I can also add that a new deployment does not clear memcache (it was an issue for me since it was hiding all changes in my upload). Memcache on the other hand can expire in any moment, so you must be ready to accept some data loss if you don't want to back it using the dataastore.
Regards Lorenzo On Jul 14, 6:08 pm, Ingo Jaeckel <[email protected]> wrote: > aah alright. thanks Don for the clarification! > > kind regards, > ingo > > 2010/7/14 Don Schwarz <[email protected]>: > > > That is correct. You can not maintain state within the JVM and expect to > > get any long-term persistence or coherency. > > > You should use either memcache (which provides coherency) or the datastore > > (which provides both). > > > On Wed, Jul 14, 2010 at 3:38 PM, Ingo Jaeckel <[email protected]> > > wrote: > > >> hello everyone, > > >> i just had a look into the documentation > >>http://code.google.com/intl/de-DE/appengine/docs/java/runtime.html > > >> "App Engine uses multiple web servers to run your application, and > >> automatically adjusts the number of servers it is using to handle > >> requests reliably. A given request may be routed to any server, and it > >> may not be the same server that handled a previous request from the > >> same user." > > >> does this mean that there are n jvms on n servers running my > >> application. thus if i want to collect profiling information about my > >> server code i will always have to persist it in the db. it would not > >> be sufficient just to hold it within the app (thus within the jvm). > >> because i will have different application stats across the different > >> servers running my application in parallel and independently.. > > >> can anyone confirm this claim? > > >> kind regards, > >> ingo > > >> 2010/7/13 ingo <[email protected]>: > >> > hello everyone, > > >> > i want to collect some performance figures of my app on the server > >> > side. but i do not want to persist them in the database, i only want > >> > to collect them by changing the state of some class (i.e. changing > >> > class members like number of requests, number of method calls, etc). i > >> > want to read these values on the client side and display them in an > >> > administration panel (or a profiler-like ui). > > >> > but currently i think the application state is at least lost after > >> > each new deployment. is this the only time the state is resetted? does > >> > a jvm holding my application state run all the time between each > >> > deployment? > > >> > i have the same question regarding static members. i use singletons or > >> > static variables on server side to make sure they are constructed only > >> > once whenever their construction is expensive. so i want to make sure > >> > that the jvm holding the instances is running for a very long time to > >> > avoid reconstruction of them. however, it feels like the jvm is > >> > restarted relatively often (due to very low load on my app maybe) and > >> > thus the singletons are recreated during the jvm startup. > > >> > kind regards, > >> > ingo > > >> > -- > >> > You received this message because you are subscribed to the Google > >> > Groups "Google App Engine for Java" 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-java?hl=en. > > >> -- > >> You received this message because you are subscribed to the Google Groups > >> "Google App Engine for Java" 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-java?hl=en. > > > -- > > You received this message because you are subscribed to the Google Groups > > "Google App Engine for Java" 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-java?hl=en. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" 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-java?hl=en.
