Strange MySQL issues

[smarko]

I might have (highly propably) MySQL related problem. Maybe you could help me understand this issue better.

One of MySQL based forums (phpBB), which I administrate, some times (not too often, but atleast ones a day. many users have confirmed this) shows error "Fatal error: Maximum execution time of 10 seconds exceeded". What is so strange here, is, that it seems to be impossible to connect that error to amount of users on board or to amount of mysql -connections / -queries. It can happen at night, when I'm the only user on board, but it could also work great, even with some 20 concurrent users, in the afternoon.

Database seems to be ok, when viewed with phpMyAdmin.. but naturally I can't be absolutely sure if it's really ok.

So what I'm actually asking? I wish you could give me some hints how to continue solving this problem. At phpBB's support forum I got only hints like "increase amount of script execution time on server". Not good enough. I want to undersstand better the logic behind the error. I don't like in feeling, that the board might break again anytime, even with increased values.

It goes even more stranger, when my testboard (me being it's only user) show fatal errors 10 times in a row and at the very same time the actual forum works like a charm.

I would be very grateful for any kind of help.

[Dylan Leblanc]

It might be that part of the database has become quite large, and so queries are taking a long time to return their values.

[smarko]

That can't be the case. I only see mysql query times of 0.243545 seconds or so, but sometimes it just goes wild and show that fatal error. PhpBB -forum engine should handle my 800 registered users (20-30 concurrent users at daytime) and my 30 000+ posts quite easily as it can handle much much more in other other forums. ISP has limited concurrent connections to database to 50 connections, but that should be enough, atleast for now.

[Dylan Leblanc]

I have heard of another issue with that forum program, to do with the session table not being emptied, and I think there was a fix for it.

So your problem might be a bug of sorts with the code, have you checked with the people who make the program?

[smarko]

No, I don't think this is related to that as then forum would say "Error creating new session" or something like that. There has been only fatal erros mentioned above. And I did asked at phpbb's support forums (see above). No help, atleast not yet.