Andrew Wong has posted comments on this change. ( http://gerrit.cloudera.org:8080/13975 )
Change subject: Consider the available space when selecting data dirs for blocks. ...................................................................... Patch Set 9: > Patch Set 8: > > > (9 comments) > > > > I'll look into the test failure some more. If I check out this > > patch, I see it failing a small percentage (2-6%) of the time. > > About the failure in DiskErrorITest.TestFailDuringScanWorkload. IIUC, it only > inject the disk failure in data_dir[1], and after the reflush check change, > it may be remove from the candidate dirs. So it may not trigger the failure > and so the test will failure. I added some logging and think I understand what's going on. When we first create the tablets, we always refresh the space, and this necessarily isn't atomic between the data dirs, so we can sometimes end up with the data directories registering that they have different amounts of available space, even though they share the same disk. When this happens, because there are only three directories, this implementation of PO2C might end up completely ignoring the data dir with the least amount of space in it. So I see two paths forward for this. Either: 1) update the implementation of PO2C to sometimes select the data dir with the least space. For example, select two random indices (may be the same) and compare the available space (compared to what we have now, which always compares two different data directories). OR... 2) update disk_failure-itest to inject failures into two data directories instead of one. With the current PO2C implementation, it's a safe bet that killing two data dirs will touch blocks. -- To view, visit http://gerrit.cloudera.org:8080/13975 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: kudu Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I194c4965ee64aed728e3b84e684c04d445cbe529 Gerrit-Change-Number: 13975 Gerrit-PatchSet: 9 Gerrit-Owner: ZhangYao <triplesheep0...@gmail.com> Gerrit-Reviewer: Adar Dembo <a...@cloudera.com> Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com> Gerrit-Reviewer: Kudu Jenkins (120) Gerrit-Reviewer: Yingchun Lai <405403...@qq.com> Gerrit-Reviewer: ZhangYao <triplesheep0...@gmail.com> Gerrit-Comment-Date: Fri, 09 Aug 2019 20:58:12 +0000 Gerrit-HasComments: No
