Hi Adligo, App Engine is not really designed for 'long polling' setups like you describe. Since the number of simultaneous runtimes your app has at a given traffic level is limited, waiting like this will consume them all very quickly. Also, because your app may be distributed over many computers, a synchronization primitive like the one you're using will not work - the process doing the notifying may not be on the same machine as the process(es) that need notifying!
-Nick Johnson On Thu, Sep 3, 2009 at 9:06 PM, Adligo <sc...@adligo.com> wrote: > > Hi Nick, > > I am not calling sleep but I am using a server side > ArrayBlockingQueue, with methods like > queue.poll(waitTime, TimeUnit.SECONDS); > So I am not buffering but simply responding with current messages > and if there arn't any waiting until some show up and then > responding. If no messages show up in 20 seconds or so I respond with > a empty message list and then the client sends a new request. > > I am using GWT's rpc, here is my service api, which is open souce. > > http://cvs.adligo.org/viewvc/gwt_util/src/org/adligo/gwt/util/client/rpc/MessageService.java?view=markup > > So I am anticipateing that I will have a lot of threads that are > simply waiting on the ArrayBlockingQueue's poll method. This allows > me to do things like; > 1) send log messages between two browser windows > 2) send system messages from a admin console to anyone viewing the app > like; > (System is going off line in 10 minutes) > (There is pizza in the lobby for anyone who wants it) > exc > 3) Implement a IM client in the browser > 4) Send 'event' data between browser windows so a user can click a > button in one window > and have it do something to another window. Currently the only > application of this is to > reload the adligo_log.properties file, so you can change your log > levels at runtime. However > there are a lot of other applications for this, windows can now > communicate. > > Also there shouldn't be much of a drain on the processor, since most > of the threads are simply waiting (not doing a lot of processing). It > just requires a large number of threads (one per browser window). > > Cheers, > Scott > > PS I would really like to host on Google Apps, the server > http://zeuhl.adligo.com/gwt_util_demo_v3_1/GwtDemo.html?show_log=true > was down all morning, since I had my phone turned off to respect for a > concert last night I didn't get a 'your server is down' text from > hosttracker.com. > > On Sep 3, 3:51 am, "Nick Johnson (Google)" <nick.john...@google.com> > wrote: > > Hi Adligo, > > The limit on concurrent instances of your app is not a hard one - it will > > increase as your app gets more traffic. The only situation you're likely > to > > run into it is if you have a lot of requests that take a long time to > > complete - eg, if you're calling time.sleep() in your request handler. As > > long as you're serving your requests reasonably efficiently, you can > expect > > the number of concurrent requests your app is allowed to scale up with > load. > > > > -Nick Johnson > > > > > > > > > > > > On Wed, Sep 2, 2009 at 1:33 AM, Adligo <sc...@adligo.com> wrote: > > > > > Hi, > > > > > I am developing a app (or more than one) that I would like to host > > > on Google App Engine, however the architecture of the app involves > > > cranking up the maxThreads (I am using my home grown hosting which now > > > has Tomcat set to 2,000 maxThreads :) ). > > > > > For example (1 six+ year old machine in my basement) > > >http://zeuhl.adligo.com/gwt_util_demo_v3_1/GwtDemo.html?show_log=true > > > > > I was reading somewhere that my app will be limited to 30 Max > > > simultaneous requests (maxThreads), and I didn't see anything about > > > being able to change this (EVEN IF YOU PAY FOR IT). > > > > > So is it possible to change this? > > > If not why, it should be billable like everything else... > > > How much would it cost? > > > > > Also I think that it seems like a silly limit (although probably a > > > good starting point for most apps). Some apps need a lot of threads, > > > some have a lot of page requests. > > > For instance my app needs a lot of threads (the above version uses > > > at least 1 per user ALL THE TIME) and will go to 2 per user in the > > > next release :) Or rather to be more specific One thread per open > > > browser window, so I can 'send' data to the browser window in near > > > real time with out having the browser window send a request every > > > millisecond (which causes other problems). > > > So it will be limited to 15 users on Googles App Engine yikes! > > > > > Cheers, > > > Scott > > > > -- > > Nick Johnson, Developer Programs Engineer, App Engine- Hide quoted text - > > > > - Show quoted text - > > > -- Nick Johnson, Developer Programs Engineer, App Engine --~--~---------~--~----~------------~-------~--~----~ 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-appengine@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 -~----------~----~----~----~------~----~------~--~---
