[PD] Externals with threads ...

Tim Blechmann TimBlechmann at gmx.net
Tue Jan 25 09:11:43 CET 2005

> I'm wondering what peoples opinions are on the subject of externals
> with their own threads. Are there reasons this is is not advised (e.g.
> reentrancy of subsequent calls)? To be specific I'm talking about
> threads that initiate output. I've looked at the sourcecode for
> netreceive and noticed the use of sys_addpollfn, but as this method is
> not included in m_pd.h, i wonder if it's even intended to be used in
> externals. One of the reasons i ask is that the example/test code
> attached bellow seems to work on one of my machines (Pentium 4/Fedora
> 2/PD 0.37.1), but when I run it on another (a PowerbookG4/Gentoo/PD
> 37.4) I get a stack overflow at the outlet_float. 
well ... the only threadsafe way to synchronize helper threads with the
main pd thread is to place callbacks in the scheduler.
afaik the only externals using them are flext and join.
still, the |read( message to the threaded soundfiler should give you an
idea, how threadsafe external programming can be done. (recent

problem: the possibility to place callback in the scheduler is NOT
implemented in any stable release. still, i hope it will make it's way
to 0.39...

cheers ... tim

mailto:TimBlechmann at gmx.de    ICQ: 96771783

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