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<== Date ==> <== Thread ==>

Subject: RE: Fanout to Sub Records in a Different IOC Causes Core Dump
From: "Poff, Mark A" <mark.a.poff@boeing.com>
To: "Konrad, Martin" <konrad@frib.msu.edu>, "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>, Andrew Johnson <anj@aps.anl.gov>
Cc: "Poff, Mark A" <mark.a.poff@boeing.com>
Date: Fri, 10 Oct 2014 10:38:44 +0000

Andrew and Martin (and EPICS community),

 

After experiencing the repeated crashes and examining a memory dump to the extent necessary to determine where they occurred (according to gdb, it was in camessage.c, line #1344, EPICS v3.14.12.3), I modified the databases to not use fanout records and moved on with my work - and committed the programming sin of not keeping a copy of the failed configuration.  Sure enough, when I tried to recreate the failure scenario yesterday - no crash occurred.  I know the cpp processes were the same (the only changes there were a couple of printf debug statements) but besides modifying the .db files I had also touched the .dbd file and the st.cmd file (we use a customized version) and probably a couple of other things.  The only conclusion I can find is that I’ve missed some small, but significant change I made which somehow contributed to the problem.

 

I apologize for raising a concern and then not being able to back it up.  The schedule here prohibits me from spending much more time researching this issue, but I will continue to pursue it as time permits and will let you know if I can get the core to recur.

 

-Mark Poff

 

-----Original Message-----
From: Konrad, Martin [mailto:konrad@frib.msu.edu]
Sent: Thursday, October 09, 2014 4:04 PM
To: Poff, Mark A; tech-talk@aps.anl.gov
Subject: Re: Fanout to Sub Records in a Different IOC Causes Core Dump

 

Hi Mark,

> If you can't, take a look at how much stack space your

> Process1_routine subroutine needs, running out of stack space is one

> possible cause for this kind of strange behaviour in addition to the

> usual kinds of problems. A full stack trace for all threads when the

> crash happens would also help us help you (type 'thread apply all bt'

> in gdb).

Keep in mind that the stack trace could be corrupted. You might want to run with a trivial subroutine for testing.

 

In addition to that it's always a good idea to write a short test program that calls the subroutine function with some test values. You can run this test program with

 

valgrind --tool=memcheck <your_test_program>

 

to see if it is writing to memory it should not write to.

 

Regards,

 

Martin

 

--

Martin Konrad

Control System Engineer

Facility for Rare Isotope Beams

Michigan State University

640 South Shaw Lane

East Lansing, MI 48824-1321, USA

Tel. 517-908-7253

Email: konrad@frib.msu.edu


References:
RE: Fanout to Sub Records in a Different IOC Causes Core Dump Poff, Mark A
Re: Fanout to Sub Records in a Different IOC Causes Core Dump Konrad, Martin

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