When an unknown method is called in /usr/lib/libobjc.a it
calls abort() to halt the program with a SIGABRT. Running
such a program under gdb should then allow you to trace the
point of the call.
If the program is linked with -lthr then this works. If it
is linked with -lpthread then this does not work, and gdb
says "The program no longer exists."
This works on FreeBSD 4 and all other operating systems I
have tried it on. It also works, as stated, with libthr
on FreeBSD 5. The problem seems to be specific to libpthread
This has only shown up when trying to debug threaded code,
but the fact it is specific to a thread library and that
the code behaves everywhere else makes me wonder if something more
sinister is going on inside pthread.
This is only an issue when debugging, and if I need to track
down a bad method call I can always compile and run with libthr
in order to find it. Annoying but not the end of the world.
Simple test code:
main(int argc, char *argv)
id my_test = [Object new];
Compile with "cc -g test.m -lobj -lpthread" and run under gdb.
Compiling with "cc -g test.m -lobj -lthr" behaves as expected.
A bit more info - this problem seems to be related to the scope of the threads
as if I run the test program with LIBPTHREAD_SYSTEM_SCOPE defined then
the debugger catches the abort correctly and lets me trace the offending
libkse is no longer supported and libthr is the only threading library used by modern versions of FreeBSD.
Heh, indeed! In addition modern FreeBSD has no objective c runtime and doesnt have the GNU compiler, so all kind of moot! Thanks for looking through. I do wonder what it was, however.