maria-developers team mailing list archive

[Pavel Ivanov <pivanof@xxxxxxxxxx>]

On Mon, Nov 18, 2013 at 6:26 AM, Kristian Nielsen
<knielsen@xxxxxxxxxxxxxxx> wrote:
> Pavel Ivanov <pivanof@xxxxxxxxxx> writes:
>
>> sql/log.cc has highly inconsistent pattern of accessing
>> rpl_global_gtid_binlog_state. In some places it's protected by mutex
>> rpl_global_gtid_binlog_state.LOCK_binlog_state, in some places it's
>> protected by global mutex LOCK_rpl_gtid_state, and in some places it's
>> not protected by any mutex at all. This is a bug that should be fixed,
>> right?
>
> Yes, agree, thanks for finding this.
>
>> I can file this in JIRA if you want, just wanted to let you know faster.
>
> I've filed it as MDEV-5306.
>
>> I've noticed this problem after one of our AddressSanitizer testing
>> bots reported that rpl_binlog_state::bump_seq_no_if_needed (called
>> from MYSQL_BIN_LOG::bump_seq_no_counter_if_needed) was using memory
>> from hash after it was already freed by rpl_binlog_state::reset
>> (called by MYSQL_BIN_LOG::reset_logs).
>
> Can you test again with the latest patch I've just pushed to 10.0-base?
> I looked briefly into making an mtr test case to catch this, but I did not see
> any easy way to do that. I went through the code to try and check all uses of
> rpl_binlog_state for proper locking, but it would be nice to get a
> confirmation that I did not miss anything.

As you may guess this confirmation will be fuzzy. Of course I'll
include http://bazaar.launchpad.net/~maria-captains/maria/10.0-base/revision/3936
into our tree and will monitor testing bots, but I saw the problem
only once so far...

<rant>
I'm sure I would be able to get a definitive confirmation if
MySQL/MariaDB could be tested with ThreadSanitizer. But at the moment
it's a complete hell full of benign races (most of which seem to be in
InnoDB), so it's impossible to filter out real races from developers'
ignorance... :(
I hope sometimes someone will see importance of this problem and will
have time to chase and fix everything...
</rant>


Pavel