Comments on: How to CANCEL a query running in another session? http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/ Oracle troubleshooting, internals and performance tuning Thu, 09 Sep 2010 00:43:45 +0000 hourly 1 http://wordpress.org/?v=3.0.1 By: Sergei Romanenko http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4329 Sergei Romanenko Thu, 08 Apr 2010 05:15:08 +0000 http://blog.tanelpoder.com/?p=628#comment-4329 Tanel, thanks a lot! Now it's clear how it works. Tanel, thanks a lot! Now it’s clear how it works.

]]> By: Tanel Poder http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4326 Tanel Poder Wed, 07 Apr 2010 06:17:04 +0000 http://blog.tanelpoder.com/?p=628#comment-4326 <a href="#comment-4321" rel="nofollow">@Sergei Romanenko</a> Sergei, yep when connecting from *some* windows clients then the client tells Oracle during connect that it can not send urgent packets, thus Oracle switches to the out-of-band break polling (you can disable that with DISABLE_OOB parameter in sqlnet.ora, then you can't cancel a query at all). Yep in theory if you could make the windows client to somehow say Oracle server it supports urgent packets then oracle would set up the signal handler properly and you could use the URG signal to cancel the query... In practice I wouldn't waste time trying, especially in production... @Sergei Romanenko
Sergei, yep when connecting from *some* windows clients then the client tells Oracle during connect that it can not send urgent packets, thus Oracle switches to the out-of-band break polling (you can disable that with DISABLE_OOB parameter in sqlnet.ora, then you can’t cancel a query at all).

Yep in theory if you could make the windows client to somehow say Oracle server it supports urgent packets then oracle would set up the signal handler properly and you could use the URG signal to cancel the query… In practice I wouldn’t waste time trying, especially in production…

]]> By: Sergei Romanenko http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4321 Sergei Romanenko Tue, 06 Apr 2010 07:15:39 +0000 http://blog.tanelpoder.com/?p=628#comment-4321 Tanel, sorry for my delay in reply. Yes, you are right. When connecting from Linux client, "kill -URG" works. When connecting from Windows, it doesn't. And yes, the server process does a lot of poll() system calls. I reread the article, still not sure I understand the difference. Does it mean, when server process is started on behalf of win client, it doesn't register Urgent signal handler? Instead it polls the socket in the execution loop (quite often) to check if OCIBreak was sent by the client? If so, then in theory win client could fool the server process and pretend it was a linux/unix client and the "kill - URG" would work? Tanel, sorry for my delay in reply. Yes, you are right. When connecting from Linux client, “kill -URG” works. When connecting from Windows, it doesn’t. And yes, the server process does a lot of poll() system calls.

I reread the article, still not sure I understand the difference. Does it mean, when server process is started on behalf of win client, it doesn’t register Urgent signal handler? Instead it polls the socket in the execution loop (quite often) to check if OCIBreak was sent by the client? If so, then in theory win client could fool the server process and pretend it was a linux/unix client and the “kill – URG” would work?

]]> By: Tanel Poder http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4300 Tanel Poder Tue, 30 Mar 2010 02:34:17 +0000 http://blog.tanelpoder.com/?p=628#comment-4300 <a href="#comment-4294" rel="nofollow">@Sergei Romanenko</a> Sergei, it should work on Linux server as well. What's your client OS? If on Windows client OS, then at least when running from sqlplus, the kill -URG trick won't work as I explained in my post. Maybe in case of some other client app/OCI library versions the same applies. You can run strace on your server process and see whether it does a lot of poll() syscalls when you run something in the server, if yes, then the break by urgent signal handling has not been set up/requested by client. @Sergei Romanenko
Sergei, it should work on Linux server as well. What’s your client OS?

If on Windows client OS, then at least when running from sqlplus, the kill -URG trick won’t work as I explained in my post. Maybe in case of some other client app/OCI library versions the same applies. You can run strace on your server process and see whether it does a lot of poll() syscalls when you run something in the server, if yes, then the break by urgent signal handling has not been set up/requested by client.

]]> By: Sergei Romanenko http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4294 Sergei Romanenko Mon, 29 Mar 2010 18:15:17 +0000 http://blog.tanelpoder.com/?p=628#comment-4294 Does "kill -URG" work in Linux? I have long running query and tried: kill -URG 29086 kill -s SIGURG 29086 kill -s SIGINT 29086 kill -2 29086 - all of them were ignored by the process. I can cancel the query any moment by sending OCIBreak from the client program which started the query. Because many applications are not able to send OCIBreak, it will be nice to be able to cancel by "kill", but does it work in Linux or am I missing something? Does “kill -URG” work in Linux? I have long running query and tried:

kill -URG 29086
kill -s SIGURG 29086
kill -s SIGINT 29086
kill -2 29086

- all of them were ignored by the process. I can cancel the query any moment by sending OCIBreak from the client program which started the query. Because many applications are not able to send OCIBreak, it will be nice to be able to cancel by “kill”, but does it work in Linux or am I missing something?

]]> By: Blogroll Report 12/02/2009 – 19/02/2010 « Coskan’s Approach to Oracle http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4258 Blogroll Report 12/02/2009 – 19/02/2010 « Coskan’s Approach to Oracle Thu, 18 Mar 2010 16:45:11 +0000 http://blog.tanelpoder.com/?p=628#comment-4258 [...] 27-How to cancel a query running in another session? Tanel Poder-How to CANCEL a query running in another session? [...] [...] 27-How to cancel a query running in another session? Tanel Poder-How to CANCEL a query running in another session? [...]

]]> By: Noons http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-4044 Noons Sun, 07 Mar 2010 23:20:30 +0000 http://blog.tanelpoder.com/?p=628#comment-4044 Thanks for this one, Tanel. Had a chance to use it last Friday and it works a treat. Thanks for this one, Tanel. Had a chance to use it last Friday and it works a treat.

]]> By: Alex http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-3978 Alex Thu, 04 Mar 2010 17:10:38 +0000 http://blog.tanelpoder.com/?p=628#comment-3978 Hi Tanel, set event 10237 Hi Tanel,
set event 10237

]]> By: Fun query cancelling using TCP out-of-band signalling « Kirk Brocas' Oracle Stuff http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-3970 Fun query cancelling using TCP out-of-band signalling « Kirk Brocas' Oracle Stuff Wed, 03 Mar 2010 21:49:35 +0000 http://blog.tanelpoder.com/?p=628#comment-3970 [...] How to CANCEL a query running in another session? – Tanel Poder’s blog [...] [...] How to CANCEL a query running in another session? – Tanel Poder’s blog [...]

]]> By: Ben Prusinski http://blog.tanelpoder.com/2010/02/17/how-to-cancel-a-query-running-in-another-session/comment-page-1/#comment-3961 Ben Prusinski Tue, 02 Mar 2010 03:55:34 +0000 http://blog.tanelpoder.com/?p=628#comment-3961 Interesting! I look forward to meeting you at Hotsos next week. Cheers, Ben Interesting! I look forward to meeting you at Hotsos next week.

Cheers,
Ben

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