Hi Gayle,
Yes, the *request* times out during the API call. It's not the API
call itself that's timing out. But there is no effective difference to
your application if you're caught in this situation (as you pointed
out). I'd assume the first few calls you make to memcache during a
request actually return False and None. But later on in your request
handler, so much time has already passed that your API call gets
interrupted by the DeadlineExceededException for the entire request.
I think for now your best bet is to catch the runtime
DeadlineExceededException and immediately return with some kind of
error code. We're looking into the cause of the delayed memcache calls
on failure. They should be immediately failing instead of waiting up
to a second to return. That's the root cause of the issue here.
I'm sorry for the trouble this is causing for your application. We're
working right now to address this issue. Someone from the team will
follow up when everything has been resolved.
-Brett
On Nov 13, 9:57 am, Gayle Laakmann <[EMAIL PROTECTED]> wrote:
> It was timing out within memcache.get and memcache.set -
> consistently. If I understand you correctly - you're saying that
> memcache isn't technically timing out, on the grounds that it would
> complete if given enough time. But, the cache misses take SO much
> time that it consistently timeouts during the operations of
> memcache.get and memcache.set.
>
> Ok, sure, that may be the case. I'm afraid I don't really see the
> difference between that and timing out. Either way, memcache.get and
> memcache.set aren't exactly just "return false and letting your
> application proceed." The fact is they are causing timeouts.
>
> obj = memcache.get(cache_key)
> File "/base/data/home/apps/careercup/13.329261908074364999/memcache/
> __init__.py", line 362, in get
> self._make_sync_call('memcache', 'Get', request, response)
>
> File "/base/python_lib/versions/1/google/appengine/api/
> apiproxy_stub_map.py", line 46, in MakeSyncCall
> stub.MakeSyncCall(service, call, request, response)
> File "/base/python_lib/versions/1/google/appengine/runtime/
> apiproxy.py", line 245, in MakeSyncCall
>
> rpc.Wait()
> File "/base/python_lib/versions/1/google/appengine/runtime/
> apiproxy.py", line 161, in Wait
> rpc_completed = _apphosting_runtime___python__apiproxy.Wait(self)
>
> On Nov 13, 9:45 am, Brett <[EMAIL PROTECTED]> wrote:
>
> > Hi Gayle,
>
> > I'm sorry to hear you're seeing issues. It's important to note that
> > there are two types of DeadlineExceededErrors. One is defined in
> > apiproxy_errors.py. The other is in runtime/__init__.py:
>
> >http://code.google.com/p/googleappengine/source/browse/trunk/google/a...
>
> > The names are the same, which makes this confusing. The latter error
> > is raised when the request has been processing for too long (~10
> > seconds). Perhaps what's happening here is that the cache misses are
> > causing a lot of extra work to be done, causing your application to
> > hit this other deadline.
>
> > The traceback sent by Pratham confirms this behavior. More detail on
> > how to deal with this is here, in the section entitled "The Request
> > Timer":
>
> >http://code.google.com/appengine/docs/python/requestsandcgi.html
>
> > -Brett
>
> > On Nov 13, 9:29 am, Gayle Laakmann <[EMAIL PROTECTED]> wrote:
>
> > > Despite what the post at the link below says, memcache is actually
> > > timing out and throwing a DeadlineExceededError. Furthermore, it
> > > hardly seems accurate to say that our apps should continue serving
> > > normally. The quota limits are so ridiculously low that we CAN'T
> > > serve pages without caching.
>
> > >http://groups.google.com/group/google-appengine-downtime-notify/brows...
> > > We will be taking memcache offline tomorrow morning from 9-10am PST
> > > (GMT-8) for routine maintenance. Calls to the memcache API will *not*
> > > throw exceptions but will instead return false for set() calls and
> > > None for get() calls (just like any other cache miss.)
>
> > > Your app should continue serving normally during this period, and
> > > we'll keep you updated on our progress. "
>
> > > Additonally, I'd like to make two suggestions:
> > > 1. If you're going to take down memcache, wouldn't it make sense to
> > > remove the quota limits? It hardly seems fair to penalized for
> > > exceeding quota when caching is disabled.
>
> > > 2. If you have to take down our apps for an hour, can you pick
> > > something like 2am - 3am? I know you don't want to go to work at 2am,
> > > but it's not really ok to take down our apps for an hour during prime-
> > > time.
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