Thank you Dan!
I do not have access to a FreeBSD computer during this weekend but
your stack prints already tell the origin of the problem.
I have implemented my own mutexes in the purpose that I can use
an assembler instruction for the atomic test-and-set operation
needed in a mutex. But for now I have done the test-and-set
with pthread_mutex_trylock: it provides an atomic operation
on an OS mutex which I can use in place of test-and-set.
It seems that if a thread does not acquire a mutex with the
first try, then something goes wrong and the thread is left in a loop.
The stack prints show that FreeBSD uses a spin wait also in the
case a trylock fails. This may be associated with the problem.
More logical would be that FreeBSD would return with a failure
code if trylock fails.
A fix would be to replace pthread_mutex_trylock with
the XCHG instruction to implement test-and-set. But that would not
work on non-Intel FreeBSD platforms.
I will dig into the FreeBSD documentation and try to find a
solution from there.
Best regards,
Heikki
At 03:52 PM 3/30/01 -0600, you wrote:
>In the last episode (Mar 30), Heikki Tuuri said:
>> The FreeBSD bug is known. I will run tests on our FreeBSD machine in
>> the next few days. Obviously there is something wrong with the
>> FreeBSD port. Was it so that it hung and used 100 % of CPU? That has
>> been reported also from Italy.
>
>I have a similar problem, on FreeBSD 5 (i.e. -current). I can insert
>records one at a time with no problem, but if I try to update more than
>~250 records at a time, it hangs, consuming 100% cpu. gdb'ing a corefile of
>the process, it looks like a mutex/spinlock problem of some sort.
>Deleting records dies if I delete between 100 and 150 records in one
>go. Does innobase create a mutex for each record processed? Maybe
>there's a limit on 256 held mutices per thread on FreeBSD or something.
>
>-- mysqld hung on "insert into temp (value) select ip from iptable limit 300":
>(gdb) thread apply all bt
>
>Thread 1 (process 764):
>#0 0x28288163 in _get_curthread ()
> at /usr/src/lib/libc_r/uthread/uthread_kern.c:1145
>#1 0x28280064 in _spinlock_debug (lck=0xbfaa9ecc,
> fname=0x28280138
"\203â\020\205â\017\2055Â Â Â \213\205â¿â Â Â \213U\b\211B\004\213E\f\
211B\b\213E\020\211B\f\215Ãâªâ   [^_\211â]â$FreeBSD:
src/lib/libc_r/arch/i386/_atomic_lock.S,v 1.3 1999/08/28 00:03:01 peter Exp
$", lineno=149551536)
> at /usr/src/lib/libc_r/uthread/uthread_spinlock.c:83
>#2 0x282854d6 in mutex_trylock_common (mutex=0xbfaa9ecc)
> at /usr/src/lib/libc_r/uthread/uthread_mutex.c:311
>#3 0x28285712 in __pthread_mutex_trylock (mutex=0x8ea3090)
> at /usr/src/lib/libc_r/uthread/uthread_mutex.c:441
>#4 0x8193d4b in mutex_spin_wait (mutex=0x8ea308c) at ../include/os0sync.ic:38
>#5 0x8126ead in srv_master_thread (arg=0x0) at ../include/sync0sync.ic:220
>#6 0x2827f18c in _thread_start ()
> at /usr/src/lib/libc_r/uthread/uthread_create.c:326
>#7 0x0 in ?? ()
>(gdb)
>
>
>-- mysqld hung on "delete from temp limit 150":
>(gdb) info threads;
>* 1 process 26111 0x28361b54 in gettimeofday () from /usr/lib/libc.so.5
>(gdb) where
>#0 0x28361b54 in gettimeofday () from /usr/lib/libc.so.5
>#1 0x28280949 in _thread_sig_handler (sig=0, info=0x828a660, ucp=0x282808d1)
> at /usr/src/lib/libc_r/uthread/uthread_sig.c:93
>#2 0xbfbfffac in ?? ()
>#3 0x28287ffb in _thread_kern_sig_defer ()
> at /usr/src/lib/libc_r/uthread/uthread_kern.c:1049
>#4 0x282854bf in mutex_trylock_common (mutex=0x0)
> at /usr/src/lib/libc_r/uthread/uthread_mutex.c:308
>#5 0x28285712 in __pthread_mutex_trylock (mutex=0x8ea3210)
> at /usr/src/lib/libc_r/uthread/uthread_mutex.c:441
>#6 0x8193d4b in mutex_spin_wait (mutex=0x8ea320c) at ../include/os0sync.ic:38
>#7 0x8165a84 in buf_page_get_gen (space=0, offset=6, rw_latch=2, guess=0x0,
> mode=10, mtr=0xbfaa95d0) at ../include/sync0sync.ic:220
>#8 0x81576d9 in trx_purge_truncate_rseg_history (rseg=0x8ebd10c,
> limit_trx_no={high = 0, low = 7946}, limit_undo_no={high = 0, low = 0})
> at ../include/trx0rseg.ic:25
>#9 0x8157bdd in trx_purge_truncate_history () at trx0purge.c:545
>#10 0x81589c7 in trx_purge_fetch_next_rec (roll_ptr=0xbfaa9ee4,
> cell=0x8ec016c, heap=0x8ebfe0c) at trx0purge.c:564
>#11 0x813a2b6 in row_purge (node=0x8ec0134, thr=0x8ec00d4) at row0purge.c:481
>#12 0x813a4fe in row_purge_step (thr=0x8ec00d4) at row0purge.c:548
>#13 0x8129aa2 in que_run_threads (thr=0x8ec00d4) at que0que.c:1223
>#14 0x8158f95 in trx_purge () at trx0purge.c:1050
>#15 0x8126fb5 in srv_master_thread (arg=0x0) at srv0srv.c:1901
>#16 0x2827f18c in _thread_start ()
> at /usr/src/lib/libc_r/uthread/uthread_create.c:326
>#17 0x0 in ?? ()
>(gdb)
>
>
>--
> Dan Nelson
> [EMAIL PROTECTED]
>
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