Re: [Sbcl-help] Lisp Server Disconnect and Threading Issues

[Brian P. <bperry@MIT.EDU>]

Thanks for the reply Leslie.  I dug a little deeper into what's possible regarding exception handling, and it does seem likely that would allow us to work around / more gracefully handle this error case.

As for the second issue - I'm still relatively new to Lisp, but I'm always willing to learn.  Is there any particular resource you (or others reading) would suggest as a crash course on threading for scbl?

Brian 


On Thursday, May 3, 2012 at 6:07 AM, Leslie P. Polzer wrote:

> 
> Brian Perry wrote:
> > Greetings,
> > 
> > I've been working on adapting existing Lisp code to communicate with a socket server
> > with the end goal of allowing a couple of different web based clients (one using Flash,
> > another in Processing) to communicate with the Lisp server. I've run into a couple of
> > specific roadblocks and was wondering if anyone could help.
> > 
> > The first issue is that the lisp server is crashing when a client disconnects. I'm
> > seeing an error similar to the following:
> > 
> > -------
> > debugger invoked on a END-OF-FILE in thread #<THREAD RUNNING {1003707001}>:
> > end of file on #<SB-SYS:FD-STREAM for "a socket" {10037EFDE1}>
> > 
> 
> 
> You want to catch that exception, or check for end of file before you read,
> or disable the condition throw on EOF (if possible).
> 
> 
> > The second issue is that the Lisp server currently blocks when one connection is made,
> > preventing other clients from connecting simultaneously. I've assumed that sbcl's
> > threading might help here, but I didn't have any luck with it myself (most likely due to
> > lack of experience).
> > 
> 
> 
> I haven't looked at your code, but I suppose some kind of non-blocking
> or event-based I/O might be possible. On the other hand it might still
> be easier to get used to threads since it's not that hard...
> 
> Leslie
> 
> 
> > 
> > I based the server on the following example:
> > 
> > http://jsnell.iki.fi/tmp/echo-server.lisp
> > 
> > I'd be happy to provide more info if it helps.
> > 
> > Thanks,
> > 
> > Brian
> > 
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> 
> 
> 
> --