Experimental Physics and
Industrial Control System

All,

I created Mantis entry 343 to track this issue.

Sorry about the slow response, I was out for a few days due to catching the
flu.

Jeff

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]
> On Behalf Of Dirk Zimoch
> Sent: Tuesday, June 23, 2009 2:00 AM
> To: [email protected]
> Cc: [email protected]
> Subject: Re: sigsev while creating new gdd in multiple threads
> 
> Hi Bruno,
> 
>  From what I can see in the macro definition of gdd_NEWDEL_NEW(gdd) in
> gddNewDel.h, the gddScalar::new() operator is not fully thread safe.
> Initialization of the freelist is not protected. Thus, calling gdd*::new()
> for
> the first time in two different threads may crash. Maybe using gdd*::new()
> the
> first time while still in single threaded context may cure the problem.
> 
> Dirk
> 
> 
> Bruno Coudoin wrote:
> > Hi,
> >
> > Tonight I found something odd. I am perhaps doing something wrong but
> > after several test the results were consistant.
> >
> > I have a multithreaded application, at startup each thread creates
> > several gdd. It ends up frequently in the following SIGSEGV:
> >   Program received signal SIGSEGV, Segmentation fault.
> >   [Switching to Thread 0x98a35b90 (LWP 1020)]
> >   0x00f2b2b8 in gdd::operator new (size=44) at ../gdd.cc:26
> >   26      gdd_NEWDEL_NEW(gdd)
> >
> > My code to create the gdd is as simple as:
> >   gdd *pDD;
> >   pDD = new gddScalar ( gddAppType_value, aitEnumInt32 );
> >
> > It seems like my program crashes at startup but if it passed the first
> > gdd creation of each threads, it becomes stable after that. More threads
> > I have, more chance I have to see the crash.
> >
> > My configuration:
> > Epics 3.14.10
> > CentOS 5.3
> > Multi core processor.
> >
> > Has anybody ever seen this issue? I'll try to dig further tomorrow, if
> > someone has ideas on workarounds or tests to do to refine the issue,
> > your welcome.
> >
> > Bruno.
> >
> >
> >
> 
> --
> Dr. Dirk Zimoch
> Paul Scherrer Institut, WBGB/006
> 5232 Villigen PSI, Switzerland
> Phone +41 56 310 5182

Replies:

RE: sigsev while creating new gdd in multiple threads Bruno Coudoin

References:

sigsev while creating new gdd in multiple threads Bruno Coudoin

Re: sigsev while creating new gdd in multiple threads Dirk Zimoch

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