Slab Class 1 disappearing sometimes, unable to set values less than 35 bytes size

[GoogleCodeExporter]

Hello,

On 5 of our 10 servers memcached farm we hit a strange bug:

We found that faulty servers did not let store key/value pair when value size 
is longer than 35 bytes:

set pouet 0 0 1
SERVER_ERROR out of memory storing object
set pouet 0 0 34
SERVER_ERROR out of memory storing object
set pouet 0 0 35   
...................................
STORED

While investigating, we found out that those faulty servers did not have any 
Class 1 Slab at all:

stats slabs
STAT 2:chunk_size 120
STAT 2:chunks_per_page 8738
STAT 2:total_pages 234
STAT 2:total_chunks 2044692
STAT 2:used_chunks 2044692
STAT 2:free_chunks 0
STAT 2:free_chunks_end 0
STAT 2:mem_requested 233580169
STAT 2:get_hits 498960865
STAT 2:cmd_set 6159027
STAT 2:delete_hits 0
STAT 2:incr_hits 34523
STAT 2:decr_hits 0
STAT 2:cas_hits 0
STAT 2:cas_badval 0

Of course, this leads to the absence of data about outofmemory errors on slab 
class 1, so counters are all set to zero, and there is no counter for slab 
class 1.

What steps will reproduce the problem?

memcached 1.4.4 @ Ubuntu hardy / kernel 2.6.24-22-server
Command Line: /usr/bin/memcached -m 20000 -p 11211 -u memcached -c 16384 -L -C

Wait some time, reach the maximum memory usage (20G), and it MIGHT happen on 
your server :)

What would you advise to do to gather more data ?

Shouldn't memcached try to allocate key/value pairs in the next slab class at 
least ?

Thanks !

Original issue reported on code.google.com by sameh.gh...@gmail.com on 18 Mar 2011 at 3:58

[GoogleCodeExporter]

Please start memcached without -L parameter. Performance may decrease but you 
will not experience this isue. Hopefully this will be resolved with the next 
release.

Regards,
Abid S. Atilay

Original comment by abid.ati...@gmail.com on 29 Mar 2011 at 10:51

[GoogleCodeExporter]

Great !

Could using a newer kernel help ?

Thanks a lot,

Cheers,

Sameh.

Original comment by sameh.gh...@gmail.com on 29 Mar 2011 at 5:36

[GoogleCodeExporter]

should be fixed with 1.4.14. closing.

Original comment by dorma...@rydia.net on 30 Jul 2012 at 9:20

• Changed state: Fixed