On 17 Jul 2012, at 15:33, Yiftach Shoolman wrote:
Re #2 - when more objects are stored in the cache, the hit ratio
should be
higher--> the application might run faster, i.e. with less DB
accesses.
no relation here, I was really mentioning bare set() calls timing,
regardless of anything else.
Anyway, it sounds to me more related to slabs allocation, as only
reset
solves it (not flush) if I understood u well.
all the slabs are already allocated, with a moderate rate of evictions.
so it's not slab
allocation either, it's just one key now and then, regardless (it seems)
of the key
itself or the size of the object.
Does it happen on any object size or on specific object size range ?
anything, really. puzzling, hey?
thanks!
On Tue, Jul 17, 2012 at 4:04 PM, David Morel
<[email protected]>wrote:
On Tuesday, July 17, 2012 12:26:16 PM UTC+2, Yiftach wrote:
Few things that may help understanding your problem:
1. What is the status of your slabs allocation, is there enough room
to
all slabes ?
This happens when the memory gets close to full. however there is not
a
large number of evictions.
I would expect evictions to be made whenever needed, but not the
process
of making room for 1 object to take half a second.
2. Do you see increase in the requests rate when your Memcached
memory is
becoming full with objects ?
I don't think so, why would that be the case, it's application
dependent,
not server, right?
3. How many threads are configured ?
the default 4
On Tue, Jul 17, 2012 at 1:11 PM, David Morel
<[email protected]>wrote:
hi memcached users/devvers,
I'm seeing occasional slowdowns (tens of milliseconds) in setting
some
keys on some big servers (80GB RAM allocated to memcached) which
contain
a large number of keys (many millions). The current version I use
is
1.4.6 on RH6.
The thing is once I bounce the service (restart, not flush_all),
everything becomes fine again. So could a large number of keys be
the
source of the issue (some memory allocation slowdown or something)?
I don't see that many evictions on the box, and anyway, evicting an
object to make room for another shouldn't take long, should it? Is
there
a remote possibility the large number of keys is at fault and
splitting
the daemons, like 2 or more instances per box, would fix it? Or is
that
a known issue fixed in a later release?
Thanks for any insight.
David Morel
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Yiftach Shoolman
+972-54-7634621
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Yiftach Shoolman
+972-54-7634621
David Morel
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