Re: segmentation violation only during SELECT of a file.

[Jim Idle]

Pawel (privately) wrote: Hi Jim, Dnia 17-03-2009 o godz. 0:37 Jim Idle napisał(a): Pawel (privately) wrote: Hi, This is not a file corruption I think. Please try to observe memory allocation during runing this select. Use MW42 -m -P<port_number_of_your_session> to monitor MemFree and MemUsed values. Let us know what is behaviour (how they change). I guess that you may notice pretty high MemFree. Please check also ulimit (process limits) and LDR_CNTRL in order to validate if SIGSEGV does not come from exceeded limits. I think it is just running out of memory. (Finally) I think that change of malloc options should help you (try with "export MALLOCTYPE=watson" or "export MALLOCTYPE=buckets"). Pawel, Did you ever run your tests using teh Watson allocator? No, we did not tried Watson for a longer period of time. We have however tried MALLOCOPTION=disclaim on test area and noticed real slow down of system. Yes  - disclaim will be very slow. COB was run over a weekend. It was performing relatively slow and one of the jobs could not complete. People called me and not knowing details I asked to revert .profile settings back to standard allocator. Then restarted COB progressed much faster (as usual) and completed without troubles. So diclaim is introducing some (significant) overhead to our batch processes. I think that we should test Watson more. I think that you would be well advised to just switch to it. I do not see much benefit from Watson allocator and think that in our situation we could benefit from "disclaim" option No, it is the opposite I think. disclaim isn't going to be very useful. (but it is introducing too much overhead). I think that we will try Watson one day, but it is not high priorty. It should be :-) We have been running "buckets" allocator for a month on our main test area and did not observe much benfits. We do not monitor COBs well however and it was already raised by me. No - it is better than not having the option, but the allocation patterns don't really help with buckets except to try and keep allocations separated out a bit. Jim --~--~---------~--~----~------------~-------~--~----~ Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to jBASE@googlegroups.com To unsubscribe, send email to jbase-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/jBASE?hl=en -~----------~----~----~----~------~----~------~--~---