Memcached works well, then hangs

[Chris Bolt]

>>Have you tried disabling persistent connections in your memcache
>>client? I ran into that problem as well a while back, and disabling
>>persistent connections fixed it. I think it may have been some sort of
>>PHP bug, but I couldn't track it down.
> 
> I could help you to track it down if you give me some more info about it. 

I was using the cytherianage client, not the PECL one. I'm going to try 
switching to the PECL client in a few days, now that the one feature I 
was waiting for has been added (fetching multiple keys at once, thanks 
for adding that btw).

It's pretty tricky to find the problem. I'm pretty sure the bug is in 
PHP because it only happens to one web server in our cluster at a time, 
and when I strace an httpd process, it's hanging while waiting on data 
from a single memcache server (all httpd processes appear to hang on the 
same server). Maybe some script gets interrupted and leaves a persistent 
connection in the wrong state? I really don't have much of an idea, 
except that the memcache server itself was fine, since all of the other 
web servers were communicating with it fine, and since disabling 
persistent connections made the problem go away.