Red Hat Bugzilla – Bug 173915
Can't attach to process with "hand-made" threads
Last modified: 2015-01-07 19:11:14 EST
gdb-6.3.0.0-1.59 When attaching to a process using an old version of the Quadrics library, gdb fails to attach to some "threads": [...] Reading symbols from /lib/tls/libpthread.so.0...Reading symbols from /usr/lib/debug/lib/tls/libpthread-2.3.4.so.debug...done. [Thread debugging using libthread_db enabled] [New Thread 1076535136 (LWP -1)] Error while reading shared library symbols: Can't attach LWP -1: No such process [...] Quadrics creates its "threads" using: if ((res = __clone (elan3_lwp, stack + ELANLWP_STACK_SIZE, CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND, (void *) ctx)) == -1) { elan3_syscall_detach(ctx); return(res); } Whereas the glibc creates a thread using: int clone_flags = (CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGNAL | CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_CHILD_CLEARTID | CLONE_SYSVSEM #if __ASSUME_NO_CLONE_DETACHED == 0 | CLONE_DETACHED #endif | 0);
Your installed "libthread_db.so.1" just needs to be compatible with the thread implementation in the specific application. Please provide the specific version of the Quadrics (libmpi?) binary library, if still relevant. Also RHEL4 provides both linuxthreads (now deprecated) and NPTL threads implementation and it needs to match properly. In fact more important are the specific memory structures created for the threads ("struct pthread"). In each case you could provide your own old-MPI(?) compatible "libthread_db.so.1" implementation, still I am not sure if it is worth the effort.
RHEL 4.4 contains a technology preview of frysk (http://sourceware.org/frysk), it would be useful to know if frysk can at least attach to such processes.
QE ack. Bastian, hopefully you can help us out with testing or provide a testcase?
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