perl4caml crashed with threads

perl4caml crashed with threads

[xuzq]

Hi,

On my debian sid box,the following prog core dump.What's wrong?Is it
all right on your machine or is it a bug?

open Printf
open Perl

let test ()=
 try
 let sv=Perl.eval "3+7" in
 let r=int_of_sv sv in
   printf "result=%i" r
 with _->printf "error"

let ()=Thread.join (Thread.create test ())

The command line:
ocamlc -thread -I +perl /usr/lib/perl/5.8/auto/DynaLoader/DynaLoader.a
perl4caml.cma unix.cma threads.cma test.ml -o test
Version:
Ocaml          3.08.3 & 3.09.0
perl4caml   0.9.3

regards.

Re: [Caml-list] perl4caml crashed with threads

[Richard Jones]

On Mon, Nov 14, 2005 at 02:16:43AM +0000, xuzq wrote:
> On my debian sid box,the following prog core dump.What's wrong?Is it
> all right on your machine or is it a bug?

This crashes on my machine too.  However if you remove all references
to threads, then it works.  libperl and perl4caml don't make any
attempt to be thread-safe.

Rich.

-- 
Richard Jones, CTO Merjis Ltd.
Merjis - web marketing and technology - http://merjis.com
Team Notepad - intranets and extranets for business - http://team-notepad.com

Re: [Caml-list] perl4caml crashed with threads

[Florian Weimer]

* Richard Jones:

> On Mon, Nov 14, 2005 at 02:16:43AM +0000, xuzq wrote:
>> On my debian sid box,the following prog core dump.What's wrong?Is it
>> all right on your machine or is it a bug?
>
> This crashes on my machine too.  However if you remove all references
> to threads, then it works.  libperl and perl4caml don't make any
> attempt to be thread-safe.

Debian's libperl does (it's compiled for thread safety), so perl4caml
is the likely culprit.

Re: perl4caml crashed with threads

[xuzq]

Richard Jones <rich <at> annexia.org> writes:

> 
> On Mon, Nov 14, 2005 at 02:16:43AM +0000, xuzq wrote:
> > On my debian sid box,the following prog core dump.What's wrong?Is it
> > all right on your machine or is it a bug?
> 
> This crashes on my machine too.  However if you remove all references
> to threads, then it works.  libperl and perl4caml don't make any
> attempt to be thread-safe.
> 
> Rich.
> 
Yes,it 's ok without threads and i see perl4caml may not be thread-safe.I 'm
only curious about why only "eval" crashes and "call" looks fine.In my program
another thread run the following code without any error.

    let (sv_dbf_sz,sv_dbf_sh)=(call_class_method "CAM::DBF" "new" [sv_of_string
path_sz],call_class_method "CAM::DBF" "new" [sv_of_string path_sh]) in
    let (rn_sz,rn_sh)=(int_of_sv (call_method sv_dbf_sz "nrecords" []),int_of_sv
(call_method sv_dbf_sh "nrecords" [])) in
      for i=0 to rn_sz-1 do 
	let row = call_method_array sv_dbf_sz "fetchrow_array" [sv_of_int i] in 
	  match row with
...	    

Thank you for your excellent perl4caml,Richard!Would it be possible for perl
to callocaml code just like the Inline::OCaml thoughts in that post:
http://caml.inria.fr/pub/ml-archives/caml-list/2002/02/
e363d76f1e9b94779b1ffe7de3a7c011.en.html?

Re: [Caml-list] Re: perl4caml crashed with threads

[Richard Jones]

On Tue, Nov 15, 2005 at 02:03:20AM +0000, xuzq wrote:
> Yes,it 's ok without threads and i see perl4caml may not be
> thread-safe.I 'm only curious about why only "eval" crashes and
> "call" looks fine.In my program another thread run the following
> code without any error.

I'm guessing that 'call' works by luck.

I had a quick scan of the code and I can't see anything obviously
unsafe.  Since I never release the OCaml lock in any of the C code,
surely the C calls are all serialised?  It might also be that
perl4caml_init is being called twice (from two threads) which would
probably cause bad things to happen.  A simple print statement should
diagnose whether this is the case.

To be honest, I'm not sure what the threading issues are when calling
external C libraries.  I rarely even use threading in OCaml, and as
you probably guessed, I've never used it at all from perl4caml.

> Thank you for your excellent perl4caml,Richard!Would it be possible for perl
> to callocaml code just like the Inline::OCaml thoughts in that post:
> http://caml.inria.fr/pub/ml-archives/caml-list/2002/02/e363d76f1e9b94779b1ffe7de3a7c011.en.html?

Inline::OCaml would certainly be nice to have, but I don't have the
time, or possibly even the skills, to write it.

Rich.

-- 
Richard Jones, CTO Merjis Ltd.
Merjis - web marketing and technology - http://merjis.com
Team Notepad - intranets and extranets for business - http://team-notepad.com