Hi all,
On 5/10/06, Manish Regmi <regmi.manish@xxxxxxxxx> wrote:> On 5/9/06, cheng long <kevinclcn@xxxxxxxxx> wrote:> > > Why do you think so?> > > pid is allocated by pid types. ie. pid is allocated differently for> > > process (i mean those created with CLONE_THREAD) and threads. so they> > > are so different.> >> > #include <stdio.h>> > #include <pthread.h>> > int main()> > {> > printf("main pid: %u\n", getpid());> > printf("main thread id: %u\n", pthread_self());> > return 0;> > }> >> > As we know, the tid is the first thread's pid, but the above progrom> > prints two different number, how's that?> >>> In this case tgid and pid must be same. it seems that pthread_self()> cannot be used without pthread_create. Don't know for sure.>
pthread_self() will return the id of the thread, i,e. , the tid. Thisis unique for each thread.On the other hand, getpid() (get PROCESS id) wil return the pid of thecurrent _PROCESS_ , i.e., this is the tgid which will be same for allthe threads invoked from within that process.
To summarize:tgid <==> getpid() <==> pid of the process which invokes (callpthread_create) the threads and is common to all threads invoked bythe process.tid <==> pthread_self() <==> pid of the particular thread, and isunique to each process....
And as Manish pointed out, if you call pthread_self() outside the"thread context", it gives some different id.
Try this for some clarity :
#include <stdio.h>#include <pthread.h>void * func (void * argc){ int i = (int)argc; printf ("In the thread %d : %u\n",i,pthread_self()); printf ("In the thread %d : %u\n",i,gettid());}int main(){ pthread_t th[2]; int i,ret; printf("main pid: %u\n", getpid()); for (i = 0; i < 3; i++) ret = pthread_create (&th[i], NULL, func, (void *)i); pthread_join(th[0], NULL); return 0;}--Raseel.��������!���W��v������ޗ��{��f���� ��ޖw�n'�������Y�����
