Voytek:
Found the problem with your signal 11 with strange traces from inside
LinuxThreads. This was a hard concurrency bug - the problem was that a memory
reference passed to pthread_create was getting invalidated by the thread that
pthread_create was launching before pthread_create would right to that value.
Took me a while to figure this out - I have scrutinized the entire thread
creation mechanism in LinuxThreads suspecting a bad mmap or munmap somewhere
before I realized the problem had nothing to do with LinuxThreads internal
code.
I believe the problem has existed for as long as MySQL has been around - back
then the machines were just not fast enough to make this condition happen
frequently enough for someone to be able to create a repeatable case. I have
fixed it by extending the critical region. Here is the patch:
--- 1.155/sql/mysqld.cc Sat Mar 24 16:02:25 2001
+++ edited/mysqld.cc Sat Mar 24 23:05:23 2001
@@ -2091,7 +2091,6 @@
threads.append(thd);
DBUG_PRINT("info",(("creating thread %d"), thd->thread_id));
thd->connect_time = time(NULL);
- (void) pthread_mutex_unlock(&LOCK_thread_count);
if ((error=pthread_create(&thd->real_id,&connection_attrib,
handle_one_connection,
(void*) thd)))
@@ -2099,7 +2098,6 @@
DBUG_PRINT("error",
("Can't create thread to handle request (error %d)",
error));
- (void) pthread_mutex_lock(&LOCK_thread_count);
thread_count--;
thd->killed=1; // Safety
(void) pthread_mutex_unlock(&LOCK_thread_count);
@@ -2110,6 +2108,8 @@
(void) pthread_mutex_unlock(&LOCK_thread_count);
DBUG_VOID_RETURN;
}
+
+ (void) pthread_mutex_unlock(&LOCK_thread_count);
}
}
DBUG_PRINT("info",(("Thread %d created"), thd->thread_id));
The fix will be available in 3.23.36.
--
MySQL Development Team
__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Sasha Pachev <[EMAIL PROTECTED]>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, http://www.mysql.com/
/_/ /_/\_, /___/\___\_\___/ Provo, Utah, USA
<___/
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