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? > 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 ([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]
