If silent failure on write is to be acceptable, we need a way to make sure following requests do not read session from memcache, as it could return an old value. I am unaware of any way to accomplish this reliably without hitting the datastore, at which point you might as well not have the session in memcache at all.
One possible alternative is to replace the entire session with storing encrypted data in a cookie, though this only works for smaller amounts of data as the maximum size for an entire cookie is generally said to be 4095 bytes. Just my 2 cents. Joakim On Wednesday, July 4, 2012 11:38:34 PM UTC+2, Per wrote: > > > When using sessions, these are (also) stored in memcache by GAE. > Unfortunately, it seems like any memcache hiccup can crash the process, > turning an otherwise fine page into a 500 page on the way out. > > To me that looks like a design flaw. After all, Memcache is optional, and > its expected to be unavailable or breaking every now and then. As of 1.6 > you can even provide a policy to silently ignore memcache errors inside > your application. We're using > setErrorHandler(ErrorHandlers.getConsistentLogAndContinue(Level.SEVERE)) > with Objectify just fine, but it doesn't seem to have any effect on the > Session-Save process. This seems to be entirely outside our control. > > These errors are really annoying some of our clients. Is there maybe some > kind of other error handler I'm missing? > > Here's the stracktrace for reference: > > > com.google.appengine.api.memcache.MemcacheServiceException: Memcache put: > Error setting single item (_ahsOH7nik8bCRTbIXblKurKQQ) > at > com.google.appengine.api.memcache.AsyncMemcacheServiceImpl$7.transform(AsyncMemcacheServiceImpl.java:426) > at > com.google.appengine.api.memcache.AsyncMemcacheServiceImpl$7.transform(AsyncMemcacheServiceImpl.java:418) > at > com.google.appengine.api.memcache.MemcacheServiceApiHelper$RpcResponseHandler.convertResponse(MemcacheServiceApiHelper.java:60) > at > com.google.appengine.api.memcache.MemcacheServiceApiHelper$1.wrap(MemcacheServiceApiHelper.java:112) > at > com.google.appengine.api.memcache.MemcacheServiceApiHelper$1.wrap(MemcacheServiceApiHelper.java:105) > at > com.google.appengine.api.utils.FutureWrapper.wrapAndCache(FutureWrapper.java:57) > at > com.google.appengine.api.utils.FutureWrapper.get(FutureWrapper.java:98) > at > com.google.appengine.api.utils.FutureWrapper.get(FutureWrapper.java:90) > at > com.google.appengine.api.memcache.MemcacheServiceImpl.quietGet(MemcacheServiceImpl.java:28) > at > com.google.appengine.api.memcache.MemcacheServiceImpl.put(MemcacheServiceImpl.java:81) > at > com.google.apphosting.runtime.jetty.MemcacheSessionStore.saveSession(MemcacheSessionStore.java:39) > at > com.google.apphosting.runtime.jetty.SessionManager$AppEngineSession.save(SessionManager.java:164) > at > com.google.apphosting.runtime.jetty.SaveSessionFilter.doFilter(SaveSessionFilter.java:41) > at > org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) > at > com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43) > at > org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157) > at > org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388) > at > org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216) > at > org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182) > at > org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765) > at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418) > at > com.google.apphosting.runtime.jetty.AppVersionHandlerMap.handle(AppVersionHandlerMap.java:249) > at > org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152) > at org.mortbay.jetty.Server.handle(Server.java:326) > at > org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542) > at > org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:923) > at > com.google.apphosting.runtime.jetty.RpcRequestParser.parseAvailable(RpcRequestParser.java:76) > at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404) > at > com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:135) > at > com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:477) > at > com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:449) > at > com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:455) > at com.google.tracing.TraceContext.runInContext(TraceContext.java:695) > at > com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:333) > at > com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:325) > at > com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:453) > at > com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:251) > at java.lang.Thread.run(Thread.java:679) > > > And here's the code I tried, but which didn't help: > > MemcacheService service = > MemcacheServiceFactory.getMemcacheService(); > service.setErrorHandler(new > LogAndContinueErrorHandler(Level.SEVERE)); > > Any help would be appreciated! > > Kind regards, > Per -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. 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