[slime-devel] slime has broken cmucl mp

[Helmut Eller]

* Madhu [2008-10-30 18:48+0100] writes:

> It used to be possible to run multiprocessing servers like a webserver
> which coexisted with slime.  This is no longer possible With current CVS
> slime, swank's WAIT-FOR-EVENT blocks all other processes from handling
> FD events

SLIME's WAIT-FOR-STREAMS calls SYS:SERVE-EVENT with a timeout of 0.2
seconds.  That's shorter than LISP::*MAX-EVENT-TO-SEC*--which is 1
second--and consequently the LISP::*PERIODIC-POLLING-FUNCTION* isn't
called.

> There is a simple test case, but here is a more realistic one: I'm
> attaching a program "t2.lisp" which seeks to illustrates the
> problem. This is a simple program which listens on a port [8128 by
> default] and prints a message to clients which connect to it.
>
> -- In a bare lisp 
>
> * (load "t2.lisp")
>
> LISTEN-FOR-CONNECTIONS creates a process which listens at port 8128.
>
> -- run `telnet localhost 8128' from a shell, a few times.
>
> This will result in the bogus service printing a message to the telnet
> client, as expected.
>
> -- load slime in the lisp, and listen at port 4005
>
> * (load "/path/to/swank-loader.lisp")
> * (swank-loader::init)
> * (swank::setup-server 4005 #'print nil nil (swank::find-external-format "latin-1-unix"))
>

nil as *communication-style* is not the default.

> -- Connect to the lisp from emacs using M-x slime-connect localhost 4005
>
> -- run `telnet localhost 8128' from a shell.
>
> This hangs until the slime connection exits.

It doesn't hang in the default configuration.

More precisely, it doesn't hang if I run SLIME with 
(eq *communication-style* :sigio).  
It hangs, with the default config, if the SLIME debugger is active.

It doesn't hang, even with active debugger, if 
(eq *communication-style* :spawn).

It doesn't hang, even with active debugger, if *max-event-to-sec* is 0
and *max-event-to-usec* is 1000.

It doesn't hang, even with active debugger, with
(eq *communication-style* :sigio) if multiprocessing is
initialized properly and the idle process runs.  E.g. if you start the
swank server with:

  (swank::initialize-multiprocessing (lambda () (swank:create-server)))

> This is a serious problem, and exposes many issues with SLIME's design.
 
Which issues?

Helmut.