[Gc] Incremental collection in gcj?

Boehm, Hans hans.boehm at hp.com
Thu May 26 17:20:51 PDT 2005


I suspect the problem here is an old bug, and a patch that never made it
into the 3.4 branch.  If you want to fix it, the patch was applied in
version
1.2 of pthread_stop_world.c in the gcc tree on savannah.gnu.org.

4.0 should not have this particular problem, since it uses version 1.3
of
that file.

Incremental/generational gc is not supported in gcj, though you
might be able to get it to work.  I don't think anyone has ever
gone through and made sure that no system calls in libgcj write into
pointer-containing heap objects.  If they do, those system calls may
fail, since incremental GC write-protects heap pages.  Unlike
store instructions, system calls are not always transparently restarted
after unprotecting the page.

Hans

> -----Original Message-----
> From: gc-bounces at napali.hpl.hp.com 
> [mailto:gc-bounces at napali.hpl.hp.com] On Behalf Of kus Kusche Klaus
> Sent: Wednesday, May 25, 2005 6:15 AM
> To: gc at napali.hpl.hp.com
> Subject: [Gc] Incremental collection in gcj?
> 
> 
> I tried to run a gcj-compiled program with incremental gc.
> It failed with a SIGSEGV in GC_restart_handler,
> executed in a signal handling context within a sigsuspend.
> 
> Without GC_ENABLE_INCREMENTAL, the same program works fine.
> 
> My platform is Linux, i686, posix threads, gcc 3.4.3.
> 
> What's the state of incremental boehm gc for gcj?
> I was unable to find a definite word about it.
> Is it expected to work?
> Is it a known bug being worked on?
> Doesn't it work by design?
> Any hope for the future?
> 
> Are there any other incremental / generational gc's for gcj
> (to reduce non-responsive times due to gc)?
> 
> Please reply directly, I'm not subscribed.
> 
> Thanks!
> 
> -- 
> Klaus Kusche
> Entwicklung Software - Steuerung
> Software Development - Control
> 
> KEBA AG
> A-4041 Linz
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> Tel +43 / 732 / 7090-3120
> Fax +43 / 732 / 7090-6301
> E-Mail: kus at keba.com
> www.keba.com
> 
> 
> 
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