Re: cvs commit: src/lib/libthread_xu Makefile pthread.map src/lib/libthread_xu/arch Makefile.inc src/lib/libthread_xu/arch/alpha Makefile.inc src/lib/libthread_xu/arch/alpha/alpha pthread_md.c src/lib/libthread_xu/arch/alpha/include pthread_md.h src/lib/libthread_xu/arch/amd64 ...

[David Xu <davidxu@xxxxxxxxxxx>]

Matthew Dillon wrote:

> :This is fine to me, did you consider how to exit whole process not
> :just a single thread ? right now, I am using _exit(), but it only
> :exits current thread, other threads can not be shutdown.
>
>    The problem with using _exit() to exit all threads is that there
>    is no way to notify the other threads of the event, and there are
>    cases where we might want that feature.  I think what we want here
>    is a signal rather then a system call.
>
>    Since we are already going to create a distinction in the signal handling
>    between vectored and shared signals, there is no reason why we couldn't
>    also create the concept of a 'broadcast' signal, that all threads get.
>    SIGKILL, SIGSTOP, SIGTSTP, SIGCONT... these would all be broadcast
>    signals by default.
>
>    We would implement it via sigaction().  We would add a SA_BROADCAST
>    flag to handle broadcast signals, and we would also add a SA_VECTORED
>    flag to differentiate between shared signals and targeted signals.
>
> 					-Matt
> 					Matthew Dillon 
> 					<dillon@xxxxxxxxxxxxx>
>
>
>  
There are problems, first, when debugging,  debugger will catch
the signal, second is important, exit() should save a value in
kernel zoombie proc structure, so parent waitpid() on it can get
the exit code, signal can not provide this feature.
Linux has exit_group() which I think is used to implement exit().
FreeBSD introduced thr_exit and kse_exit to exit single thread,
and leave orignal exit() to exit whole process.

David Xu