0000022: Scheduling problem with Posix threads

View Issue Details [ Jump to Notes ]

[ Issue History ] [ Print ]

Project

Category

View Status

Date Submitted

Last Update

0000022

OCaml

OCaml general

public

2000-01-13 10:50

2006-06-17 11:54

Reporter

administrator

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

fixed

Platform

OS Version

Product Version

Target Version

Fixed in Version

Summary

0000022: Scheduling problem with Posix threads

Description

Full_Name: Jerome Vouillon
Version:
OS:
Submission from: estephe.inria.fr (128.93.11.95)
Submitted by: xleroy

Dans l'exemple suivant, le programme utilisant les threads est
complètement bloqué par celui ne les utilisant pas...

-- Jérôme

mistral-jerome:~/tmp > cat > essai.ml
let _ = let x = ref 0. in for i = 0 to 10000000 do x := !x *. 1.1 done
mistral-jerome:~/tmp > ocamlc -o essai essai.ml
mistral-jerome:~/tmp > cat essai2.ml
let _ = Thread.create
let _ = let x = ref 0. in for i = 0 to 10000000 do x := !x *. 1.1 done
mistral-jerome:~/tmp > ocamlc -custom -thread -o essai2 unix.cma \
threads.cma essai2.ml -cclib "-lunix -lthreads -lpthread"
mistral-jerome:~/tmp > time ./essai & time ./essai2
[1] 1292
./essai 13,21s user 0,01s system 98% cpu 13,470 total
[1] + done time ./essai
./essai2 12,97s user 0,02s system 49% cpu 26,415 total

[Damien Doligez:]
Pas reproductible sur Tru64. Feature de Linux Threads ?

[Jerome Vouillon:]
Voilà ce qui se passe :
Il y a un thread qui signale toutes les 50ms au thread s'exécutant à
ce moment là de laisser la place à un autre thread. Ce thread appelle
pour celà sched_yield. Comme il y a un autre processus qui peut
s'exécuter le thread ne reprend la main qu'après plus de 50ms... et
rappelle immédiatement sched_yield, car le thread horloge s'est
exécuté entre temps. Le thread principal n'a donc jamais l'occasion de
s'exécuter.

-- Jérôme

Tags

No tags attached.

Attached Files

Relationships

Notes
(0003067) administrator (administrator) 2004-06-25 17:40	May be related to PR#2663 and PR#2714

(0003690) xleroy (administrator) 2006-06-17 11:54	Starting with 3.08, the thread library does more careful use of sched_yield(). The example given works OK in 3.09 under Linux 2.6.

Issue History
Date Modified	Username	Field	Change
2005-11-18 10:14	administrator	New Issue
2006-06-17 11:54	xleroy	Note Added: 0003690
2006-06-17 11:54	xleroy	Status	acknowledged => closed
2006-06-17 11:54	xleroy	Resolution	unable to reproduce => fixed
2006-06-17 11:54	xleroy	Description Updated