Hi, Raseel You said that: 1. tgid <==> getpid() <==> pid of the process which invokes (call pthread_create) the threads 2. tid <==> pthread_self() <==> pid of the particular thread I think the the process which calls pthread_create() is the thread group leader, because it is first lightweight process in the group. So, it's tgid == it's pid. As your opinion, there should be a thread whose tgid and pid are equal, i.e., getpid() == pthread_self(). Am I wrong? Regard, Cheng -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/