problem when multiple processing

I've found a problem in PEAR when trying to cache the same function in the same time (2 processes running in the same time the Cache_Function->call function): - two (2) cache files are created, that are almost identical, except for the id from the beginning of the file). - the function cached has no parameters - the id created in the pear/Cache/Function.php with the $id = md5(serialize($arguments)); is the same, and yet it creates another cache file that differs with the previous one (or the one created simultaneously) with the last number from the id written in the cache file. - the problem is that, after many runs, the cache becomes huge. Doesn't PEAR erases old or expired functions ? Can anyone tell me if you've found a solution to this problem ? Thanks in advance, Lucian COZMA lcozma@interakt.ro