[Gc] Ignoring registered threads?

Julian Hall jules at meridiandigital.co.uk
Thu Jun 29 07:05:24 PDT 2006

I've been looking through the archives and can't find anything much 
about this, but I'm working on an application which has a number of 
soft-real-time threads that I would ideally like to avoid being 
interrupted for a stop-the-world collection (it's a multimedia 
application working with small buffers to minimise latency, and a longer 
than average world stop could easily cause jittering).  My current 
design has these threads doing some dynamic object allocation at 
start-up time, so I can't really prevent them being registered by using 
"#undef CreateThread".  Working around this would involve creating 
additional threads, which I'm keen to avoid.

The only reference I've found to this kind of behaviour is a message 
from 2003 (archive at 
) in which Hans said:

> You might rarely want to do that to avoid stopping
> it during GC.  But this imposes severe constraints on what that thread 
> can do.
> In particular, it can't write any pointers to the collected heap, or 
> allocate
> memory using the GC_ routines.

After startup has completed, I will be able to make those guarantees.  
Are there any other requirements on the thread's behaviour that I should 
be aware of?

He goes on to propose a 'GC_ignore_thread()' API that would allow this 
to be done.  Has this been implemented?  I see it isn't in version 6.4, 
but would I get it if I upgraded?  If not, is it expected in a 
near-future release?

Thanks for your help


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