Hit Erik, >From your stack trace, I think you are seeing something else. Have you got an explicit serialVersionUID set in the com.WikiHop.jdo.Pi class (your key is OK I think) that you are putting into Memcache? And if so has it changed at some point? It looks like you may be either trying to read out a different class entirely than was inserted into the cache, or have changed or added the serialVersionUID in the value class since an entry was inserted and it is now stale. serialVersionUID is a way of identifying a class (or "version" of a class) to the java serialization framework - if you change it you are telling it that it is effectively no longer compatible for serialization with previous instances, even if you have change nothing else in the class. So it's a good idea to set it early, and never change it for a class unless you have a good reason to invalidate older serialized entries.
I'm not having any problems reading values out of the cache. The problem I'm seeing is that the entire entry can only be found if it was inserted by the same JVM (or "instance') that inserted it. A scoping problem where it appears to be less global than it should be. You may want to start a separate thread on your issue if you are still seeing it and the above doesn't shed any light on it. Thanks, Tom On Dec 17, 4:11 am, Erik <erik.e.wil...@gmail.com> wrote: > Missed some more errors: > > Caused by: java.io.InvalidClassException: com.WikiHop.jdo.Pi; local > class incompatible: stream classdesc serialVersionUID = > -6007756724690804603, local class serialVersionUID = -1398789866 > at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:579) > at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java: > 1600) > at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java: > 1513) > at > java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java: > 1749) > at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1346) > at java.io.ObjectInputStream.readObject(ObjectInputStream.java:368) > at > com.google.appengine.api.memcache.MemcacheSerialization.deserialize(MemcacheSerialization.java: > 163) > at > com.google.appengine.api.memcache.MemcacheServiceImpl.get(MemcacheServiceImpl.java: > 283) > ... 43 more > > On Dec 17, 3:56 am, Erik <erik.e.wil...@gmail.com> wrote: > > > Not sure if it is related, but I was getting some interesting memcache > > errors that I had to work around: > > > javax.servlet.ServletContext log: Exception while dispatching incoming > > RPC call > > com.google.gwt.user.server.rpc.UnexpectedException: Service method > > 'public abstract java.lang.String > > com.WikiHop.client.SearchPath.find(java.lang.String,java.lang.String) > > throws java.lang.IllegalArgumentException' threw an unexpected > > exception: com.google.appengine.api.memcache.InvalidValueException: IO > > exception parsing value of '3434143' > > at > > com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java: > > 378) > > ... > > Caused by: com.google.appengine.api.memcache.InvalidValueException: IO > > exception parsing value of '3434143' > > at > > com.google.appengine.api.memcache.MemcacheServiceImpl.get(MemcacheServiceImpl.java: > > 289) > > at > > com.google.appengine.api.memcache.jsr107cache.GCache.get(GCache.java: > > 166) > > > On Dec 16, 2:53 pm, Tom Phillips <tphill0...@gmail.com> wrote: > > > > Certainly Ikai, > > > > Firstly, some of my logs (url and classes slightly modified to hide > > > some app details) that show how only the same instance picks up the > > > entry. I'm determining and logging the instance using a UUID that I > > > assign to a static class variable. The key for the cache lookup is > > > passed in as a request query parameter to the followup requests. > > > > Here are two runs of the code to follow. In each, the bottom log is > > > the cache entry being added. The next two are subsequent requests that > > > both look for the entry. The entry is only found when then instance > > > matches, regardless of which follow-up request. > > > > This first run shows how the bottom instance is different from the one > > > that services both followup requests. So they don't find the entry: > > > > 50.16.21.20 - - [16/Dec/2010:11:19:40 -0800] "GET /processg?key=619001 > > > W 12-16 11:19AM 40.373 com.mycode.CallProcessGatherServlet doGet: > > > LOOKING IN CACHE on Instance: b7c866f2-d74b-45df-9993-1d2c4705d3d1 > > > W 12-16 11:19AM 40.373 com.mycode.CallProcessGatherServlet doGet: > > > Message NOT found in cache for 619001 - building > > > > 50.16.21.20 - - [16/Dec/2010:11:19:35 -0800] "POST /startreminder? > > > key=619001&pname=Optimal+Physio+Dev&atime=Friday+December+17%2C > > > +2%3A18+PM&rlang=en&rvoice=woman > > > W 12-16 11:19AM 33.173 com.mycode.CallMLServlet doGet: LOOKING IN > > > CACHE on Instance: b7c866f2-d74b-45df-9993-1d2c4705d3d1 > > > W 12-16 11:19AM 33.173 com.mycode.CallMLServlet doGet: Message NOT > > > found in cache for 619001 - building > > > > 0.1.0.2 - - [16/Dec/2010:11:19:08 -0800] "POST /tasks/voicereminder > > > HTTP/1.1" 200 105 "http://cliniconexdev.appspot.com/cron/ > > > processreminders?state=new" > > > W 12-16 11:19AM 08.581 com.mycode.CallPhoneAdapter doSend: CACHING > > > message from instance: e4d5452e-c744-4333-b1d4-38eb55f97445 > > > W 12-16 11:19AM 08.585 com.mycode.CallPhoneAdapter doSend: Adding to > > > cache with key:619001 > > > W 12-16 11:19AM 08.604 com.mycode.CallPhoneAdapter doSend: > > > Successfully cached reminder 619001 > > > > In this second run, the first followup request hits the same instance > > > that added it, and finds it. The second isn't so lucky, hitting a > > > different instance > > > > 184.73.13.122 - - [16/Dec/2010:11:22:39 -0800] "GET /processg? > > > key=620001 > > > W 12-16 11:22AM 38.782 com.mycode.CallProcessGatherServlet doGet: > > > LOOKING IN CACHE on Instance: ff6ef71c-a017-4316-aa81-e77db741702b > > > W 12-16 11:22AM 38.782 com.mycode.CallProcessGatherServlet doGet: > > > Message NOT found in cache for 620001 - building > > > > 204.236.222.67 - - [16/Dec/2010:11:22:28 -0800] "POST /startreminder? > > > key=620001&pname=Optimal+Physio+Dev&atime=Friday+December+17%2C > > > +2%3A18+PM&rlang=en&rvoice=woman HTTP/1.1" 200 683 - > > > "CallProxy/0.7,gzip(gfe)" "cliniconexdev.appspot.com" ms=24 cpu_ms=23 > > > api_cpu_ms=0 cpm_usd=0.000805 > > > W 12-16 11:22AM 28.127 com.mycode.CallMLServlet doGet: LOOKING IN > > > CACHE on Instance: b7c866f2-d74b-45df-9993-1d2c4705d3d1 > > > W 12-16 11:22AM 28.134 com.mycode.CallMLServlet doGet: Message for > > > entry 620001 FOUND in cache - using > > > > 0.1.0.2 - - [16/Dec/2010:11:22:06 -0800] "POST /tasks/voicereminder > > > HTTP/1.1" 200 105 "http://cliniconexdev.appspot.com/cron/ > > > processreminders?state=new" "AppEngine-Google; > > > (+http://code.google.com/appengine)" "cliniconexdev.appspot.com" > > > ms=506 cpu_ms=1664 api_cpu_ms=941 cpm_usd=0.046287 queue_name=reminder- > > > queue task_name=17196018701084092971 > > > W 12-16 11:22AM 05.964 com.mycode.CallPhoneAdapter doSend: CACHING > > > message from instance: b7c866f2-d74b-45df-9993-1d2c4705d3d1 > > > W 12-16 11:22AM 05.965 com.mycode.CallPhoneAdapter doSend: Adding to > > > cache with key:620001 > > > W 12-16 11:22AM 05.984 com.mycode.CallPhoneAdapter doSend: > > > Successfully cached reminder 620001 > > > > Here is the code that creates the cache (if required) and adds the > > > entry in the first request: > > > Cache cache = null; > > > > log.warning("CACHING message from instance: " + jvmId); > > > > try { > > > cache = CacheManager.getInstance().getCache("cache_reminderVoice"); > > > } catch (final Exception e) { > > > log.fine("Cache cache_reminderVoice not yet created"); > > > > } > > > > if (cache == null) { > > > try { > > > cache = CacheManager.getInstance().getCacheFactory() > > > .createCache(Collections.emptyMap()); > > > CacheManager.getInstance().registerCache("cache_reminderVoice", > > > cache); > > > } catch (final CacheException e) { > > > log.warning("Could not create/register cache > > > cache_reminderVoice: " > > > + e.getMessage()); > > > } > > > > } > > > > try { > > > // Put the value into the cache. > > > log.warning("Adding to cache with key:" + > > > reminder.getKeyId().toString()); > > > if (parts == null) { > > > log.warning("Hmmmm..parts was null"); > > > } > > > cache.put(reminder.getKeyId().toString(), parts); > > > > // Get the value from the cache just to test it is there > > > final CacheEntry entry = cache.getCacheEntry(reminder.getKeyId() > > > .toString()); > > > if (entry != null) { > > > log.warning("Successfully cached reminder " + > > > reminder.getKeyId()); > > > } else { > > > log.warning("Could not get cached voice message parts"); > > > } > > > } catch (final Exception e) { > > > log.warning("FAILED to cache voice message parts: " + > > > e.getMessage()); > > > } > > > > Here is the code (same in both request handlers) that retrieves the > > > entry from the cache: > > > > Cache cache = null; > > > > log.warning("LOOKING IN CACHE on Instance: " + > > > TwilioPhoneAdapter.jvmId); > > > > try { > > > cache = > > > CacheManager.getInstance().getCache("cache_reminderVoice"); > > > if (cache != null) { > > > parts = (VoiceParts) cache.get(key); > > > } > > > if (parts != null) { > > > log.warning("Message for entry " + key + " FOUND in cache - > > > using"); > > > } > > > } catch (final Exception e) { > > > log.warning("Cache cache_reminderVoice not yet created"); > > > } > > > > if (parts == null) { > > > log.warning("Message NOT found in cache for " + key + " - > > > building"); > > > parts = ...//Builds the parts up from scratch > > > } > > > > Thanks for checking it out Ikai. > > > Tom > > > > On Dec 16, 1:32 pm, "Ikai Lan (Google)" <ikai.l+gro...@google.com> > > > wrote: > > > > > This is definitely not a design intent. Can you post any code or > > > > reproduction steps? > > > > > -- > > > > Ikai Lan > > > > Developer Programs Engineer, Google App Engine > > > > Blogger:http://googleappengine.blogspot.com > > > > Reddit:http://www.reddit.com/r/appengine > > > > Twitter:http://twitter.com/app_engine > > > > > On Wed, Dec 15, 2010 at 7:42 PM, Tom Phillips <tphill0...@gmail.com> > > > > wrote: > > > > > I posted on this this in the java forum, but no traction there and I > > > > > suspect it's not java specific. > > > > > > Memcache entries seem to be being scoped to an instance, not global. > > > > > After a cache entry is made, it can be retrieved fine for any request > > > > > that goes to that same instance. Any request to one of the other > > > > > instances never finds the entry in the cache. > > > > > > Bug in Always On? Bug in 1.4.0? Design intent? > > > > > > Thanks, > > > > > Tom > > > > > > -- > > > > > You received this message because you are subscribed to the Google > > > > > Groups > > > > > "Google App Engine" group. > > > > > To post to this group, send email to > > > > > google-appeng...@googlegroups.com. > > > > > To unsubscribe from this group, send email to > > > > > google-appengine+unsubscr...@googlegroups.com<google-appengine%2bunsubscr...@googlegroups.com> > > > > > . > > > > > For > > ... > > read more » -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appeng...@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
