On Sun, Dec 08, 2002 at 09:27:49PM -0800, Sharath wrote: > Amit, > > the threading library on Linux is a a bit different > from the normal 'threads'. > > Strictly threads are not children of a process as a > fork(...) does. When a child of a process terminated, > the parent process gets a SIGCHLD. However when a > thread terminates is doesn't. > > The way threading is implemented on linux (where every > thread is represented as a child) is a quirk. > > The thread (though it appears as a child) is in fact > *not a true cild* of the process hence waitpid(...) > rightly returns. You shouldn't be using waitpid(...) > to wait on a thread rather use pthread_join(...) but > then you need to pass on the pthread_t that you got > when you created it. It is a true child. But it's a child of the pthreads master thread. When you first pthread_create, it clones and the _child_ continues on, while the _parent_ becomes the master thread. Then, the child (which continues the work of the original process) sends a message to the master and the master clones the new thread. When you call pthread_join, the message is passed to the master and the master issues waitpid. That's the only way how to assure, that any thread can join any other thread. ------------------------------------------------------------------------------- Jan 'Bulb' Hudec <bulb@ucw.cz> -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
