guile and pthreads again

* guile and pthreads again
@ 2004-04-21 21:16 Julian Graham
  2004-05-17 21:05 ` Marius Vollmer
  0 siblings, 1 reply; 2+ messages in thread
From: Julian Graham @ 2004-04-21 21:16 UTC (permalink / raw)

Hi everyone,
  I know this has been addressed several times before, but I haven't been 
able to find a satisfactory explanation in the docs, mailing list, or 
newsgroups.  I'm using Guile 1.6.4 as an embedded interpreter of user code 
in a multithreaded (via pthreads) server program I'm writing.  I understand 
that in order to portably examine the stack, Guile must be launched in a 
stack frame below the ones in which it is used.  Will this work in my 
program, in which I am routinely starting new threads as users connect?  It 
seems like there have been some problems in previous versions that have 
since been resolved, possibly via the introduction of the scm_spawn_thread 
function.

  I'm a little leary of using it, however, since a) there's no documentation 
for it as far as I can tell (in general I have a hard time telling whether 
the documentation is talking about OS threads or Scheme threads); and b) it 
takes Guile-defined types as arguments and returns a SCM.  For what it's 
worth, I'm not interested (as yet) in threads of Scheme code being launched 
by Scheme or C code, only in multiple threads of my C code being able to 
call functions in Guile's C API.  It would be okay if I had to lock some 
kind of Guile mutex in order do this.  It would even be okay if each thread 
had to have its own Guile 'instance', since I'd like to have them evaluate 
expressions pretty much in isolation from each other.

  Finally, provided scm_spawn_thread or some other pthread-replacing code is 
necessary, how will this play with regular pthread operations, such as 
joining and cancelling?  Will the cancel function for a Guile-aware thread 
also be Guile-aware so that it can, for example, unprotect a previously 
GC-protected object?  Will the garbage collector then be able to free such 
memory once the cancel function exits and the thread has been destroyed?  Is 
there a more comprehensive set of documentation, in CVS, maybe, that makes 
this clearer?

  Apologies if any of this is covered in some obviously place...

Thanks in advance,
Julian

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