On Aug 22, 2011, at 1:01 PM, Chuck Hill wrote: > On 2011-08-22, 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. :-) > > Then extra, extra hard. I do know C, or did, but that code is little much for > what I remember. I can sort of follow how it works. Finding bugs in it... > not so much. > > >> 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 a newer version of Apache or mod_webobjects you can try? Are you > using the builds from mDimension's site?
Yes, I got the one linked from the wiki which is hosted on mDimension. http://webobjects.mdimension.com/wonder/mod_WebObjects/Apache2.2/macosx/10.6/mod_WebObjects.so I updated it again yesterday just hoping that maybe I had something old that had a fix I needed. >> 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? > > I don't think so. > > Chuck > > > -- > Chuck Hill Senior Consultant / VP Development > > Practical WebObjects - for developers who want to increase their overall > knowledge of WebObjects or who are trying to solve specific problems. > http://www.global-village.net/products/practical_webobjects > > > > > > > _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list (Webobjects-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
