id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	difficulty
285	termite hangs and doesn't return values when it should	Jeronimo Pellegrini	Christian Kellermann	"Hello,

It seems that the termite egg -- it looks like processes
don't react to messages immediately -- ""?"" seems to hang
and wait forever.

Below I compare the termite egg with Chicken from git/master (0cc55fe1d91af124b64644ea7fd9a82cd4712e52) to Gambit C 4.6.0 with the termite code from googlecode/svn.

{{{
> (define pid (spawn (lambda () (write (?)))))
> (! pid ""hello world"")
> ""hello world""
}}}
In Chicken:

{{{
#;2> (define pid (spawn (lambda () (write (?)))))
#;3> (! pid ""hello world"")
}}}

Seems like the message got stuck in some buffer...
Something to do with current-output-port, perhaps?

Sometimes I can get an answer:

{{{
#;4> (! pid 'a)
""hello world""
#;5>
}}}

But several times not:

{{{
(...)
#;19> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;20> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;21> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;22> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;23> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;24> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;25> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
#;26> (! pid ""aaaaaaaaaaaaaaaaaaaaaaaaaaa"")
}}}

In Gambit, if I set a timeout for receiving a message and
it actually times out, an exception is raised:

{{{
(? 1)
*** ERROR IN (console)@4.1 -- mailbox receive timed out
(thread-receive 0)
1>
}}}

In Chicken it gets blocked forever:

{{{
#;2> (? 1)
}}}

Hitting ^C gives me a stack trace:

{{{
        Call history:

        termite.scm:103: log-crash
        termite.scm:88: call-with-output-string
        termite.scm:81: continuation-capture
        termite.scm:94: termite-exception?
        termite.scm:103: log-crash
        termite.scm:88: call-with-output-string
        termite.scm:81: continuation-capture
        print-call-chain                        <--
}}}

Defining a value to be returned when ""?"" doesn't get
anything after n seconds also doesn't work:

In Gambit, it returns the value:

{{{
> (? 1 'ok)
ok
>
}}}

In Chicken, it doesn't hang, but no value is returned:

{{{
#;2> (? 1 'ok)
#;3>
}}}

Also, ""on"" seems to hang. On Gambit, I can do this:

Start two gsi interpreters with termite loaded. These
are gambit-A and gambit-B:

{{{
gambit-A> (node-init (make-node ""127.0.0.1"" 3000))
ok


gambit-B> (node-init (make-node ""127.0.0.1"" 3001))
ok
gambit-B> (define A (make-node ""127.0.0.1"" 3000))
gambit-B> (on A (lambda () (print 'x)))
gambit-B>
}}}

B doesn't hang, and ""x"" is written on A's REPL.


On Chicken,

A runs:

{{{
 (use termite)
 (define a (make-node ""127.0.0.1"" 10000))
 (node-init a)
}}}

On B:

{{{
#;2> (node-init (make-node ""127.0.0.1"" 10001))
ok
#;3> (define A (make-node ""127.0.0.1"" 10000))
#;4> (on A (lambda () (print 'x)))
}}}

Nothing is printed on A's REPL, and B hangs.
Again, hitting ^C shows this stach trace:

{{{
        Call history:

        termite.scm:94: termite-exception?
        termite.scm:103: log-crash
        termite.scm:88: call-with-output-string
        termite.scm:81: continuation-capture
        termite.scm:94: termite-exception?
        termite.scm:103: log-crash
        termite.scm:88: call-with-output-string
        print-call-chain                        <--
}}}


It doesn't seem to actually have to do with I/O, because this also
makes B hang:

{{{
#;4> (on A (lambda () (set! x 20) (values)))
}}}

I hope this is just some small issue in the way termite interacts with Chicken's threading code...

Thanks,
J."	defect	closed	major		extensions	4.5.x	wontfix	termite egg