[Gc] Crashs and Deadlocks in the GC on windows-xp

Boehm, Hans hans.boehm at hp.com
Tue Mar 14 13:21:25 PST 2006

Any chance we could include your stress test in the GC distribution?

GC7 tries to clean up a lot of this, and more thorough tests would be

Can you get stack traces corresponding to the deadlocks?  Those don't
sound familiar at all.

The Dll magic has been a source of problems in the past.  Gc7 uses the
other approach by default.


> -----Original Message-----
> From: gc-bounces at napali.hpl.hp.com 
> [mailto:gc-bounces at napali.hpl.hp.com] On Behalf Of Lothar Scholz
> Sent: Monday, March 13, 2006 11:53 PM
> To: gc at napali.hpl.hp.com
> Subject: [Gc] Crashs and Deadlocks in the GC on windows-xp
> Hello,
> I just spend this morning to write a multithreading, garbage 
> collector stress test program and found two serious problems.
> First, after a few seconds of thread creation and destruction 
> i always run into an error that GC_stop_world calls 
> SuspendThread on an invalid handle. The windows 
> GetLastError() code is 6. This happens with 6.6 and 6.7 and 
> is very repeatable for me. First i tried to catch this 
> situation and simply close the handle in the thread table 
> when such a situation came up but this did not help very much.
> Also the comment above in the function told me that i'm not 
> the first one who had this problem.
> So i solved it by using GC_CreateThread and linking to a 
> static compiled library instead of using the DLL magic. I 
> never had invalid handles anymore.
> But there is still one problem left: It looks like i run into 
> a deadlocks after some time. But it maybe something different 
> as my dual processor is having a 50% CPU load. Is there any 
> spinlock blocking that might cause this behaviour ? Is 
> anybody out there who also saw this in the past ?
> At the moment, i'm 75% convinced that it is a GC bug.
> --
> Best regards,
>  Lothar Scholz              mailto:scholz at scriptolutions.com
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