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Application 'hang' and high 'btr0sea.c' error message captured
Posted by: Tan Daniel ()
Date: March 20, 2012 07:57PM

Hi There,

Would like to seek you guys advice, we have a Production environment with estimated about 300-500+ concurrent user during peak hours (month end / start of month).
Normal hours should be around 100+ concurrent user.

We experienced that our application 'hang' and become very slow & unresponsive during almost every month end or the start of the month whereby many user querying data for reporting & also updating on status etc.

The only temporary workaround for us is either to Kill all MySQL queries in the processlist or restart the MySQL or restart Tomcat (application).

During the 'hang', I show the InnoDB status and noticed that there is huge Semaphores locking occurred as below:-

OS WAIT ARRAY INFO: reservation count 14149497, signal count 1164183
--Thread 568 has waited at G:\\mysql-5.1.42-winbuild\\mysql-community-nt-5.1.42-build\\storage\\innobase\\include\\sync0rw.ic line 360 for 0.00 seconds the semaphore:
Mutex at 0CBB1298 created file .\\btr\\btr0sea.c line 139, lock var 1
waiters flag 1
--Thread 400 has waited at .\\btr\\btr0sea.c line 1277 for 0.00 seconds the semaphore:
S-lock on RW-latch at 0CBB1280 created in file .\\btr\\btr0sea.c line 139
a writer (thread id 400) has reserved it in mode wait exclusive
number of readers 1, waiters flag 1
Last time read locked in file .\\row\\row0sel.c line 3452
Last time write locked in file .\\btr\\btr0sea.c line 1277
--Thread 7384 has waited at .\\sync\\sync0rw.c line 288 for 0.00 seconds the semaphore:
Mutex at 0CBB1298 created file .\\btr\\btr0sea.c line 139, lock var 1
waiters flag 1
--Thread 7516 has waited at .\\sync\\sync0rw.c line 288 for 0.00 seconds the semaphore:
Mutex at 0CBB1298 created file .\\btr\\btr0sea.c line 139, lock var 1
waiters flag 1
--Thread 7716 has waited at .\\sync\\sync0rw.c line 288 for 0.00 seconds the semaphore:
Mutex at 0CBB1298 created file .\\btr\\btr0sea.c line 139, lock var 1
waiters flag 1
--Thread 7852 has waited at .\\sync\\sync0rw.c line 288 for 0.00 seconds the semaphore:
Mutex at 0CBB1298 created file .\\btr\\btr0sea.c line 139, lock var 1
--Thread 2520 has waited at G:\\mysql-5.1.42-winbuild\\mysql-community-nt-5.1.42-build\\storage\\innobase\\include\\sync0rw.ic line 243 for 0.00 seconds the semaphore:
Mutex at 0CBB1298 created file .\\btr\\btr0sea.c line 139, lock var 1
waiters flag 1
wait has ended
Mutex spin waits 0, rounds 278750543, OS waits 12260251
RW-shared spins 1691867, OS waits 1134090; RW-excl spins 145720, OS waits 51961

This is only a part of the InnoDB status. There is 48 btr0sea errors in the actual message. Would any experts able to advise what is going wrong with this error indicator?

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Subject Views Written By Posted
Application 'hang' and high 'btr0sea.c' error message captured 1697 Tan Daniel 03/20/2012 07:57PM
Re: Application 'hang' and high 'btr0sea.c' error message captured 796 Tan Daniel 03/21/2012 07:46PM
Re: Application 'hang' and high 'btr0sea.c' error message captured 783 Rick James 03/21/2012 08:56PM
Re: Application 'hang' and high 'btr0sea.c' error message captured 748 Tan Daniel 04/03/2012 04:22AM


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