I've recently noticed infrequent problems with MySQL not being able to start a new thread. I was curious because I'm usually nowhere near my numproc or memory limits. Looking at the QoS alerts in the Virtuozzo CP, I apparently often trip over the kmemsize warning threshold. All the documentation I can find indicates that this kernel memory is just for the kernel's process/thread table. I wouldn't have guessed that anything in my configuration launched an inordinately large number of processes or threads, nor does the QoS alerts log indicate any numproc or memory problems. Pretty standard software -- Apache 2.2 (prefork MPM), MySQL 4.1. It's really only been a problem in the past week or so, not particularly coincidental with any big changes to any of my software versions. Anyone have any thoughts?