Date: Thu, 23 Nov 2006 18:48:17 +0200 (EET) From: Andriy Gapon <avg@icyb.net.ua> To: FreeBSD-gnats-submit@FreeBSD.org Cc: sem@FreeBSD.org Subject: ports/105794: devel/ace: can not create more than ncpu threads with default thread flags Message-ID: <200611231648.kANGmHNl027945@oddity.topspin.kiev.ua> Resent-Message-ID: <200611231650.kANGoIuL013644@freefall.freebsd.org>
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>Number: 105794
>Category: ports
>Synopsis: devel/ace: can not create more than ncpu threads with default thread flags
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-ports-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Nov 23 16:50:16 GMT 2006
>Closed-Date:
>Last-Modified:
>Originator: Andriy Gapon
>Release: FreeBSD 6.1-RELEASE-p2 i386
>Organization:
>Environment:
System:
FreeBSD 6.1-RELEASE-p2 i386
ace-5.5.1
libpthread is used as threads lib
>Description:
Please see the attached program.
It fails with the following output:
spawning thread #0
spawned thread #0 (thr_id=8053400)
spawning thread #1
spawn failure: Resource temporarily unavailable
Exit 71
ktrace shows the following information:
27360 thread GIO fd 2 wrote 19 bytes
"spawning thread #1
"
27360 thread RET write 19/0x13
27360 thread CALL kse_create(0x804bf0c,0)
27360 thread RET kse_create -1 errno 67 Too many processes
It seems that the problem occurs because flag THR_NEW_LWP, included into default set of ACE thread flags,
is interpreted by ACE library as an instruction to call pthread_setconcurrency with concurrency level
set to current number of threads created through ACE. FreeBSD libpthread refuses to set
concurrency higher than a number of CPUs available. ACE library treats pthread_setconcurrency() failure
as a fatal failure for thread creation.
Any solution for this problem should probably be submitted to ACE maintainers for
inclusion into ACE platform-specific source base.
>How-To-Repeat:
1. Change the attached program so that thr_num variable is greater than the number of CPUs on your test machine.
2. Compile the attached program:
$ c++ thread.cpp -o thread -I /usr/local/include -L /usr/local/lib -lACE -pthread
3. Make sure that libpthread is used as your thread support library:
$ ldd thread
thread:
libACE.so.5 => /usr/local/lib/libACE.so.5 (0x48077000)
libstdc++.so.5 => /usr/lib/libstdc++.so.5 (0x48196000)
libm.so.4 => /lib/libm.so.4 (0x4826c000)
libpthread.so.2 => /usr/lib/libpthread.so.2 (0x48283000)
libc.so.6 => /lib/libc.so.6 (0x482aa000)
4. run the program
>Fix:
Workaround: use libthr as a threading library
Solution 1: change a meaning of THR_NEW_LWP on FreeBSD as term "LWP" is not directly
applicable to FreeBSD threading model. Reasonable approach is to alias THR_NEW_LWP
to THR_SCOPE_SYSTEM.
Solutuion 2: do not treat failure of pthread_setconcurrency() as a fatal error
for thread creation.
No patches, sorry.
--- thread.cpp begins here ---
#include <sysexits.h>
#include <ace/Log_Msg.h>
#include <ace/Thread.h>
#include <ace/Thread_Manager.h>
ACE_THR_FUNC_RETURN thr_func(void*)
{
ACE_DEBUG((LM_DEBUG, ACE_TEXT("in thr_func\n")));
ACE_OS::sleep(1);
ACE_DEBUG((LM_DEBUG, ACE_TEXT("out thr_func\n")));
return 0;
}
int ACE_TMAIN(int /*argc*/, ACE_TCHAR* /*argv*/[])
{
ACE_TRACE(ACE_TEXT("main\n"));
const int thr_num = 2;
ACE_thread_t t_id[thr_num];
for (int i = 0; i < thr_num; ++i) {
ACE_DEBUG((LM_DEBUG, ACE_TEXT("spawning thread #%d\n"), i));
if (ACE_Thread::spawn(thr_func, 0, THR_NEW_LWP | THR_JOINABLE | THR_INHERIT_SCHED, &t_id[i]) == -1) {
ACE_ERROR_RETURN((LM_ERROR, ACE_TEXT("spawn failure: %m\n")), EX_OSERR);
}
ACE_DEBUG((LM_DEBUG, ACE_TEXT("spawned thread #%d (thr_id=%X)\n"), i, reinterpret_cast<unsigned long>(t_id[i])));
}
for (int i = 0; i < thr_num; ++i) {
ACE_DEBUG((LM_DEBUG, ACE_TEXT("joining thread #%d\n"), i));
ACE_Thread::join(t_id[i], 0, 0);
ACE_DEBUG((LM_DEBUG, ACE_TEXT("joined thread #%d\n"), i));
}
return 0;
}
--- thread.cpp ends here ---
>Release-Note:
>Audit-Trail:
>Unformatted:
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