From: "Jonathan" <[EMAIL PROTECTED]> Subject: Re: Apache::Session::MySQL lock troubles
> looks like DBI stops talking to mysql > > when this happens, is apache hanging? > > or does it just crash on one page, and then continually crash on > subsequent pages? Yeah, apache freezes ( was freezing ) solid. No more entries in the access_log for subequent requests. > a few ideas: > a > are you using the same dh / $dbh for session as the rest of your site? > if so, try creating a new mysql db for sessions only. > there could be some locking issue caused by other queries. Yes, the whole site is (supposed to be) using the same dh. I seemed to have fixed it, though I didn't find the exact reason. Changing the way a $dbh was built in an unrelated picece of mason code seemed to fix it. A $dbh was being made via DBI->connect in a <% shared %> section and used in <% method %>s in an autohandler. Switching to what seems to me to be a more sane usage, I haven't had a hang yet, even with giving -n 5000 -c 10 ( a VERY heavy usage for this site ) to ab. I think Apache::Session was trying to release a lock that it didn't create. Another guess is identical pieces of code with improperly scoped variables were trying to work simultaneously after a redirect. > b > are you using Apache::DBI or another persistence provider? > i'm thinking that *maybe* you're not, and mysql is unhappy that > you're slamming it with constant connects. Yeah, it does use Apache::DBI > c > if this is a dev box, try enabling the query log and slow log in > mysql, and enable tracing in DBI > if you can reproduce, see if mysql is logging it as a slow log, and > see if mysql or DBI did something that didn't unlock a table > be warned though - mysql query log can grow gigantic, and DBI > tracing can be verbose I've gotten it to hang on dev and staging, but of course it seems to do it the most on production :-). > d > assuming you're on a nix/bsd ( there were some files in the root of > that page that suggested such) tail the logs while you stresstest. > Help! I'm drowning in log entries :-) Thank you so much for your very useful tips! trwww > > On Feb 26, 2006, at 4:29 PM, Todd W wrote: > > > Apache::Session is occasionally hanging pages. If I stop the > > server, I find > > the following in the error log: > > > > http://waveright.homeip.net/~trwww/code/pmsi/4tp-bug.txt > > > > using pre and post statment warn()s, I found that the line that > > causes the > > hang is: > > > > eval { > > tie %{$session}, 'Apache::Session::MySQL', $session_key, > > { Handle => $dbh, LockHandle => $dbh } ; > > } ; > > > > The only way I can "duplicate" it is by pounding the sever with ab. > > > > Once it hangs, it says hung ( can't make any other requests ). A > > restart > > always gets it going agian. > > > > Thanks in advance for any advice! > > > > Todd W. > > > > > > > >
