Privvmpages Red Zone (Apache MPM Worker)

So, I always feel compelled to blog about issues I encounter with programming or sysadmin when they stump me for days — hopefully saving someone else the headache if they take the time to Google (with the correct terms, which is always key).

So I’ve been configuring a VPS for the new site that will be launching soon, and I kept running into issues with privvmpages in Parallels Power Panel (Virtuozzo). Virtuozzo would report privvmpages in the red zone — 370,614 pages of 393,216. Yet, oomguarpages would be completely fine, normal and low. I could not figure out what the deal was, and services were getting killed left and right.

The issue? Well, I decided to compile Apache 2.2 as MPM Worker after some reading about how it was more efficient and generally more awesome then prefork. I guess that maybe true, but what they didn’t say (and a quick Google search now tells me) is that worker goobles up a lot of virtual memory. As in, over 230 MB+ per process without anything going on. Privvmpages takes a best guess at calculating memory usage (including virtual memory), so I was quickly exceeding the 1.5 GBs hard limit my host had set.

So now I’ve recompiled apache as prefork and all is right in the world again. No more errors, no more services dying. And only 8 days lost. :-p

So be warned! Don’t compile apache as MPM Worker on a VPS. You’ll need to compile as prefork instead.

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