I am running MySQL 5 on a production Ubuntu 8.04 server. Two separate php based sites are served, both of which involve intensive mysql queries.
What I noticed is that when I request a page on the first site, which causes a 100% cpu load by mysql for 1 min., the login page of the second web site cannot even be served. It seems that mysql fully occupies the cpu, so that even non demanding tasks cannot be completed in the meantime. Is there a way to work around this situation? Where does the real reason of the problem lie?