Hi Adligo, On Tue, Sep 8, 2009 at 6:39 PM, Adligo <[email protected]> wrote:
> > Hi Nick, > > Please see below; > > On Sep 4, 10:04 am, "Nick Johnson (Google)" <[email protected]> > wrote: > > 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. > I understand this, which is why I was asking if you could pay for > more. > So can you? > No. As stated, this is not something App Engine is designed to support, and thus your number of concurrent requests is limited proportional to the traffic your app gets. > > > 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! > Well this depends a little on Session management, the > ArrayBlockingQueue > I mentioned is stored as a Session Attribute. I assume that the app > engine must be > keeping the Session in a location that can be accessed by all > threads. Otherwise how > could anyone maintain any sort or security on the server side (most > Jaas HttpFilters I have seen store the Subject[User] as a Session > Attribute, including 2 that I wrote by hand for custom requirements > and Spring security) ? > The issue is not multiple threads on one runtime, but the fact that a single App Engine app may be running on multiple runtimes, on multiple separate machines. You cannot expect a standard locking primitive to function across multiple machines. Or in other words how does the app engine treat HttpSessions and their > attributes, in the normal J2EE way, or some other way? > Sessions are stored in the datastore. -Nick Johnson > > Cheers, > Scott > > > > -Nick Johnson > > > > > > > > > > > > On Thu, Sep 3, 2009 at 9:06 PM, Adligo <[email protected]> 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/. > .. > > > > > 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)" <[email protected]> > > > 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 <[email protected]> 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- 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 [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?hl=en -~----------~----~----~----~------~----~------~--~---
