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, - Kristian. Kristian Nielsen <[email protected]> writes: > revision-id: 49b25020ef512866751f192b91d8439670d0430b > (mariadb-10.1.8-257-g49b2502) > parent(s): be2b833c426b420073c50564125049e2b4a95e8b > committer: Kristian Nielsen > timestamp: 2016-09-09 18:09:59 +0200 > message: > > Fix assertion/hang in read_init_file() > > If there are other threads running (for example binlog background > thread), then the thread count may not drop to zero at the end of > do_handle_bootstrap(). This caused an assertion and missing wakeup of > the main thread. The missing wakeup is because THD::~THD() only > signals the COND_thread_count mutex when the number of threads drops > to zero. > > Signed-off-by: Kristian Nielsen <[email protected]> > > --- > sql/sql_parse.cc | 13 ++++++++++++- > 1 file changed, 12 insertions(+), 1 deletion(-) > > diff --git a/sql/sql_parse.cc b/sql/sql_parse.cc > index 7263082..6baff31 100644 > --- a/sql/sql_parse.cc > +++ b/sql/sql_parse.cc > @@ -1082,9 +1082,20 @@ void do_handle_bootstrap(THD *thd) > end: > in_bootstrap= FALSE; > delete thd; > + if (!opt_bootstrap) > + { > + /* > + We need to wake up main thread in case of read_init_file(). > + This is not done by THD::~THD() when there are other threads running > + (binlog background thread, for example). So do it here again. > + */ > + mysql_mutex_lock(&LOCK_thread_count); > + mysql_cond_broadcast(&COND_thread_count); > + mysql_mutex_unlock(&LOCK_thread_count); > + } > > #ifndef EMBEDDED_LIBRARY > - DBUG_ASSERT(thread_count == 0); > + DBUG_ASSERT(!opt_bootstrap || thread_count == 0); > my_thread_end(); > pthread_exit(0); > #endif > _______________________________________________ > commits mailing list > [email protected] > https://lists.askmonty.org/cgi-bin/mailman/listinfo/commits _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
