Package: libc6 Version: 2.7-5 Severity: normal
In my multithreaded application I'm finding calls to pthread_cond_wait are occasionally not woken by pthread_cond_broadcast. Some possibly relevent factors: * This is a single CPU, single core box * There's typically 1-3 threads calling pthread_cond_wait * There's a single global cond used, but each thread has their own lock * A maintenance thread (although the roles change) acquires all of the threads' locks, ensuring they're all asleep. It then calls pthread_cond_broadcast, followed by releasing all their locks * The maintanance thread does this repeatedly, successfully waking up other threads from the cond, as well as repeatedly acquiring and releasing the hung thread's lock * I've verified with my own logging and strace that the maintenance thread is acquiring the same lock passed to pthread_cond_wait by the hung thread * A snippet from strace's log (full size 43 megs): http://pastebin.com/f41c0c791 * I've verified with gdb that the hung thread is in "#0 0xb7edf820 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/libpthread.so.0" * Attaching and detaching gdb causes the hung thread to wakeup and finish normally. I was told of a patch on IRC, but I was later told it did not affect x86 (which I'm using). For posterity, here's what I had written: Additionally, I was told on IRC of a patch set to glibc's locking code that came out after 2.7. I haven't verified if these would fix it, or if they're even related, but it's something to consider. http://sources.redhat.com/bugzilla/show_bug.cgi?id=5240 Three changed files are linked there. I was given a 4th on IRC, which I'm told is a correction. http://sourceware.org/cgi-bin/cvsweb.cgi/libc/nptl/sysdeps/unix/sysv/linux/lowlevellock.c.diff?cvsroot=glibc&r1=1.18&r2=1.19 -- System Information: Debian Release: lenny/sid APT prefers unstable APT policy: (500, 'unstable'), (500, 'testing'), (1, 'experimental') Architecture: i386 (i686) Kernel: Linux 2.6.22-2-k7 (SMP w/1 CPU core) Locale: LANG=en_CA.UTF-8, LC_CTYPE=en_CA.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/bash Versions of packages libc6 depends on: ii libgcc1 1:4.2.2-1 GCC support library libc6 recommends no packages. -- debconf information excluded -- Adam Olsen, aka Rhamphoryncus -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
