Strange memcached behavior on stress test

[Paul T]

Hi Steve,

> No this was 32bit linux with 6 GB of memory and the
> HUGEMEM kernel patch 

A bit 'unusual' configuration, no? 
64bit can be considered 'unusual' too.

> and a 1 GB memcache.
> 
> Did you find out why this happened?

No. 

> Did it go away and stay away after a restart?

Yes. 

> How long do you typically run your memcached without
> a restart?

We restart it daily. 

> This is a little worrisome, because our production
> boxes typically run 
> 300-500 days without a reboot.

Hey, make sure your keys have no spaces in them ;-)

$c = new Cache();

$key = "somekey";
$val = "value";
$c->set ( $key, $val );
$the_val = $c->get( $key );

print ("Value: $val TheValue: $the_val \n");

$key = "some key";
$val = "value1";
$c->set ( $key, $val );
$the_val = $c->get( $key );

print ("Value: $val TheValue: $the_val \n");

pault at somehost:~/repos/rd/trunk/cache> php -q
Cache.php
<7 new client connection
<7 set somekey 0 0 5
>7 STORED
<7 get somekey
>7 sending key somekey
>7 END
Value: value TheValue: value
<7 set some key 0 0 6
>7 CLIENT_ERROR bad command line format
<7 value1
>7 ERROR
<7 get some key
Error parsing memcached response
Value: value1 TheValue:
>7 END
<7 connection closed.


Rgds.Paul.

 
> -Steve
> 
> Paul T wrote:
> > 
> > Is it happening on 64bit linux by any chance?
> > 
> > We got the similiar trouble once - after running
> > memcached instance for 3 weeks in a row. 
> > 
> > Rgds.Paul.
> > 
> > --- Stephen Woodbridge <woodbri at swoodbridge.com>
> > wrote:
> > 
> >> Hi all,
> >>
> >> I asked a question in my email about the stress
> test
> >> script, but I think 
> >> it might have gotten lost in the other
> information I
> >> posted. So I'll ask 
> >> again.
> >>
> >> Running the stress test with multiple clients
> >> eventually starts to 
> >> generate a lot of failures. After pushing a large
> >> number of GB through 
> >> the cache (like 64 GB+, don't remember the exact
> >> number) we started 
> >> getting a lot for failures on the test clients,
> like
> >> one was failing 30% 
> >> and another failing 60% of its sets. Restarting
> the
> >> server cleared the 
> >> problem until we pushed a lot of data through the
> >> cache again.
> >>
> >> So what is going on? Is this the cache
> fragmentation
> >> problem? Is there a 
> >> fix for this problem? Other thoughts?
> >>
> >> Thanks,
> >>    -Steve
> >>
> > 
> > 
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> 


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