[appengine-java] Re: calling backend servlet from a corn job servlet
http://www.pdjamez.com/2011/05/google-app-engine-backends-part-deux/ On Oct 23, 5:42 pm, Peter Dev wrote: > > > > /long-task > > every 30 minutes > name-of-the-backend > > > > On Oct 20, 4:16 am, fachhoch wrote: > > > > > > > > > I have a heavy duty servlet whihc takes long time to run , so I added > > a backed.xml and want to call this servlet through a corn job > > servlet , please tell me how to call the backend from a corn job? -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: calling backend servlet from a corn job servlet
/long-task every 30 minutes name-of-the-backend On Oct 20, 4:16 am, fachhoch wrote: > I have a heavy duty servlet whihc takes long time to run , so I added > a backed.xml and want to call this servlet through a corn job > servlet , please tell me how to call the backend from a corn job? -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] DB API read Quota vs. sessions-enabled true
true "App Engine stores session data in the datastore and memcache, all values stored in the session must implement the java.io.Serializable interface." in java session.getAttribute(XY) calls Datastore API READ if data in Memcache not found? (free limit 50K/24hour) Thx. -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: GAE - Vote counting system
After each vote we want to send back the actual state of voted object (actual votes)... so, we need to store the number of votes and not only the deltas. Actual state of the votes we could store in backends cache, and in batch write changes in db. What do you think about this solution? I appreciate your answers! Thx -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: GAE - Vote counting system
Price: - with backends lets say 3 B2 machines = 350USD/Month - UrlFetch Data Sent/Received 0,15USD/GB Limit: - URL Fetch Daily Limit 46,000,000 calls this can be a problem...but I see it is possible to request an increase Write data parallel in DB: Task Queue with rate every 30second could be a solution (check timestamps in cache and write in DB) RESET counters = empty cache in Backends & reset counter of object in DB Backends cache = HashMap with shared counter values or counter values without sharding (just increment value in java hashmap is fast enough) With backends we don’t need sharding I thinkwhat do you think? Thx. -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: GAE - Vote counting system
Sorry, 100 000 000 counters On Sep 27, 4:53 pm, Peter Dev wrote: > Shared counter is cool and I use it... but if you have millions of > objects I cannot imagine how to manage them.1 000 000obj x 100 shards =10 000 > 000counters > > 1. How to reset them to 0 in specified periods? > 2. How to set the shared sum for each object to show top 100 objects? > 3. Too much DB API Calls (each vote makes write in DB) > > Any ideas...? Thx -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Re: GAE - Vote counting system
Shared counter is cool and I use it... but if you have millions of objects I cannot imagine how to manage them. 1 000 000 obj x 100 shards = 10 000 000 counters 1. How to reset them to 0 in specified periods? 2. How to set the shared sum for each object to show top 100 objects? 3. Too much DB API Calls (each vote makes write in DB) Any ideas...? Thx -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] Datastore APIs new pricing - Query (FirstResult/MaxResults)
http://code.google.com/appengine/kb/postpreviewpricing.html#two_entities_fetched_operations_consumed
*** Query like this:
Query query = session.createQuery("select u from User u order by
u.age");
query.setFirstResult(10);
query.setMaxResults(30);
= 30 read ops (first 10 skipped) or 40 read ops (GAE read all the 30
entities in background)?
*** Second question which price is valid:
http://code.google.com/appengine/articles/managing-resources.html
(0.7usd mil/read ops)
or
http://www.google.com/enterprise/cloud/appengine/pricing.html
(0.07usd 10k/read ops)
Thanks
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[appengine-java] Datastore APIs new pricing - Query (FirstResult/MaxResults)
Datastore APIs new pricing - Query (FirstResult/MaxResults)
http://code.google.com/appengine/kb/postpreviewpricing.html#two_entities_fetched_operations_consumed
- one more question. Query like this:
Query query = session.createQuery("select u from User u order by
u.age");
query.setFirstResult(10);
query.setMaxResults(30);
= 20 read ops (first 10 skipped) or 30 read ops (GAE read all the 30
entities in background)?
AND which price is valid:
http://code.google.com/appengine/articles/managing-resources.html
(0.7usd mil/read ops)
or
http://www.google.com/enterprise/cloud/appengine/pricing.html
(0.07usd 10k/ read ops)
Thanks
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[appengine-java] Re: Using async-session-persistence
http://code.google.com/appengine/articles/managing-resources.html For Java HTTP sessions, write asynchronously - HTTP sessions (Java) lets you configure your application to asynchronously write http session data to the datastore by adding to your appengine-web.xml. but parameter 'queue-name' is required! :-) On Sep 3, 8:53 pm, John wrote: > http://code.google.com/p/googleappengine/issues/detail?id=5774 > > Star it > > On Aug 30, 7:28 pm, Spines wrote: > > > > > > > > > I'm getting this same error after enablingasync-session-persistence, > > except 100% of the time. It shows this error in the logs: > > > javax.servlet.ServletContext log: _ah_queue_deferred: Deferred task > > failed exception: > > com.google.apphosting.utils.servlet.DeferredTaskServlet > > $DeferredTaskException: java.lang.ClassNotFoundException: > > com.google.apphosting.runtime.jetty.DeferredDatastoreSessionStore > > $DeferredSave > > > Any ideas? > > > On Aug 1, 7:34 am, gk wrote: > > > > Greetings, > > > > still have not found any clues what could cause "async-session-> > > > > persistence" tasks to fail with HTTP status code 415 (Unsupported > > > Media Type). > > > > Any ideas? > > > > On Jul 27, 9:16 pm, gk wrote: > > > > > I am experimenting with > > > queue-name="default"/> to store https session data; at first it seems > > > > to work fine with the "default" default queue settings; multithreading > > > > is switched on for the application. > > > > > It appears that there is some kind of collision, as the tasks seem to > > > > succeed when the rate of incoming requests is low. > > > > > When I open a browser window and reload 50 pages from the site at once > > > > it seems to work fine and the queue is filled up with some tasks. Most > > > > ot the tasks succeed. > > > > > The problem is that around 30% of the "async-session-persistence" > > > > tasks fail repeatedly with HTTP status code 415 (Unsupported Media > > > > Type) and there is no further indication of the cause in the queue or > > > > in the server log. -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
[appengine-java] GAE - Vote counting system
We are developing an application, where users can vote for many objects. (for example, voting the best music video of the week) - This means, we have millions of possible objects to vote for, and millions of users To our best knowledge, after taking in consideration different options, the best (or the only) voting system is: Memcache+Bulk DB write in DB - If number of objects in Memcache will achieve a specified limit (for example 3000) then write in DB. The writing speed into DB is about 100/sec. This also means, if we would set the above mentioned 3000 objects, the writing would last for 30 sec... The problem; during save in DB, voting must be blocked. In other words, if from many millions of objects, there are 3000 achieved voted objects, we need to write it into DB and it can happen too many times, and blocking the whole voting mechanism. If we do not block the voting whilst writing in DB, the result could be wrong number of votes from cache (see Workflow: step 3). Workflow: 1. vote received 2. find object in memcache 3. if not found in memcache get from DB and put it in 4. increment the number of votes of the object in memcache 5. check object number in memcache 6. if necessary, save in DB and empty memcache ... -- 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 google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
