"Set" and then "get" don't retrieve the stored value
kristian.hellquist at gmail.com
Tue Nov 14 17:20:35 UTC 2006
Here's the dump. The key to look for is
'65b05a7489ea704c5afb80fee7b029497a80beac'. As you can see I do a
"set" with response "STORED" followed by a delete which returns "NOT
FOUND". After that follows various calls that I think you can ignore.
Thanks for your help,
2006/11/14, Brad Fitzpatrick <brad at danga.com>:
> I'm coming into this late.
> Why would a "get" right after a "set" not work? This isn't a known issue,
> at least not to me.
> If you can reproduce this easily, send me a tcpdump pcap file of the
> traffic to your memcached.
> If you're using the loopback to a 127.0.0.1 memcached on port 11211, run
> # tcpdump -w forbrad.pcap -s 0 -i lo port 11211
> Then do your (minimal!) failing test, control-C the tcpdump, and email me
> the forbrad.pcap file.
> On Tue, 14 Nov 2006, Kristian Hellquist wrote:
> > The problem is that the the small window unfortunately seems to be
> > quite large for me. Do you have measure in time of how small the
> > window is?
> > Basically, I have some unit tests on a web application. The web
> > application relies on memcached heavily. Everything with memcached has
> > worked like a charm for us so far. We cache sql-finders in memcached
> > and invalidates the sql-finders when the model has changed.
> > In a specific use-case we dont want to update the state of the db
> > immediately. This data change *a lot*. So when the state of model
> > change we will cache the sql-finder in memcache directly and later on
> > we flush the change to the db. It is in this use-case that I have
> > experienced the "set" and "get" problem.
> > My unit-test successfully ran when I added a sleep call of 0.3 s
> > between each memcache-call :/ This is a lot. Is there a way of
> > configurate memcached so I experience greater performance?
> > I know that the test-environment doesnt mimick the user behavior of
> > the webapplication in real use. We use rails and the unit tests
> > doensn't involve the webserver at all. So in real life more delay will
> > be inserted between each "set" and "get" call. But, can I *trust*
> > memcache that data has been stored if I receive a "STORED" response?
> > Is just a matter of time before the value can be retrieved again? Or
> > is it bad usage of memcache to cache the sql-finders directly and
> > later on update the db?
> > Thanks for your reply,
> > Kristian Hellquist
> > 2006/11/14, Jehiah Czebotar <jehiah at gmail.com>:
> > > > Basically, yes. There is a small window where this can happen. There
> > > > have been numerous discussions about it on the list. Most people note
> > > > it with a set and then delete.
> > > >
> > >
> > > tif my memory serves me, the correct order is a delete, set, then a
> > > get all for the same key
> > >
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