Re: MySQL Server crashes - spawning too many threads.

[Erin ONeill]

Yes we're php pconnects (java & I believe perl also have database connection pooling and I think they also call it pconnect). I come from the Oracle & java world where pconnects were/are pretty standard. But it seems that php pconnects with really busy forums can cause problems. BUT that said -- the jury is still out on this. I want to hear what the gurus are saying about this (anyone working at Friendster on this forum??)

I'm wondering if my Linux has been set up for MySQL and if MySQL was compiled correctly? (Programmers tend to view OS problems as hardware a lot, even though it is really software, it's just not their code). I'm really sure it's not the physical PC/intel box as we got a new and fancier box and the problems have still persisted. And they are intermittent which are the worst kind! I also come from the solaris world and you used to have to set up solaris to handle a large number of open files, but no more. And I found the doc online for linux so it sounds like linux still needs to have this manually done rather than being the default like it is with solaris now. But I don't know. I've never built a linux box outside of helping a friend go thru it.

What seems to be happening is that MySQL opens too many files and threads for the OS and things slow to a crawl and eventually crash. My admins won't let me set the table_cache higher than 1240, even though the stats tell me I should (our MySQL seems to like it set to about 2000-2200). And our max open files (egads I'm away from my books so I've forgotten the correct term) is set to something like 2850 which seems really low to me. Makes me really not appreaciate linux at all. YET I know that there are systems set up that are MASSIVE and using lamp (Friendster). It can be done.

The last time I saw this was in the mid-90s and we moved from a solaris box to an SGI and the problem was solved. You can bet Sun worked hard to fix this problem with too many simultaneous connections. I think that's where the connection pooling came from too but they both may have just happened at the same time for me. It's been almost 10 years since I had to deal with this. I'm trying to approach my sys admins with delicacy as perhaps this is a limitation with Linux and not my admins.

It's very frustrating to have people pointing fingers and not working together to fix this. I gotta have something for my admins to look at if it is Linux.

I guess I'll have to do more research on linux.

erin