1.2.4 problems with high concurrency, getting off by a request

[dormando]

First I've heard of this... I'm sure we'd love to have some data and
maybe something to help reproduce this.

-Dormando

Kevin Watt wrote:
> Hi,
> 
> I haven't yet generated a test case that can duplicate this, but thought
> I'd announce my initial findings in case anyone else has been having
> problems with this, or have ideas about what exactly the problem might
> be.  Rolling back to 1.2.2 fixed the problem for me.
> 
> I run a fairly large site, 5 rails processes connect to memcache and
> set/get a lot of cached data.  Some of it is compressed, and some of it
> is up to 40k.  Eric Hodel's memcache_client (which I ended up hacking to
> add more error checking and debug printing).
> 
> I've experienced problems with it getting out of sync, for example
> 
> 1) When I would be expecting an "END\r\n", it would send value data from
> another request made awhile ago (or possibly by another process).
> 2) When I would request key "ns:bans" it would reply "value
> another_key".  It would stay "behind" by a key for the entire request,
> always returning the key requested 2x ago, not the most recent request.
> 3) The whole thing would hang because socket.gets or socket.puts
> wouldn't return
> 
> 
> I ended up adding a lot of error-checking to make sure the key the value
> being returned for was correct, then closing the connection if it was
> not.  As well as returning when missing END, etc.
> 
> Unfortunately, rafb.net removed my pastes of errors because I
> procrastinated too long before sending this report.  Hopefully the
> symptoms above are enough to help someone who perhaps knows the
> internals to track down what the problem might be.
> 
> As I said, rolling back to 1.2.2 fixed the problem.  Thanks for an
> overall great project! :)
> 
> Thanks,
> Kevin Watt
> "After all, what is your hosts' purpose in having a party? Surely not
> for you to enjoy yourself; if that were their sole purpose, they'd have
> simply sent champagne and women over to your place by taxi." - P. J.
> O'Rourke
>