On Mon, Feb 23, 2009 at 6:33 PM, Paul O'Rorke <[email protected]> wrote:
> > Yes, even tho I wasn't living in Silicon Valley at the time, I did > learn about virtual memory as a kid and then again in operating > systems courses well before I got my Ph.D. in C.S. ;). > > I just did a little experiment where I waited patiently this time > after not getting an immediate response and I did get another "server > did not respond" type message. > After getting this mesage, I tried clicking again on an Ajax checkbox > a couple of times and it worked fine without my having to reload the > page. > > So your theory, I take it, is that virtual memory is so slow swapping > the server process back in that the client gives up and thinks it is > never going to respond? Is there some timeout in lift and/or in the > Ajax Javascript code that can be tweaked to let it wait a little > longer for a response before giving up? The Ajax stuff retries the server based on the LiftRules.ajaxRetryCount setting (by default 3). It backs off by doubling the wait time between tries, so adding LiftRules.ajaxRetryCount = Full(5) to Boot.scala should address the issue. On a broader note, running any JVM code on a machine that is using significant amount of swap space is less than optimal. The JVM's garbage collector touches every page in a process at least onces, so in order to do a full GC, the whole process gets swapped in. > > ---Paul O > > On Feb 23, 4:06 pm, David Pollak <[email protected]> > wrote: > > On Mon, Feb 23, 2009 at 3:55 PM, Paul O'Rorke <[email protected]> wrote: > > > > > David: I think you are probably right that it is something external > > > to lift or scala as it seems to be intermittent, happening sometimes > > > but not others under what seem to be the same circumstances. > > > > > The server process is on a mac book pro laptop for now and it may well > > > be getting swapped out although not for a screen saver as I am usually > > > keeping the machine busy working on other things. But wouldn't a > > > request to the server cause it to be swapped back in again? > > > > Yes. This is how virtual memory works. > > > > How much RAM is in your machine? > > > > Perhaps some Mac-head on the list can tell us how to determine how much > of a > > process is actually swapped to disk. > > > > > > > > > > > > > I'm using Safari almost all the time. Thanks for suggesting Chrome as > > > a good alternative for this application. > > > > > It gives a bit of a feel of flakyness if you go to do something simple > > > and it doesn't work as intended so I thought it worth noting and will > > > keep a lookout to see if it happens often enough and regularly enough > > > that I can replicate it simply somehow. > > > ---Paul O > > > > > On Feb 23, 2:40 pm, David Pollak <[email protected]> > > > wrote: > > > > Paul, > > > > > > This can result from a number of things: > > > > > > - The process that's running your web app gets swapped out on the > > > > server. If you're running on Linux, this is less likely to happen > if > > > you > > > > have enough RAM. I've seen Windows swamp processes out so it can > run > > > the > > > > screen saver. > > > > - Your browser does not do well with long running JavaScript. > > > Firefox, > > > > in my experience, is particularly bad about this. I have to > restart > > > Firefox > > > > almost daily. On the other hand, Google Chrome seems to be the > best > > > browser > > > > in terms of hanging out on the same page for days, weeks, at a > time. > > > > > > I have a browser window open tohttp://demo.liftweb.netallthe time. > > > Other > > > > than the above-mentioned need to periodically restart Firefox, the > page > > > is > > > > always responsive. > > > > > > If you can put together a reproducable case of this problem, I'll > look > > > into > > > > it. > > > > > > Thanks, > > > > > > David > > > > > > On Mon, Feb 23, 2009 at 2:34 PM, Paul O'Rorke <[email protected]> > wrote: > > > > > > > Several times now when I've left a page with Ajax checkboxes and > > > > > textboxes sitting for a while, and then when I've gone to check a > box > > > > > or type in a textbox, there is no response from the server. In the > > > > > console window, I see nothing unusual. > > > > > > > Sometimes I used to get "could not reach server" messages in this > sort > > > > > of situation but I don't seem to be getting those anymore or else > I'm > > > > > just not waiting long enough for them. > > > > > > > This is in a web app that I want to be able to treat like a desktop > > > > > app. It has a very long session timeout but I have not changed any > > > > > other timeouts like the ajax timeout. (Perhaps I should?) > > > > > > > A workaround is just to reload the page. (I think that tends to > > > > > happen anyway sort of automatically on my iPhone but not on my > > > > > desktop.) > > > > > > -- > > > > Lift, the simply functional web frameworkhttp://liftweb.net > > > > Beginning Scalahttp://www.apress.com/book/view/1430219890 > > > > Follow me:http://twitter.com/dpp > > > > Git some:http://github.com/dpp > > > > -- > > Lift, the simply functional web frameworkhttp://liftweb.net > > Beginning Scalahttp://www.apress.com/book/view/1430219890 > > Follow me:http://twitter.com/dpp > > Git some:http://github.com/dpp > > > -- Lift, the simply functional web framework http://liftweb.net Beginning Scala http://www.apress.com/book/view/1430219890 Follow me: http://twitter.com/dpp Git some: http://github.com/dpp --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Lift" group. 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