threads/80887: ULE with SMP broke libpthread/libthr on 5.4-RELEASE

Steven Jurczyk steve at
Wed May 11 04:50:03 PDT 2005

>Number:         80887
>Category:       threads
>Synopsis:       ULE with SMP broke libpthread/libthr on 5.4-RELEASE
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-threads
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed May 11 11:50:02 GMT 2005
>Originator:     Steven Jurczyk
>Release:        5.4-RELEASE
FreeBSD 5.4-RELEASE FreeBSD 5.4-RELEASE #17: Wed May 11 11:11:01 CEST 2005     steve at  i386

Using ULE on SMP machine broke applications which use libpthread/libthr, probably at context switching between threads... The applications simply hang and they aren't killable (kill -9 <pid> don't work).. Usually this also break kernel shutdown (can't flush some inodes or blocks)...

Compile kernel with options:

options SMP
options SCHED_ULE

and try to start mysqld_server on dual dual processor (may be on Pentium IV with enabled HT)

The problem also is repeatable at 50% success rate with simple /usr/bin/host util. 

Setting setenv LIBPTHREAD_SYSTEM_SCOPE usually helps to hang any pthreads application at their initialization.

sorry :)

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