mysql pconnect voes

Im managing a really crowded webservers. We have article system implemented in php and backend db is mysql (not my first choise but hey, it does the job) Few version numbers: PHP: 4.0.6 (Self compiled, w/ gcc in solaris8) Mysql: 3.23.24 (Self compiled, w/ gcc in solaris8, ok, not the latest stable but i dont think this is the real problem) Apache: 1.3.22 (Self compiled w/ no other 3rd party modules besides php) Our code uses pconnects throuout the whole site. Website is ran from 6 different sparc solaris boxes and one db box is serving them all. This mysql has connection limit in 750 and all apache servers have following three lines in their php.ini: mysql.allow_persistent=On mysql.max_persistent=50 mysql.max_links=70 Afaik (mysql.max_links - mysql.max_persistent) is how many nonpersistent connection i can have (in this case, 20 per server). And i have 50 persistent. So, i have 6 servers with 50 persistent connections and all pconnects are to same db with same account so there should be available connections in the pool. BUT. After 5 minutes or less (depending on the time/load) all connections hang because php has used *all* available connections in mysql server (which is 750). I cant image how this is possible. I have 70 connections per server, 6 servers, thats 420 max connectios, that should leave with with 330 spare ones but now. Everything is used up. Even if i would have 50+70 connections (120*6=720) per server, i would still have 30 spare ... So, only solution for me is to set mysql connection timeouts to really low (20 seconds, when default value is 8 hours). And this leads me to *huge* error logs. For example, i just deleted few months old mysql log which was over 2 gigs. I have few ideas. Are these limits in php, per process or per whole process tree ? Sounds to me that they are per process or pconnect still has really nasty bugs in it.