Date: Tue, 24 Jun 2008 00:23:32 -0700 From: Julian Elischer <julian@elischer.org> To: Saradhi Kothapalli <saikothapalli@gmail.com> Cc: freebsd-threads@freebsd.org Subject: Re: Threads stuck in kserel state Message-ID: <4860A0F4.1040304@elischer.org> In-Reply-To: <52db57fb0806232344y95eb159ra2dd43a4462ee082@mail.gmail.com> References: <52db57fb0806232344y95eb159ra2dd43a4462ee082@mail.gmail.com>
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Saradhi Kothapalli wrote:
> Hi
>
> I am running FreeBSD 5.4 on my machine. When i run mpd on it, i see it stuck
> in kserel state.
> I have written a sample thread program to check whether its an mpd problem
> or not.
>
> Observations on the Sample test program:
>
> I have created only one thread from the process, but the top output shows
> total 3 entries.
yes
The thread you started in sleeping in ttyin.
the thread library greated a background thread to handle signal
delivery (ksesig).
When the main thread did ttyin, it blocked, so a third thread was
created to make sure that if any other work had to be done there was a
thread to do it. that third thread is waiting for more work to appear,
and in kserel (kse-release).
> Even when the thread has finished i see 2 entries that to one in kserel and
> other in ksesig state.
>
> Is the main process stuck in "kserel" state or is it an expected behavior?
> Is it because of KSE the other thread is shown in top output? Is the state
> "ksesig" signifies that it is waiting for an event to occur?
>
>
> Thanks in advance for the help.
>
> Regards
> Saradhi
>
>
> The Sample Test program:
>
> #include <stdio.h>
> #include <pthread.h>
> #include <pdel/structs/structs.h>
> #include <pdel/structs/type/array.h>
> #include <pdel/util/typed_mem.h>
> #include <pdel/util/pevent.h>
> #include <pdel/util/paction.h>
> #include <pdel/util/ghash.h>
> #include <unistd.h>
>
> pthread_mutex_t mutex;
>
> static void
> startFn(void * arg)
> {
> printf("\n *** Thread Start Function *** \n");
> getchar();
> return;
> }
>
> static void
> endFn(void * arg, int done)
> {
> printf("\n *** Thread End Function *** \n");
> getchar();
> return;
> }
>
> static void
> thrStart()
> {
> struct paction * thr;
> uint32_t temp;
>
> if ( paction_start(&thr, &mutex, startFn, endFn, &temp) == -1 )
> {
> printf("\n *** Failed to start thread *** \n ");
> getchar();
> }
> return ;
> }
>
> int main()
> {
>
> int ret = pthread_mutex_init(&mutex, NULL);
> if ( ret != 0 )
> {
> printf("\n *** Mutex initialization Failed *** \n");
> return -1;
> }
>
> printf("\n *** calling thread start *** \n ");
> getchar();
>
> thrStart();
>
> for ( ; ; )
> {
> sleep(1);
> }
> return 0;
> }
>
> THE TOP OUTPUT WITH THREAD DISPLAY TURNED ON:
>
> When the thread is in existence (both during start and end function):
> -----------------------------------------------------------------------------------------------------
>
> 18387 root 20 0 3384K 1760K ksesig 0:00 0.00% 0.00% thrd
> 18387 root 20 0 3384K 1760K kserel 0:00 0.00% 0.00% thrd
> 18387 root 5 0 3384K 1760K ttyin 0:00 0.00% 0.00% thrd
>
> After the thread execution is completed (the for loop):
> ---------------------------------------------------------
> 18387 root 20 0 3384K 1752K ksesig 0:00 0.00% 0.00% thrd
> 18387 root 20 0 3384K 1752K kserel 0:00 0.00% 0.00% thrd
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