Re: thread safe?

I will provide a small sample as soon as I can get to it but here is a 
bit more information. I'm using PLT version 205 (Kiril's port of SSAX). 
I'm using the PLT-specific thread library which is pretty solid; the 
production system works as a socket-based client/server with the PLT 
system acting as an XML processor listening on a socket; a connect from 
the data source spawns a new socket which is then passed to a new thread 
having it's own input/output ports. This thread uses SSAX:make-parser to 
do the work.

I'm fairly convinced that it is pilot error at this point but I've tried 
to reduce my code footprint to a minimum and I still see the problem.

I'm not sure how the threads could not have their own distinct input (or 
output) ports given this scenario but I will explore that possibility 
further.

Thanks for replying; I'm going to try to put that example together for 
you later today.

[email protected] wrote:
> Hello!
> 
> 
>>I'm wondering if there are any obvious pitfalls -- first prototype
>>doesn't look good (seeds getting stomped on, etc.),
> 
> 
> One has to be careful with the input port. The port is considered as a
> linearly updateable datum. So, two different instances of SSAX in two
> different threads must have their own, separately created, input port
> (even both ports eventually refer to the same file). We also should
> make sure that just reading from ports is thread-safe. As I recall, it
> is safe on Gambit. Of course it depends what kind of thread system we
> deal with: implemented by a particular Scheme system or POSIX
> threads. In the latter case, we should make sure that the whole i/o
> library (libc) is thread-safe and the Scheme run-time is compiled with
> thread-safe system libraries.
> 
> The seeds in SSAX are treated _explicitly_ as linear parameters -- this
> is as thread-safe as one can possibly get. 
> 
> If it is possible to provide some details (or a small representative
> example), it would help to analyze the problem further.
> 
> 	Cheers,
> 	Oleg


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