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Date: Sat, 14 Feb 2009 23:13:29 +0100
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Subject: open_basedir performance issue, realpathcache vs. statcache
From: rmie@gmx.de (Roland Mieslinger)

Hello,

we're managing a shared hosting environment with about 600 virtual
servers. All content for the websites is stored on a NFS share.

We're suffering from a huge amount of lstat calls, and identified 
open_basedir as the reason for that. strace shows that each call
needs 40µs in average, this is due to NFS.

A lot of questions arises from that, but some answers are still missing.
Maybe I can get them here.

Did open_basedir rely on realpathcache? I haven't found a definitive
answer to that. We have changed realpath cache size, without any impact.
So I assume the answer is no.

>From what I understand realpathcache is different from statcache. So
using clearstatcache should not flush the realpathcache. Am I correct?

Thanks for you help

Roland