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User-Agent: Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)


The Apache server produces segmentation violation when using
module that uses POSIX threads. 

Reproducible: Sometimes
Steps to Reproduce:
1.Compile an Apache module that links with POSIX Threads
  There is a very small module that illustrates this at
  http://ftp.indexdata.dk/pub/mod_thr.tar.gz
2.Install it
3.Start Apache

Actual Results:  This is what happens when loading module mod_thr.so that
is linked with pthreads:

[root@gamma mod_thr]# /etc/rc.d/init.d/httpd start
Starting httpd:                                            [FAILED]
[root@gamma mod_thr]# gdb /usr/sbin/httpd 
GNU gdb 5.0
Copyright 2000 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you 
are
welcome to change it and/or distribute copies of it under certain 
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux"...
(no debugging symbols found)...
(gdb) run -X -f /etc/httpd/conf/httpd.conf
Starting program: /usr/sbin/httpd -X -f /etc/httpd/conf/httpd.conf
[New Thread 1024 (LWP 5937)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1024 (LWP 5937)]
__res_state () at errno.c:38
38	errno.c: No such file or directory.
	in errno.c
(gdb) bt
#0  __res_state () at errno.c:38
#1  0x401dbd1f in gethostbyname (name=0xbffff518 "gamma.indexdata.dk")
    at ../nss/getXXbyYY.c:108
#2  0x08066ad3 in ap_get_local_host () at eval.c:41
#3  0x08063e7d in ap_fini_vhost_config () at eval.c:41
#4  0x08055372 in ap_read_config () at eval.c:41
#5  0x0805d9bb in main () at eval.c:41
#6  0x40108f11 in __libc_start_main (main=0x805d740 <main>, argc=4, 
    ubp_av=0xbffffaac, init=0x804f1c8 <_init>, fini=0x807e3bc <_fini>, 
    rtld_fini=0x4000e214 <_dl_fini>, stack_end=0xbffffaa4)
    at ../sysdeps/generic/libc-start.c:129


Expected Results:  It works fine when mod_thr.so is not linked with 
pthreads:
[root@gamma mod_thr]# /etc/rc.d/init.d/httpd start
Starting httpd:                                            [  OK  ]
[root@gamma mod_thr]# 



A known "repair" is to add -lpthreads for LIBS in Makefile when
building Apache. Some people think this is a bug in 
GNU LIBC (GLIBC maintainer don't think it's a bug in GLIBC).

This bug has been around for a long time. Some people wrote that
it should be fixed in LIBC 2.2, but it's not fixed LIBC 2.2.1 that
comes with Fisher.

The problem affects all modules that relies on POSIX threads
such as Oracle, some PHP extensions, etc.. Redhat Fisher Tcl
(tcl-8.3.2-50) is also linked with POSIX threads, so Apache
extensions using Tcl no longer work...