Detuned For Speed

An Instalanche at mu.nu is nothing new; we've coped with many a 'lanche over the years.

But an Instalanche combined with AVG 8's accidental DDoS and CPanel's screwed up Apache builder was too much for us.  The server was coping just fine, but you had to stand in line waiting for a connection.

The cure?  Smack keepalive over the head, hard.  What was happening was that random Instapundit reader comes along and sees link to Protein Wisdom.  Follows link.  AVG 8 says Aha!  A web page!  Potential danger!  And follows twenty links from that page in parallel.

And, more often than not, grabs 20 links from the monthly archive listing, so it hits Protein Wisdom 20 more times.  And then the keepalive timeout sits there holding the connection open, so that a single visitor to the blog is using up 300MB of precious server RAM.

I tried just increasing the number of available threads, but Apache has now been compiled with a hard limit of 256.  This wasn't true before; it's a new twist the friendly idiots at CPanel seem to have thrown into the mix.

So, instead, I aggressively de-optomised keepalive.  The timeout is now 2 seconds, and there's a maximum of 5 requests before it drops the connection.  That seems to have brought us sufficient breathing space until I can get some sites spun off to Sakura.

Posted by: Pixy Misa at 12:48 AM | Comments (5) | Add Comment | Trackbacks (Suck)
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