[unixODBC-support] locking issue

Chauhan Bhavik-A20762 bhavik at motorola.com
Fri Dec 21 09:29:05 GMT 2007


Hi Nick,

This is what the stack we got it by pstack..while it was blocking 
I think if MySQL server is still 99.9% and not able to handle further
queries on the TCP connection established it should throw an error
rather that blocking at reading as the stack show

We use libmyodbc3-3.51.14.so as a driver 

Thread 64 (Thread 4152904624 (LWP 30228)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0x004d113e in __lll_mutex_lock_wait () from /lib/tls/libpthread.so.0
#2  0x004cdd9b in _L_mutex_lock_35 () from /lib/tls/libpthread.so.0
#3  0xf7883fe8 in ?? ()
#4  0x00c38d70 in ?? () from /usr/lib/libodbc.so.1
#5  0x00000000 in ?? ()
Thread 63 (Thread 4142414768 (LWP 30229)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0x004d113e in __lll_mutex_lock_wait () from /lib/tls/libpthread.so.0
#2  0x004cdd9b in _L_mutex_lock_35 () from /lib/tls/libpthread.so.0
#3  0xf6e82fe8 in ?? ()
#4  0x00c38d70 in ?? () from /usr/lib/libodbc.so.1
#5  0x00000000 in ?? ()
Thread 62 (Thread 4131924912 (LWP 30230)):
#0  0xffffe410 in __kernel_vsyscall ()
#1  0x004d13fb in __read_nocancel () from /lib/tls/libpthread.so.0
#2  0xf7b20239 in vio_read ()
#3  0xf7b202a0 in vio_read_buff ()
#4  0xf7b21b32 in my_net_read ()
#5  0xf7b2195e in my_net_read ()
#6  0xf7b1adb1 in cli_safe_read ()
#7  0xf7b1d760 in mysql_close ()
#8  0xf7b1d9d0 in mysql_real_query ()
#9  0xf7afff8e in mysql_query ()
#10 0xf7af5a3a in do_query ()
#11 0xf7af66d7 in my_SQLExecute ()
#12 0xf7af653c in SQLExecute ()
#13 0x00becce9 in SQLExecute () from /usr/lib/libodbc.so.1
#14 0x080996b4 in XXXLDBAccess::executeQuery ()
#15 0x080841c7 in XXXAccess::getHouseHoldAndPhNumInfo ()
#16 0x08051417 in XXX::processCallNotification ()
#17 0x08050cb8 in XXX::processMsg ()
#18 0x0806bb26 in XXX_FIFO::execute ()
#19 0x080d23f2 in SThreadFIFO::threadProc ()
#20 0x004cc341 in start_thread () from /lib/tls/libpthread.so.0
#21 0x003606fe in clone () from /lib/tls/libc.so.6
Thread 61 (Thread 4121435056 (LWP 30231)):

Regards,
Bhavik

-----Original Message-----
From: unixodbc-support-bounces at easysoft.com
[mailto:unixodbc-support-bounces at easysoft.com] On Behalf Of Nick Gorham
Sent: Thursday, December 20, 2007 8:24 PM
To: Support for the unixODBC project
Subject: Re: [unixODBC-support] locking issue

Chauhan Bhavik-A20762 wrote:

>Hi Nick,
>
>This problem is faced when mysql server is reaching to 99.9 % of CPU
>utilization. And all the threads within process is blocked with the
same
>stack as follow, then when the server is restarted it it's keeping up
>the processing.
>
>What could be the reason to be blocked?
>  
>

Don't know, I haven't seen it before. Maybe get 2.2.13pre to make sure 
its not a fixed issue, other than that check if its a driver issue, 
maybe add printfs around the mutex code, to ensure its not in the driver

instead of the driver manager. I have had hundreds of concurrent threads

running to test our drivers, and never seen that problem.

-- 
Nick Gorham
Easysoft Limited
http://www.easysoft.com, http://www.unixODBC.org

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