[rt-users] version 3.6.1--dreaded infinite login

[Jim Brandt]

I think I've found some extra information regarding the login problem, 
at least while using Apache::Session::File on my (Mac OS X server, perl 
5.8.6) system. After doing a bunch of debugging, I've found that 
Apache::Session gets itself in a state where it can't get a write lock 
on the session file. Apache::Session doesn't error check it's flock 
calls, so it happens silently.

I found this post on perlmonks that suggested manual calls to DESTROY 
can help the problem:

http://perlmonks.org/?node_id=435977

so I put one near the end of autohandler.

However, when I did this, the server just hung. Looking into the 
Apache::Session::Lock::File code, I found that it's trying to get an 
exclusive lock and it's blocking when trying to write. So I hacked it on 
our dev system to just return when it can't get the lock. After doing 
that, my log has a bunch of these:

[warning]: Unable to get exclusive lock (Resource temporarily 
unavailable). Moving along... at 
/Library/Perl/5.8.6/Apache/Session/Lock/File.pm

I then added a call to release_all_locks, thinking it might help in the 
final write to the session file.

After these hacks, I did get the multiple login issue to go away. But, I 
still get several of the above warnings on the initial page load.

I don't consider this a true fix since I'm not sure of the repercussions 
of manually releasing the locks, but I think it demonstrates that part 
of the problem is in Apache::Session::File (or the file system itself) 
somewhere. The only information I could find to indicate what's 
happening is that something isn't playing nice with the file locks. And 
I can't explain why it appears to resolve itself after a few logins. Is 
there something special happening on the first login that triggers these 
locking problems?

I'm sorry I can't present a solution, but I hope this might help move 
toward a fix or workaround.

Jim


-- 
Jim Brandt
Administrative Computing Services
University at Buffalo