Memcache connection errors

Reinis Rozitis roze at
Wed May 24 21:26:37 UTC 2006

We sometime (quite rarely) experience the same situation / "Unknown error 
(0)" issues (on a gigabit network with all the openfiles limits maxed out) 
though we are unable to track down any network problems.

The workaround we use is just to doublecheck the connection and on failure 
make a second attempt:

$mc = new Memcache;
if (!$mc->connect('',11212)) { $mc->connect('',11212); }


----- Original Message ----- 
From: Kamran Nisar
To: memcached at
Sent: Tuesday, May 23, 2006 4:52 PM
Subject: Memcache connection errors

hey alll...
we are having a weird problem with memcache.. descriptions below.

the problem:
we shifted our hosting company, and ever since we got at the new one.. we 
have been getting random connection error to memcache...
we've run various packets transfers during the memcache test to see if a 
similar error is encountered there.. but the the problem seems to occur with 
memcache only..

the memcached lies on anoher machine, and the hits are generated using ab, 
when using anything above total of 1000 and concurrent of 150 connections.. 
we start getting random errors.. the errors are mentioned below

PHP Warning:  Memcache::pconnect() [<a 
href='function.pconnect'>function.pconnect</a>]: Can't connect to, Unknown error (0)
PHP Warning:  Memcache::pconnect() [<a href=' 
function.pconnect'>function.pconnect</a>]: Can't connect to, 
Connection timed out (110)

increased the port range to accomadate over 64K connections, recompiled the 
kernel to accomodate TIME_WAIT to 2 secs, tried setting up memcached on the 
same machine, remote machine.. but the errorr keeps randonmly showing up...

we are currently using 100Mbps ethernet cards , while previously we had 
gigabit ethernet on managed switches.. and we have also swtiched from intel 
to 64 bit AMD

any suggestions/ides for debugging or reasons as to why the random connect 
error comes up...
M Kamran Nisar, 

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