Hi Jon, It is important that you have proper exception handling for all your API calls, as there is always a possibility of them failing (otherwise we wouldn't document those methods as throwing an exception). In the catch block you should usually fallback or retry gracefully: for memcache it makes senses to fallback on datastore (more latency, but more reliable).
In addition you can use the capabilities API to proactively query if a given API is available, this is described in details by Nick Johnson in the following blog post: http://blog.notdot.net/2010/03/Handling-downtime-The-capabilities-API-and-testing Hope that helps. On Thu, Oct 27, 2011 at 8:28 AM, jon <[email protected]> wrote: > How did you fix/get around this problem? > > It was pointed out to me that the MemcacheService by default should > *NOT* throw any exception, therefore what I was seeing is a bug. > > Can anyone from Google confirm if this is the case? I'm using 1.5.4. > > On Oct 26, 9:32 am, James Broberg <[email protected]> wrote: >> Fair enough. At least you got a memcache exception :) In our case >> performance just deteriorated and eventually it timed out. >> >> On 26 October 2011 00:17, jon <[email protected]> wrote: >> >> >> >> >> >> >> >> > Thanks James for pointing them out. They're not entirely identical in >> > that the symptom is different (i.e. the exception I got is different). >> > However there's a common pattern whereby an app seems to be assigned a >> > memcache "service provider" and if this provider misbehaves the app >> > will be stuck with it instead of getting reassigned a new, healthy >> > replacement. >> >> > On Oct 25, 11:26 pm, James Broberg <[email protected]> wrote: >> >> Sounds familiar: >> >> >>http://code.google.com/p/googleappengine/issues/detail?id=5790http://... >> >> >> On 25 October 2011 20:16, jon <[email protected]> wrote: >> >> >> > Memcache for our app is back now. >> >> >> > According to the log, memcache write operations started throwing >> >> > com.google.appengine.api.memcache.MemcacheServiceException at 17:49 >> >> > (Melbourne >> >> > time) and stopped at 18:56. In other words memcache was unavailable >> >> > for over 1 >> >> > hour. >> >> >> > We use memcache heavily, so our site would've been down for that long >> >> > if we >> >> > hadn't stepped in to turn off all uses of memcache. >> >> >> > Question for Google: is there an affinity between an app and it's >> >> > memcache >> >> > service provider? How can memcache consistently error out for the same >> >> > application for that long? >> >> >> > On Oct 25, 6:29 pm, jon <[email protected]> wrote: >> >> >> Hi, >> >> >> >> Writing to memcache is down for one of our apps, other apps are OK. >> >> >> >> The error message says: >> >> >> java.lang.RuntimeException: >> >> >> com.google.appengine.api.memcache.MemcacheServiceException: Memcache >> >> >> put: Set failed to set 20 keys >> >> >> >> The affected app id: thecrowdvoice >> >> >> >> Could someone from Google urgently take a look please? >> >> >> >> Thanks in advance, >> >> >> Jon >> >> >> > -- >> >> > You received this message because you are subscribed to the Google >> >> > Groups "Google App Engine" group. >> >> > To post to this group, send email to [email protected]. >> >> > To unsubscribe from this group, send email to >> >> > [email protected]. >> >> > For more options, visit this group >> >> > athttp://groups.google.com/group/google-appengine?hl=en. >> >> > -- >> > You received this message because you are subscribed to the Google Groups >> > "Google App Engine" group. >> > To post to this group, send email to [email protected]. >> > To unsubscribe from this group, send email to >> > [email protected]. >> > For more options, visit this group >> > athttp://groups.google.com/group/google-appengine?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/google-appengine?hl=en. > > -- Johan Euphrosine (proppy) Developer Programs Engineer Google Developer Relations -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
