7 Dec
2009
7 Dec
'09
4:06 p.m.
Hi Kristian & Vlad,
The crash also occurs immediately if MariaDB is started with an
unknown command line parameter.
In this case the server shuts down on startup, and new_thd-
>variables.table_plugin is NULL as described below.
On Dec 7, 2009, at 1:34 PM, Kristian Nielsen wrote:
> Vladimir Kolesnikov <vladimir@primebase.org> writes:
>
>> Unfortunately I cannot repeat the problem on my machine. Can you
>> please put the branch to the debian box that you gave earlier access
>> to?
>
> Yes.
>
> There is now a build directory on the box:
>
> /home/buildbot/shutdown-crash/mysql-5.1.41-MariaDB-beta/
>
> (I pushed the corresponding bzr version to
> lp:~knielsen/maria/maria-pbxt-shutdown-crash. This is a merge of
> PBXT into
> MariaDB).
>
> I built using
>
> BUILD/compile-pentium-max
>
> I get the test failure repeatably with this:
>
> (cd mysql-test && perl mysql-test-run.pl mysqld_option_err)
>
> It does not seem to fail the same way every time, but it does seem
> to fail
> everytime I run it.
>
> Let me know if you need anything else.
>
> Thanks again for looking into this!
>
> - Kristian.
>
>> Kristian Nielsen wrote:
>>> [I Cc'ed Paul, let me know if there is another prefered way of
>>> communicating,
>>> like using Launchpad bugs or some mailing list]
>>>
>>> Vladimir Kolesnikov <vladimir@primebase.org> writes:
>>>
>>>
>>>> "Crash during shutdown (need help from PBXT team)"
>>>>
>>>> can you provide any details?
>>>>
>>>
>>> Yes, of course! Just been busy with other stuff, but very happy
>>> that you
>>> mention it on your own initiative!
>>>
>>> Basically, after merging PBXT I see crashes in the
>>> main.mysqld_option_err test
>>> case. Here is an example build from Buildbot showing this:
>>>
>>> http://askmonty.org/buildbot/builders/debian5-i386-fulltest/builds/52
>>> http://askmonty.org/buildbot/builders/debian5-i386-fulltest/builds/52/steps/test_4/logs/stdio
>>>
>>> The failure appears to be somewhat random, but I was able to
>>> repeat it easily
>>> enough locally using a release build. Debug build did not seem to
>>> show the
>>> problem.
>>>
>>> The issue is with the fix that Paul pushed for Bug#489088:
>>>
>>> https://bugs.launchpad.net/pbxt/+bug/489088
>>>
>>> === modified file 'storage/pbxt/src/myxt_xt.cc'
>>> --- storage/pbxt/src/myxt_xt.cc 2009-11-27 15:37:02 +0000
>>> +++ storage/pbxt/src/myxt_xt.cc 2009-12-01 09:50:46 +0000
>>> @@ -3041,6 +3041,14 @@ xtPublic MX_CHARSET_INFO *myxt_getcharse
>>> return (MX_CHARSET_INFO *)&my_charset_utf8_general_ci;
>>> }
>>> +#ifdef DBUG_OFF
>>> +//typedef struct st_plugin_int *plugin_ref;
>>> +#define REF_MYSQL_PLUGIN(x) (x)
>>> +#else
>>> +//typedef struct st_plugin_int **plugin_ref;
>>> +#define REF_MYSQL_PLUGIN(x) (*(x))
>>> +#endif
>>> +
>>> xtPublic void *myxt_create_thread()
>>> {
>>> #ifdef DRIZZLED
>>>
>>> + LEX_STRING& plugin_name = REF_MYSQL_PLUGIN(new_thd-
>>> >variables.table_plugin)->name;
>>> + if ((plugin_name.length == 4) && (strncmp(plugin_name.str,
>>> "PBXT", plugin_name.length) == 0)) {
>>> + REF_MYSQL_PLUGIN(new_thd->variables.table_plugin)->ref_count--;
>>> + }
>>> new_thd->thread_stack = (char *) &new_thd;
>>> new_thd->store_globals();
>>> lex_start(new_thd);
>>>
>>> This code crashes because new_thd->variables.table_plugin is NULL
>>> at this
>>> point in the code (or at least sometimes is).
>>>
>>> So this problem is similar to the previous problem handled just
>>> above in the
>>> code with global_system_variables.table_plugin being NULL.
>>>
>>> I tried a patch like this:
>>>
>>> === modified file 'storage/pbxt/src/myxt_xt.cc'
>>> --- storage/pbxt/src/myxt_xt.cc 2009-12-01 09:50:46 +0000
>>> +++ storage/pbxt/src/myxt_xt.cc 2009-12-04 21:41:25 +0000
>>> @@ -3112,10 +3112,15 @@ xtPublic void *myxt_create_thread()
>>> * references to the PBXT plugin object and will effectively
>>> deadlock the plugin so * that server will have to force
>>> plugin shutdown. To avoid deadlocking and forced shutdown * we
>>> must dereference the plugin after creating THD objects.
>>> + * Similarly to global_system_variables.table_plugin as
>>> described above,
>>> + * new_thd->valriables.table_plugin can also become NULL due to
>>> shutdown.
>>> */
>>> - LEX_STRING& plugin_name = REF_MYSQL_PLUGIN(new_thd-
>>> >variables.table_plugin)->name;
>>> - if ((plugin_name.length == 4) && (strncmp(plugin_name.str,
>>> "PBXT", plugin_name.length) == 0)) {
>>> - REF_MYSQL_PLUGIN(new_thd->variables.table_plugin)->ref_count--;
>>> + plugin_ref table_plugin = new_thd->variables.table_plugin;
>>> + if (table_plugin) {
>>> + LEX_STRING& plugin_name = REF_MYSQL_PLUGIN(table_plugin)->name;
>>> + if ((plugin_name.length == 4) && (strncmp(plugin_name.str,
>>> "PBXT", plugin_name.length) == 0)) {
>>> + REF_MYSQL_PLUGIN(table_plugin)->ref_count--;
>>> + }
>>> }
>>> new_thd->thread_stack = (char *) &new_thd;
>>> new_thd->store_globals();
>>>
>>> So this fixes the crashes, but of course re-introduces the
>>> original problem in
>>> Bug#489088 with warnings about forced shutdown.
>>>
>>> I think you should be able to repeat the problem easily enough on
>>> Linux with a
>>> non-debug build running the test main.mysqld_option_err, but if
>>> not let me
>>> know and I will help set something up.
>>>
>>> - Kristian.
>>>
>>
>>
>> _______________________________________________
>> Mailing list: https://launchpad.net/~maria-developers
>> Post to : maria-developers@lists.launchpad.net
>> Unsubscribe : https://launchpad.net/~maria-developers
>> More help : https://help.launchpad.net/ListHelp
>
> _______________________________________________
> Mailing list: https://launchpad.net/~maria-developers
> Post to : maria-developers@lists.launchpad.net
> Unsubscribe : https://launchpad.net/~maria-developers
> More help : https://help.launchpad.net/ListHelp
--
Paul McCullagh
PrimeBase Technologies
www.primebase.org
www.blobstreaming.org
pbxt.blogspot.com