Wednesday, July 23

Geek

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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1 When Glenn linked to me last week it didn't seem to cause mee.nu any problems that I noticed. Good job on that.

Posted by: Steven Den Beste at Wednesday, July 23 2008 03:01 AM (+rSRq)

2 AVG stopped LinkScanner prescanning search results in an update issued on July 8th. Maybe you need to update?

Posted by: Pat Bitton at Thursday, July 31 2008 05:48 AM (dLNuu)

3

Pat, I think you're a bit confused here. The problem isn't that Pixy's copy of LinkScanner is doing those evil things.

It's that the copies used by hundreds of random visitors are doing those evil things. An upgrade by Pixy of his copy of LinkScanner (even assuming he even has one, which I doubt) would have no effect on that.

Posted by: Steven Den Beste at Thursday, July 31 2008 07:00 AM (+rSRq)

4 Pat's been going around posting that (and missing the point) anywhere there's been a complaint. (Like here.) Wonder if his IP matches AVG’s?

Posted by: Old Grouch at Friday, August 01 2008 09:29 AM (8m7sz)

5 Yes I got a comment from "Pat" too.  Now I realize it was actually someone trolling. 

I've been so busy lately I haven't had time to "get out" much to other blogs.  (a sucky situation I hope will change soon... but with my luck probably not).   So I didn't realize our little friend had hit lots of us with the same idiot message. 

Posted by: Teresa at Friday, August 01 2008 02:00 PM (mMa3+)

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