topic Re: Question on pthread_exit in Operating System - Linux

Doubt with pthread_exit

rymani — Wed, 31 Oct 2007 01:24:06 GMT

Manual page of pthread_create says it will implicitly call pthread_exit when start_routine returns.
Is there way to know whether pthread_exit is called.
In c++ we can have a print statement in destructor function, which shows that destructor is called when an object is getting out.

Re: Question on pthread_exit

Dennis Handly — Sun, 18 Sep 2011 21:54:37 GMT

>In C++ we can have a print statement in destructor function, which shows that destructor is called when an object is getting out.

There is no connection between destructors and threads.
If you call pthread_exit, the destructors for any local objects will not be called. (At least on IPF.)

Since you are returning from the start function that already calls the destructors for any locals.

If you want to know if pthread_exit is called, put a breakpoint there.

Re: Doubt with pthread_exit

rymani — Fri, 02 Nov 2007 04:21:00 GMT

>If you want to know if pthread_exit is called, put a breakpoint there.

I'm not using an explicit call to pthread_exit, so i think i can't able to put a breakpoint.

>If you call pthread_exit, the destructors for any local objects will not be called.

If there is no explicit call to pthread_exit, will it lead to memory leak.

Re: Question on pthread_exit

Dennis Handly — Sun, 18 Sep 2011 21:55:33 GMT

>I'm not using an explicit call to pthread_exit, so I think I can't able to put a breakpoint.

No, you can still set a breakpoint there to see who else calls it. In my case I'm just returning out of the start routine:
(gdb) bt
#0 0x2000000076ef1a30:2 pthread_exit+0x72 /usr/lib/hpux32/libpthread.so.1
#1 0x2000000076ef04c0:0 __pthread_bound_body+0x190 libpthread.so.1

So libpthread automatically calls it.

>If there is no explicit call to pthread_exit, will it lead to memory leak.

No, you may leak memory if you don't return/throw back to your start routine.
Especially if you have locals that are STL containers. See:
http://docs.hp.com/en/10946/threads.htm
Pthreads (Posix Threads) Limitations

Re: Doubt with pthread_exit

rymani — Sat, 03 Nov 2007 05:19:33 GMT

Thanks Dennis, for the valuable suggestions provided.