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Kristian Nielsen

Nov 25, 2010, 8:55:07 AM11/25/10
I discovered a bug in INFORMATION_SCHEMA.INNODB_LOCKS in XtraDB (and InnoDB):

The bug causes test failures in our Buildbot, so it is important for us to
include it in MariaDB. However, I wanted to coordinate with Percona-Server
developers before merging it in case you want to include it in Percona-Server
(I put BSD in the patch); also if you could take a look at the patch and point
out any problems, that would be much appreciated.

The bug is that there is a race condition in the code that is supposed to
restrict updates to the INNODB_LOCKS table to every 100 milliseconds (as
updating the table causes contention on the kernel_mutex). This makes it
possible for the table to not be updated for much longer than 100
milliseconds; if the table is queried sufficiently frequently, it will keep
returning the same old data. It is also possible for the table to be updated
too frequently if accessed simultaneously by many connections in parallel.

- Kristian.


Vadim Tkachenko

Nov 25, 2010, 12:07:28 PM11/25/10
Kristian ,


Bug assigned to Alexey and we will merge fix soon.

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Vadim Tkachenko, CTO, Percona Inc.
Phone +1-888-401-3403,  Skype: vadimtk153
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