possible problem with DBD::mysql and new mysql clients

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Hi all,

hopefully this email does not qualify me as a total noob, but I just =
wanted to point at a possible problem with DBD::mysql and new mysql =
clients.

We are running a few sites with mysql and OpenInteract as a web =
application server. Since now MySQL 4.1.7 is marked productive, we =
thought we should test it out.

So well, I upgraded to DBI 1.45 and DBD::2.9004 after installing the new =
client and all tests ran successfully. But when I start the web server, =
apache keeps on segfaulting.

So you might say - this is an OpenInteract bug or whatever, but this is =
what I tested:

- downgraded DBI to 1.44 and 1.43 and recompiled -> same result. I did =
this, because there where rumors about DBI 1.45 bugs.
- upgraded DBD::mysql to newes devel version -> same result.
- downgraded MySQL client to 4.0.21 gcc -> everything works ok.

The strange thing is, that all of my test scripts w/o apache worked ok, =
as did some OpenInteract test scripts that go w/o apache.

I `d be suppling more thorough input, if I knew how to approach this =
problem. Any hints ? The only thing I did not test ( yet ) is reading =
and storing BLOB data with the new client. OpenInteract uses =
Apache::Session to store session data - maybe this is what breaks the =
code.

So - if I got more, I`ll tell you. So far I just wanted to alert you, =
that there might be a problem - but maybe I am just doing s.th. wrong. =
If you got an idea, how I could generate some more useful input for you =
- please just tell me.

Regards

Andreas Nolte

andreas@kloeterbregen.de
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Re: possible problem with DBD::mysql and new mysql clients

On Sun, 14 Nov 2004, Andreas Nolte wrote:

> Hi rudy,
>
> hopefully this email does not qualify me as a total noob, but I just wanted to

nope. Segfaults always mean a bug (well unless you are getting a segfault
because you ran out of stack space. In which case, you might be able to think
of
it as a !bug?).

> point at a possible problem with DBD::mysql and new mysql clients.
>
> We are running a few sites with mysql and OpenInteract as a web application
> server. Since now MySQL 4.1.7 is marked productive, we thought we should test
> it out.
>
> So well, I upgraded to DBI 1.45 and DBD::2.9004 after installing the new
> client and all tests ran successfully. But when I start the web server, apache
> keeps on segfaulting.
>

I saw something similar on the Krang list, are you by chance using a
mysql_default_group connect option somewere? The person on Krang said that the
segfaulting went away when read_default_group= was removed form the connect
options, BTA when it comes to segfaults, any change to code can stop them, only
to have them pop up somwere else.

> So you might say - this is an OpenInteract bug or whatever, but this is what I
> tested:
>
> - downgraded DBI to 1.44 and 1.43 and recompiled -> same result. I did this,
> because there where rumors about DBI 1.45 bugs.
> - upgraded DBD::mysql to newes devel version -> same result.
> - downgraded MySQL client to 4.0.21 gcc -> everything works ok.
>
> The strange thing is, that all of my test scripts w/o apache worked ok, as did
> some OpenInteract test scripts that go w/o apache.
>

This is mod_perl, right? My first guess based on your description is that this
sounds like there might be an interaction between apache and the latest MySQL
client library that is causing a SIGSEGV (I wonder if php is having any
problems?).

> I `d be suppling more thorough input, if I knew how to approach this problem.
> Any hints ? The only thing I did not test ( yet ) is reading and storing BLOB
> data with the new client. OpenInteract uses Apache::Session to store session
> data - maybe this is what breaks the code.
>
> So - if I got more, I`ll tell you. So far I just wanted to alert you, that
> there might be a problem - but maybe I am just doing s.th. wrong. If you got
> an idea, how I could generate some more useful input for you - please just
> tell me.

1. A DBI->trace(9) of the offending section of code.

2. And then You could compile with -g and give me a backtrace from the core
file, also versions of apache and if you are using mod_perl the version of that.
And if you can, an isolated test script that will cause the segfault with a
minimum number of dependences (ideally just apache, DBD::mysql and mod_perl (if
you are using mod_perl))



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