Jeff, you are right the default handler is supposed to handle both
DeserializationError and ServiceError:
http://code.google.com/p/googleappengine/source/browse/trunk/java/src/main/com/google/appengine/api/memcache/LogAndContinueErrorHandler.java

Jon did you change the default memcache error handler ?

On Thu, Oct 27, 2011 at 1:37 PM, Jeff Schnitzer <[email protected]> wrote:
> Are you saying that we should not expect the
> MemcacheService.set/getErrorHandler(), with its default value of
> LogAndContinueErrorHandler, to do what it says?  I expect memcacheservice to
> fail silently.
> Is it possible that the error handler showed up in 1.5.5?  The OP mentioned
> in another thread that he is running on 1.5.4.
> Jeff
> On Wed, Oct 26, 2011 at 5:12 PM, Johan Euphrosine <[email protected]> wrote:
>>
>> 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
>> >>
>> >> >> > --
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>>
>> --
>> Johan Euphrosine (proppy)
>> Developer Programs Engineer
>> Google Developer Relations
>>
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-- 
Johan Euphrosine (proppy)
Developer Programs Engineer
Google Developer Relations

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