fdatasync system call should no-op, but maybe : that's not the case on older kernels? > hm, that's interesting. Do you think maybe the file had been modified by so Yeah that's a conceivable explanation. Or maybe on old kernels an fdatasync was always at least a seek, and since I was hammering this particular server's disk, these "no-op" fdatasyncs were affected. -- To view, visit http://gerrit.cloudera.org:8080/11190 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I845f39ea202ec0cb46ce8e841c6cfb6c3a8dad2c Gerrit-Change-Number: 11190 Gerrit-PatchSet: 2 Gerrit-Owner: Adar Dembo <[email protected]> Gerrit-Reviewer: Adar Dembo <[email protected]> Gerrit-Reviewer: Alexey Serbin <[email protected]> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Todd Lipcon <[email protected]> Gerrit-Comment-Date: Fri, 10 Aug 2018 22:25:04 +0000 Gerrit-HasComments: Yes
