Re: MySQL crashes on amd64

Greg 'groggy' Lehey wrote:
> [Sequence recovered--see http://www.lemis.com/email/email-format.html]
> 
> On Thursday, 13 October 2005 at 17:56:11 +0200, Stefan Cars wrote:
> 
>>Greg 'groggy' Lehey wrote:
>>
>>>On Wednesday, 12 October 2005 at  9:27:17 +0200, Stefan Cars wrote:
>>>
>>>
>>>>Hi!
>>>>
>>>>We are having troubles with MySQL 4.1 on a amd64 (it's crashing
>>>>randomly with Seg fault, signal 11. gdb bt says: Cannot access
>>>>memory at address 0x800000000000). We have got information saying
>>>>this is a 64bit related issue and should be fixed by using the i386
>>>>version instead of amd64 (this is an Intel Xeon).
>>>
>>>Where did you get that information from?
> 
> 
> I'd still like to know an answer to this question.

I got information from a guy working on the floor below us, although his 
thoughts were only that "amd64 is a bit unstable so that should be the 
problem"

> 
> 
>>>>What is the way to go when moving from amd64 to i386 ?
>>>
>>>If you mean "how do I install an i386 kernel on this machine", I can't
>>>think of any way except to start from scratch.  It would be a good
>>>idea to install a separate disk, so you can access the configuration
>>>files and the database on the old disk.  But before doing this, I'd be
>>>very interested in knowing what the problem is.  Is the backtrace
>>>always the same?  Where does it crash?
>>
>>After doing some testing this is what I found out:
>>
>>1) Exchanging memory on the machine did not work. Same error.
>>2) Trying it on another 64 bit machine with same FreeBSD (RC1) creates
>>EXACT same problem
>>3) Installing the i386 version of RC1 instead of amd64 on the same
>>machines and it works terrific. No crash.
> 
> 
> Hmm.  That's interesting.  This is obviously not a hardware issue.
> 
> 
>>The bt is always the same and it always crash the same, look here:
>>
>>#784 0x0000000000000000 in ?? ()
>>#785 0x247c8d48002454ff in ?? ()
>>#786 0x01a1c0c748006a10 in ?? ()
>>#787 0x66fdebf4050f0000 in ?? ()
>>#788 0x9066669066669066 in ?? ()
>>#789 0x00007fffffffe778 in ?? ()
>>#790 0x0000000000000006 in ?? ()
>>#791 0x00007fffffffe7b0 in ?? ()
>>#792 0x0000000000000017 in ?? ()
>>Cannot access memory at address 0x800000000000
> 
> 
> Without function names instead of ??, it's impossible to say what's
> happening here.  You'd need to build with debug symbols.
> 
> Since you've been told that this is an issue, it would be good to know
> more.  As we've mentioned on other threads, there are reasons to
> believe that there are problems with the threading libraries, but
> currently we don't have enough information to investigate them.  Note
> that the other recent thread refers to problems running in the
> configuration you have just installed: see
> http://bugs.mysql.com/bug.php?id=12251 for more details.  If you see
> anything similar, please let us know.
> 


After doing alot of testing and trying this is some more new information:

It actually DO crash on i386 FreeBSD 6.0-RC1 aswell, but very seldom 
(around once every 4-5th hour, this time we get a Signal 10 instead, see 
below). The errors are reproducable for MySQL 4.1.15 and MySQL 5.0.15 so 
the problem still exists on 5.0.15. Of course we have tried on different 
  machines aswell to make sure it's not hardware related. On a FreeBSD 
5.3 machine Mysql 4.1.15 works fine.


mysqld got signal 10;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
We will try our best to scrape up some info that will hopefully help 
diagnose
the problem, but since we have already crashed, something is definitely 
wrong
and this may fail.

key_buffer_size=1048576
read_buffer_size=131072
max_used_connections=99
max_connections=400
threads_connected=44
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections 
= 461820 K
bytes of memory
Hope that's ok; if not, decrease some variables in the equation.