Hello Alexey Serbin, Kudu Jenkins,
I'd like you to reexamine a change. Please visit
http://gerrit.cloudera.org:8080/7996
to look at the new patch set (#3).
Change subject: KUDU-2137: protect against concurrent schema version change and
tablet drop
......................................................................
KUDU-2137: protect against concurrent schema version change and tablet drop
Try as I might, I could not reproduce the failure in the bug report. I
looped the failed test several thousand times. I also looped the entire
alter_table-test suite a thousand times. Finally, I wrote a unit test that
hammers one table with concurrent add column, add partition, and drop
partition operations. Nothing worked.
So, here's my best guess at what's going on: if a tablet is dropped
while the master is processing its report, it's conceivable that we could
wind up in TabletInfo::set_reported_schema_version() with the table spinlock
held just after TableInfo::AddRemoveTablets() dropped the tablet. This would
cause us to decrement the tablet's "old" schema version from the table's
count map twice: once when dropping the tablet and a second time in
set_reported_schema_version().
The fix is straight-forward: after acquiring both spinlocks, double check
that the tablet is still a member of the table. We need to take the tablet
metadata lock to do this, but the saving grace is that tablet partition keys
are immutable, so this lock acquisition needn't overlap with the spinlocks.
Change-Id: I371fc310a97ae94ec2ebf04405db99c5f2937e1a
---
M src/kudu/master/catalog_manager.cc
1 file changed, 21 insertions(+), 2 deletions(-)
git pull ssh://gerrit.cloudera.org:29418/kudu refs/changes/96/7996/3
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Gerrit-MessageType: newpatchset
Gerrit-Change-Id: I371fc310a97ae94ec2ebf04405db99c5f2937e1a
Gerrit-PatchSet: 3
Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-Owner: Adar Dembo <[email protected]>
Gerrit-Reviewer: Adar Dembo <[email protected]>
Gerrit-Reviewer: Alexey Serbin <[email protected]>
Gerrit-Reviewer: Dan Burkert <[email protected]>
Gerrit-Reviewer: Kudu Jenkins
Gerrit-Reviewer: Todd Lipcon <[email protected]>
