0004844: Unix.select bug (triggered if linked against threads) - MantisBT

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ID

Project

Category

View Status

Date Submitted

Last Update

0004844

OCaml

OCaml general

public

2009-08-07 12:51

2012-03-24 15:01

Reporter

Christoph Bauer

Assigned To

gildor

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS

OS Version

Product Version

3.11.0

Target Version

Fixed in Version

3.12.0+dev

Summary

0004844: Unix.select bug (triggered if linked against threads)

Description

The attached program fails, if compiled with
ocamlopt -thread -o selectbug.exe unix.cmxa threads.cmxa selectbug.ml
and runs, if compiled with
ocamlopt -thread -o selectbug.exe unix.cmxa selectbug.ml

If you run it, please type some input, because it makes a Unix.select on stdin.

Additional Information

There was a discussion on the mailing (8-July-2009) list about the problem.

Tags

No tags attached.

selectbug.ml [^] (522 bytes) 2009-08-07 12:51

select.c [^] (29,650 bytes) 2009-08-10 10:18

Relationships

Notes
(0005041) gildor (developer) 2009-08-07 13:28	Discussion is here http://groups.google.com/group/fa.caml/browse_thread/thread/c634c736765897ee# [^] Possible problem/solution: I use "lpOrig = (void )fd;" where fd is an OCaml value (in select.c). Without thread and during the enter/leave_blocking_section(), there is less chance to trigger the GC and to modify "fd" value. This is the reason why it seems correct without thread and fall into a bug with thread. The obvious solution is to replace "lpOrig = (void )fd" by a non-OCaml value (e.g. EMode + nth in ocaml list).

(0005042) Christoph Bauer (reporter) 2009-08-10 10:17	The hinted solution seems to work. I'll attach a modified version of otherlibs/win32unix/select.c, which solved the problems in selectbug.ml and my original program. But beware, I haven't it tested very well.

(0005219) Christoph Bauer (reporter) 2010-01-07 10:16	I use this patch (select.c) every day - and it works. So now I could say, it's well tested.

(0005506) gildor (developer) 2010-05-25 15:21	Apply patch by C. Bauer, replace lpOrig by lpOrigIdx which can survive a GC collection

Issue History
Date Modified	Username	Field	Change
2009-08-07 12:51	Christoph Bauer	New Issue
2009-08-07 12:51	Christoph Bauer	File Added: selectbug.ml
2009-08-07 13:28	gildor	Note Added: 0005041
2009-08-10 10:17	Christoph Bauer	Note Added: 0005042
2009-08-10 10:18	Christoph Bauer	File Added: select.c
2010-01-07 10:16	Christoph Bauer	Note Added: 0005219
2010-01-07 15:17	doligez	Status	new => acknowledged
2010-04-18 20:35	xleroy	Status	acknowledged => assigned
2010-04-18 20:35	xleroy	Assigned To	=> gildor
2010-05-20 10:47	gildor	Status	assigned => confirmed
2010-05-25 15:21	gildor	Note Added: 0005506
2010-05-25 15:21	gildor	Status	confirmed => resolved
2010-05-25 15:21	gildor	Fixed in Version	=> 3.12.0+dev
2010-05-25 15:21	gildor	Resolution	open => fixed
2012-03-24 15:01	xleroy	Status	resolved => closed

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