On Aug 22, 2011, at 12:53 PM, Chuck Hill wrote: > On 2011-08-22, at 12:48 PM, Tim Worman wrote: >> On Aug 22, 2011, at 11:51 AM, Tim Worman wrote: >> On Aug 22, 2011, at 11:38 AM, Chuck Hill wrote: >>>> On 2011-08-21, at 12:43 PM, Tim Worman wrote: >>>>> On Aug 21, 2011, at 11:52 AM, Chuck Hill wrote: >>>>>> On 2011-08-20, at 4:02 PM, Tim Worman wrote: >>>>>> >>>>>>> Back in January I started this discussion on this same topic: >>>>>>> >>>>>>> http://lists.apple.com/archives/webobjects-dev/2011/Jan/msg00224.html >>>>>>> >>>>>>>>> I have an app that, during the course of normal usage, is starting >>>>>>>>> httpd processes on the server that instantly hit 100% CPU usage of >>>>>>>>> one core. This can happen multiple times during times when the app is >>>>>>>>> under heavier load. After some time I can have many httpd processes >>>>>>>>> where TOP reports each using 100% of a core. When I try to log into >>>>>>>>> the app and poke around to try and reproduce the issue, I am unable. >>>>>>> >>>>>>> This is an update to my original post hoping to see if there are >>>>>>> anymore thoughts on origin. More recently, I have been able to >>>>>>> reproduce the issue in my own usage of the app - something I wasn't >>>>>>> able to do before. It seems to be easier to generate the issue now that >>>>>>> there are more ajax requests. The methods executed by these requests >>>>>>> are not intensive or long responses and should return a result in >>>>>>> seconds. Some symptoms: >>>>>>> >>>>>>> - When the actions are executed, busy indicators properly spin while >>>>>>> the browser awaits a response from the server. When the issue occurs, >>>>>>> the response never comes. >>>>>>> - while continuing to await a response there is concurrently an httpd >>>>>>> process that pegs he processor at 100% >>>>>>> - if I kill the process on the server, the browser immediately updates >>>>>>> properly as if the request had run properly >>>>>>> >>>>>>> It's almost as if apache is somehow receiving an ill-formed request and >>>>>>> chokes on it. The problem is, there are no errors in the console or >>>>>>> anything strange in any apache logs. Has anyone ever seen behavior like >>>>>>> this or have any ideas as to how I could analyze it further? >>>>>> >>>>>> I've seen something like this. It appeared that the woadaptor (i.e. >>>>>> mod_webobjects) did not believe that it had received all of the response >>>>>> from the application. The app had nothing more to send and so the >>>>>> woadaptor just hung there waiting for data that would never come. I did >>>>>> not track down why this happened, but it did seem to be load related. >>>>>> My suspicion was that there is a concurrency bug in the woadaptor. >>>>> >>>>> I'm really at a loss about what to do about it. It's only gotten worse as >>>>> I've included more ajax actions in my app - and, of course, I don't >>>>> experience this behavior in development. I just deployed a major update >>>>> to my app - pretty much unaware that a small problem was going to become >>>>> a big problem with the new version. >>>>> >>>>> In one example, a have a calendar where clicking on a day simply calls an >>>>> AjaxUpdate marking that date as selected to the calendar. The result also >>>>> has to update the entire page though because other things on the page >>>>> need to change in those circumstances. This alone can cause the issue - >>>>> but not always. And it happens even when I'm the only logged in user - so >>>>> the load isn't high. >>>>> >>>>> As one solution, I've considered rolling a custom apache instead of using >>>>> Apple's. But since the server also runs shibboleth, the setup isn't >>>>> exactly simple. But I'm really not sure how to ascertain if the problem >>>>> is the woadaptor or how I can settle it. >>>> >>>> >>>> You could try the CGI adaptor and see if that makes any difference. If it >>>> IS a bug in mod_webobjects... that could be hard to find and fix. >>> >>> Yeah, I'd say so. I don't even know C. :-) I'm gonna pursue some other >>> things first - like a possible hardware issue, or other software. I'm going >>> to try a deployment on another server and see if that has any effect - also >>> without shibboleth. Is there any chance that an issue with the id's of page >>> elements could cause an issue like this - say if they're dynamic and the >>> response doesn't find a matching id? >> >> One other thing - if this was a bug in mod_webobjects, wouldn't a whole lot >> of projects being experiencing this same issue? Obviously, there are wo >> projects out there taking on a lot more load than mine. I have to think >> there is something about this specific deployment OR something about my >> specific requests that's causing my little hell here. Obviously, in wo, we >> don't construct our own requests in a fine-grained way so that is why I'm >> wondering about some of the elements on my pages. > > > If it is a bug in the adaptor it has to be something very specific, maybe a > size or the value of some bytes at the start or end or the phase of the moon > or... What platform do you deploy on?
What's the possibility that this could be related? http://www.h-online.com/open/news/item/Tool-causes-Apache-web-server-to-freeze-1330105.html > Chuck _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to [email protected]
