Re: Why won't slapd shutdown (kill -0)?

From: Sean McNeil <sean_at_mcneil.com>
Date: Wed, 17 Nov 2004 12:56:48 -0800
On Wed, 2004-11-17 at 10:28 -0800, Doug White wrote: 
> On Tue, 16 Nov 2004, Sean McNeil wrote:
> 
> > This has been happening for a long time with current and hasn't been
> > resolved.  When I start up slapd, I cannot stop it without kill -9 ing
> > it.  It would appear stuck in kse and probably has something to do with
> > kill -0:
> 
> Mind expanding on this? The backtrace looks normal for a pthread process.
> kill -0 just tests signal delivery; the process is completely unaware that
> the probe occured, though.  The process may also be unkillable if its
> stuck in some sort of I/O wait.
> 
> Is the server busy when you signal it?

Oh, OK.  I didn't look at /usr/local/etc/rc.subr too closely.  I have
additional information, though....

It appears that all the threads are destroyed yet it is still in the
thread processing loop.  The process is no longer active at all.  I just
had a similar problem happen with vlc where I closed it yet it is
hanging in the same place as slapd with all the threads gone.

Here is the one from vlc:

(gdb) bt full
#0  _thr_sched_switch_unlocked (curthread=0x955000) at pthread_md.h:226
        psf = {psf_valid = 0, psf_flags = 0, psf_cancelflags = 29952806,
  psf_interrupted = 8, psf_timeout = 11279168, psf_signo = 0,
  psf_state = 11279168, psf_wait_data = {mutex = 0x8, cond = 0x8, lock =
0x8,
    sigwait = 0x8}, psf_wakeup_time = {tv_sec = 0, tv_nsec = 0},
psf_sigset = {
    __bits = {29950366, 8, 9860096, 0}}, psf_sigmask = {__bits =
{9752576, 1,
      9860096, 0}}, psf_seqno = 29995347}
        curkse = (struct kse *) 0x952000
        resume_once = 0
#1  0x0000000801c925e0 in _thr_sched_switch (curthread=0x955000)
    at /usr/src/lib/libpthread/thread/thr_kern.c:607
No locals.
#2  0x0000000801c85cb4 in _pthread_join (pthread=0x967400,
thread_return=0x0)
    at /usr/src/lib/libpthread/thread/thr_join.c:133
        curthread = (struct pthread *) 0x955000
        tmp = (void *) 0x0
        crit = 0x0
        ret = 0
#3  0x0000000000431749 in __vlc_thread_join (p_this=0xad4800,
    psz_file=0x6a283c "src/playlist/playlist.c", i_line=130)
    at src/misc/threads.c:716
        i_ret = 1
#4  0x000000000040ee1a in playlist_Destroy (p_playlist=0xad4800)
---Type <return> to continue, or q <return> to quit---
    at src/playlist/playlist.c:130
No locals.
#5  0x000000000040c400 in VLC_CleanUp (i_object=0) at src/libvlc.c:831
        p_intf = (intf_thread_t *) 0xad4800
        p_playlist = (playlist_t *) 0xad4800
        p_vout = (vout_thread_t *) 0xad4800
        p_aout = (aout_instance_t *) 0xad4800
        p_announce = (announce_handler_t *) 0xad4800
        p_vlc = (vlc_t *) 0x94d400
#6  0x0000000000407415 in main (i_argc=1, ppsz_argv=0x7fffffffe940)
    at src/vlc.c:108
        i_ret = 0

and here is a full trace of slapd:

(gdb) bt full
#0  0x000000080142e914 in kse_release () at kse_release.S:2
No locals.
#1  0x0000000801428e49 in kse_wait (kse=0x62a000, td_wait=0x0,
sigseqno=0)
    at /usr/src/lib/libpthread/thread/thr_kern.c:1843
        ts = {tv_sec = 7647232, tv_nsec = 7647232}
        ts_sleep = {tv_sec = 60, tv_nsec = 0}
        saved_flags = 0
#2  0x0000000801427078 in kse_sched_multi (kmbx=0x62efa0)
    at /usr/src/lib/libpthread/thread/thr_kern.c:1039
        curkse = (struct kse *) 0x62a000
        curthread = (struct pthread *) 0x0
        td_wait = (struct pthread *) 0x62a068
        curframe = (struct pthread_sigframe *) 0x17f
        ret = 383
#3  0x000000080142afbf in _amd64_enter_uts ()
    at /usr/src/lib/libpthread/arch/amd64/amd64/enter_uts.S:40
No locals.
#4  0x0000000000000000 in ?? ()
No symbol table info available.
#5  0x000000000062f000 in ?? ()
No symbol table info available.
#6  0x000000000062a000 in ?? ()
No symbol table info available.
---Type <return> to continue, or q <return> to quit---
#7  0x0000000000000000 in ?? ()
No symbol table info available.
#8  0x0000000000000000 in ?? ()
No symbol table info available.
#9  0x0000000000000000 in ?? ()
No symbol table info available.
#10 0x0000000000000000 in ?? ()
No symbol table info available.
#11 0x0000000000000000 in ?? ()
No symbol table info available.
#12 0x0000000000000001 in ?? ()
No symbol table info available.
#13 0x0000000801426dd0 in _thr_sched_switch_unlocked ()
    at /usr/src/lib/libpthread/thread/thr_kern.c:904
        free_kseq = {tqh_first = 0x0, tqh_last = 0x801534810}
        gc_ksegq = {tqh_first = 0x0, tqh_last = 0x801534840}
        next_uniqueid = 7
        active_kse_groupq = {tqh_first = 0x62f100, tqh_last = 0x748020}
        active_kse_count = 2
        free_threadq = {tqh_first = 0x0, tqh_last = 0x801534890}
        free_kse_count = 0
        active_kseq = {tqh_first = 0x62a000, tqh_last = 0x6c9220}
        free_kse_groupq = {tqh_first = 0x0, tqh_last = 0x801534820}
---Type <return> to continue, or q <return> to quit---
        kse_lock = {l_head = 0x6291c0, l_tail = 0x6291c0,
  l_type = LCK_ADAPTIVE, l_wait = 0x801426150 <_kse_lock_wait>,
  l_wakeup = 0x8014261e0 <_kse_lock_wakeup>}
        active_kseg_count = 2
        inited = 1
        free_thread_count = 0
        free_kseg_count = 0
        thr_hashtable = {{lh_first = 0x0} <repeats 44 times>, {
    lh_first = 0x6c3c00}, {lh_first = 0x0}, {lh_first = 0x0}, {
    lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x1874400}, {
    lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, {lh_first =
0x0}, {
    lh_first = 0x74b000}, {lh_first = 0x0} <repeats 15 times>, {
    lh_first = 0x74b800}, {lh_first = 0x0}, {lh_first = 0x0}, {
    lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, {lh_first =
0x0}, {
    lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x632000}, {
    lh_first = 0x0} <repeats 23 times>, {lh_first = 0x29ab400}, {
    lh_first = 0x0}, {lh_first = 0x0}, {lh_first = 0x0}, {lh_first =
0x0}, {
    lh_first = 0x0}, {lh_first = 0x2983c00}, {
    lh_first = 0x0} <repeats 17 times>}
        thread_lock = {l_head = 0x6291e0, l_tail = 0x6291e0,
  l_type = LCK_ADAPTIVE, l_wait = 0x801426150 <_kse_lock_wait>,
  l_wakeup = 0x8014261e0 <_kse_lock_wakeup>}
        _tcb_mutex = 0x628380
Previous frame inner to this frame (corrupt stack?)

which looks like total garbage.  Looking at each thread I see that there
is only a thread 1,2, and 3:

(gdb) thread 1
[Switching to thread 1 (Thread 6 (LWP 100177))]#0  0x000000080142e914 in
kse_release () at kse_release.S:2
2       RSYSCALL(kse_release)
(gdb) bt
#0  0x000000080142e914 in kse_release () at kse_release.S:2
#1  0x000000080141d926 in sig_daemon (arg=0x7fffffefef70)
    at /usr/src/lib/libpthread/thread/thr_sig.c:216
#2  0x0000000801426db5 in kse_sched_single (kmbx=0x7fffffefef70)
    at /usr/src/lib/libpthread/thread/thr_kern.c:902

(gdb) thread 2
[Switching to thread 2 (Thread 7 (sleeping))]#0
_thr_sched_switch_unlocked (
    curthread=0x632000) at pthread_md.h:226
226             if (ret == 0) {
Current language:  auto; currently c
(gdb) bt
#0  _thr_sched_switch_unlocked (curthread=0x632000) at pthread_md.h:226
#1  0x00000008014265e0 in _thr_sched_switch (curthread=0x632000)
    at /usr/src/lib/libpthread/thread/thr_kern.c:607
#2  0x0000000801419cb4 in _pthread_join (pthread=0x74b000,
thread_return=0x0)
    at /usr/src/lib/libpthread/thread/thr_join.c:133
#3  0x0000000800719d09 in ldap_pvt_thread_join (thread=0x800609070,
    thread_return=0x62a068) at thr_posix.c:165

(gdb) thread 3
[Switching to thread 3 (LWP 100148)]#0  0x000000080142e914 in
kse_release ()
    at kse_release.S:2
2       RSYSCALL(kse_release)
Current language:  auto; currently asm
(gdb) bt
#0  0x000000080142e914 in kse_release () at kse_release.S:2
#1  0x0000000801428e49 in kse_wait (kse=0x62a000, td_wait=0x0,
sigseqno=0)
    at /usr/src/lib/libpthread/thread/thr_kern.c:1843
#2  0x0000000801427078 in kse_sched_multi (kmbx=0x62efa0)
    at /usr/src/lib/libpthread/thread/thr_kern.c:1039
#3  0x000000080142afbf in _amd64_enter_uts ()
    at /usr/src/lib/libpthread/arch/amd64/amd64/enter_uts.S:40

> >
> > (gdb) bt
> > #0  0x000000080142e914 in kse_release () at kse_release.S:2
> > #1  0x0000000801428e49 in kse_wait (kse=0x62a000, td_wait=0x0,
> > sigseqno=0)
> >     at /usr/src/lib/libpthread/thread/thr_kern.c:1843
> > #2  0x0000000801427078 in kse_sched_multi (kmbx=0x62efa0)
> >     at /usr/src/lib/libpthread/thread/thr_kern.c:1039
> > #3  0x000000080142afbf in _amd64_enter_uts ()
> >     at /usr/src/lib/libpthread/arch/amd64/amd64/enter_uts.S:40
> > #4  0x0000000000000000 in ?? ()
> > #5  0x000000000062f000 in ?? ()
> > #6  0x000000000062a000 in ?? ()
> > #7  0x0000000000000000 in ?? ()
> > #8  0x0000000000000000 in ?? ()
> > #9  0x0000000000000000 in ?? ()
> > #10 0x0000000000000000 in ?? ()
> > #11 0x0000000000000000 in ?? ()
> > #12 0x0000000000000001 in ?? ()
> > #13 0x0000000801426dd0 in _thr_sched_switch_unlocked ()
> >     at /usr/src/lib/libpthread/thread/thr_kern.c:904
> > Previous frame inner to this frame (corrupt stack?)
> >
> >
> 

Received on Wed Nov 17 2004 - 19:56:51 UTC

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