Adar Dembo has posted comments on this change. Change subject: KUDU-1601. Delete ancient UNDO delta blocks in the background ......................................................................
Patch Set 5: (2 comments) Mostly just passing through as I was interested to see the solution taken. http://gerrit.cloudera.org:8080/#/c/4363/5//COMMIT_MSG Commit Message: PS5, Line 15: The task was written to operate at the server level because the : UpdateStats() part of the task spends a budgeted amount of time opening : (initializing) undo delta blocks in order to read the stats from their : headers. Maybe I'm missing something obvious, but I don't see how the explanation (second half) justifies the assertion (first half). What is it about UpdateStats() doing I/O that forces the op to be server-level, or makes it more desirable? I agree with a comment JD made in chat: would it be possible to make opening of eager UNDO delta blocks an MM op in its own right? Doing I/O in UpdateStats() (regardless of at what level) seems weird; it has the potential to stall other cheap MM operations (such as log GC) if the I/O is blocked for a really long time. It also puts the I/O on the scheduler thread instead of on the MM operations thread(s). If you don't want to introduce two new ops, perhaps they can be "combined" such that Perform() either opens some UNDO blocks, or does ancient history GC, and we'll decide which approach to take during UpdateStats()? http://gerrit.cloudera.org:8080/#/c/4363/5/src/kudu/master/catalog_manager.cc File src/kudu/master/catalog_manager.cc: Line 2357: // The catalog manager has only one tablet peer. It's possible for sys_catalog_ to not yet be set, in which case this function should return an error (see GetTabletPeer()). -- To view, visit http://gerrit.cloudera.org:8080/4363 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: I0309bf7acfb6d018860c80f354012c3500da5c68 Gerrit-PatchSet: 5 Gerrit-Project: kudu Gerrit-Branch: master Gerrit-Owner: Mike Percy <mpe...@apache.org> Gerrit-Reviewer: Adar Dembo <a...@cloudera.com> Gerrit-Reviewer: David Ribeiro Alves <dral...@apache.org> Gerrit-Reviewer: Jean-Daniel Cryans <jdcry...@apache.org> Gerrit-Reviewer: Kudu Jenkins Gerrit-Reviewer: Mike Percy <mpe...@apache.org> Gerrit-Reviewer: Tidy Bot Gerrit-HasComments: Yes
