Hi! On Fri, Sep 9, 2016 at 7:31 PM, Kristian Nielsen <[email protected]> wrote: > Monty, > > My latest push uncovered a problem in the 10.2 tree; however the problem was > there before, just not triggered by the testsuite. I pushed the below patch > to fix the test failures in Buildbot, but I am not sure it is the correct > solution, so please check it. > > It appears the problem was introduced with this patch: > > commit 3d4a7390c1a94ef6e07b04b52ea94a95878cda1b > Author: Monty <[email protected]> > Date: Mon Feb 1 12:45:39 2016 +0200 > > MDEV-6150 Speed up connection speed by moving creation of THD to new > thread > > diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc > index 84f0c63..355f62d 100644 > --- a/sql/sql_parse.cc > +++ b/sql/sql_parse.cc > @@ -844,12 +844,13 @@ void do_handle_bootstrap(THD *thd) > delete thd; > > #ifndef EMBEDDED_LIBRARY > - thread_safe_decrement32(&thread_count); > + DBUG_ASSERT(thread_count == 1); > in_bootstrap= FALSE; > - > - mysql_mutex_lock(&LOCK_thread_count); > - mysql_cond_broadcast(&COND_thread_count); > - mysql_mutex_unlock(&LOCK_thread_count); > + /* > + dec_thread_count will signal bootstrap() function that we have ended as > + thread_count will become 0. > + */ > + dec_thread_count(); > my_thread_end(); > pthread_exit(0); > #endif > > The problem is that do_handle_bootstrap is not only used for bootstrap - it > is also used for read_init_file(). In the latter case, it is _not_ > guaranteed that thread_count will drop to zero. For example, the binlog > background thread might be running. You can see this in 10.2 (before my > just-pushed fix) by running
> ./mtr main.init_file --mysqld=--log-bin=mysql-bin > > It will assert, or hang if assert is disabled. > > To get rid of the failures in Buildbot, I pushed the below patch. I think > the patch is perfectly safe. However, maybe there is a better way - it seems > a bit messy, mixing bootstrap and read_init_file() and having these > if (opt_bootstrap) conditions. And maybe there are other problems caused by > this as well that I did not notice? As I am not much familiar with how this > thread count checking / bootstrap / init file handling works. Thanks for the patch and for finding the bug! However, Serg already removed the thread count handling from do_handle_bootstrap. I will today check if the problem still exists and if yes, fix it by always sending the broadcast. (A quick look suggest it still exist). Regards, Monty _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
