From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Drouin Subject: linux and pthread Date: Wed, 10 Nov 2004 15:02:36 -0500 Message-ID: <419273DC.3050208@bic.mni.mcgill.ca> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: linux-c-programming-owner@vger.kernel.org List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Linux c programming list Hi all, Not sure it is the best place to post that. Tell me if you have any other suggestion. I'm running Mandrake 10 and developping a C/C++ program using multiple threads. My program has a main thread that manages UI and a second thread is in a loop that continuously grabs data from a serial port. The communication between the 2 threads is controled by a mutex. The grabbing thread holds the mutex for most of the time in its loop. My problem is that when the main thread tries to lock the mutex, it is suspended forever, like if the grabbing thread didn't release the mutex lock for long enough for the main thread to lock it. The FAQ on the LinuxThreads page says that it used to be a problem with versions < 0.8 of LinuxThreads. In versions 0.8 and later, a thread that locked a mutex while another one was holding it was sure to be scheduled as soon as the other thread released the mutex. And I suppose Mandrake 10 has a version >= 0.8 since the faq was pretty old. Now, I've been trying to figure out which version of LinuxThread I was using. Here's the output of find / -name 'libpthread*.so*': /usr/lib/libpthread.so /usr/lib/valgrind/libpthread.so /usr/lib/valgrind/libpthread.so.0 /lib/i686/libpthread-0.10.so /lib/i686/libpthread.so.0 /lib/tls/libpthread-0.10.so /lib/tls/libpthread.so.0 /lib/libpthread-0.10.so /lib/libpthread.so.0 When I do a 'ldd' on my program, I can see it is using /lib/tls/libpthread.so.0. Is there a documentation somewhere on what is what in this list. Seems like there are 2 versions of libpthread out there: the original LinuxThreads lib and the "Native Posix Thread Library"(nptl) (correct me if I'm wrong). Some forum I ran into suggests that what is in /lib/tls is related to nptl. Is it the case? If so, what are all the others? Are they all different builds of LinuxThreads? ld seems to be falling back on /lib/i686/libpthread.so.0 if I rename the /lib/tls directory. If I run my program with /lib/i686/libpthread.so.0, my schedulling problem seems to disapeer. Is there any known bugs in nptl and if so, where can I get the information? Thanks in advance. Simon Drouin