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Thread: Can maxed-out web server CPU really handle more instances of Alpha

  1. #1
    "Certified" Alphaholic
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    Default Can maxed-out web server CPU really handle more instances of Alpha

    So, I am really having a hard time believing that a web server that has a maxed-out CPU, based on the steady 100% CPU utilization shown by Windows Performance Monitor, could actually handle more instances of Alpha under IIS or traditional AA WAS.

    What am I missing here, how can the Windows Performance Monitor be so wrong that it would actually work to put more running instances of IIS or WAS on the system?

    When I stress test my app, each of the four CPU cores shows 100% usage in the graph. I estimate the CPU cores can handle about 5 users at a time, and even at that small number, performance is not very good. (These are "busy" users - requesting new ~20 record Grid pages every couple of seconds.)

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    Volunteer Moderator Steve Workings's Avatar
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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    Rich - something doesn't sound right. And as I'm sure you know, there are a lot of factors.

    Are you sure all that CPU usage is really from your app? What does it look like when you don't have the app running at all? And then when you start your app and users start using it, can you attribute the growing consumption to that activity?

    I've seen one popular malware package and other pieces of Windows consume a whole lot of CPU.

    And, how much RAM do you have?
    -Steve


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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    6GB RAM.
    SQL Server is on another server and its CPU usage is quite low.
    I ran the load test twice and yes, the CPU usage is low on the Web Server until the cloud-based load testing servers spin up and start adding users to the system.
    I had all regular users off of the system and the web-site that services them had been disabled in IIS, so only the load testing web site was running in IIS.

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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    You're plenty experienced so I have confidence your app is well-designed, etc. But after some thought, I wonder if it's worth some review.

    Grids of course are not as good as some of the newer controls. But before anything too deep, I wonder if you could load test it against some extremely simple page. Or, make a very simple page with a list showing the same data, and test against that.

    And, if your app is dependent on continuous and new retrievals of records like this, it's probably wise to consider lists or viewboxes as substitutes anyway for best performance.
    -Steve


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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    Rich, you are assuming your app is what causing the issue, every time I've seen this, it is a result of outside attacks on the alpha server being hit sometimes 100's of times a second, these are mainly from china you may need to add software to manage these attacks, as it causes a denial of service like what you are experiencing. RDPGuard will help you verify and resolve it.

    Hope this helps.
    Insanity: doing the same thing over and over again and expecting different results.
    Albert Einstein, (attributed)
    US (German-born) physicist (1879 - 1955)

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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    Any continouos server side workflow (or simililar situation) will in practise immediately kill Alpha server. You can test this with most simple loop. This is good to remember.

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    "Certified" Alphaholic
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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    Steve Workings,
    Yes there are a chain of three Grids in this test scenario. The 3rd Grid (the one opened and closed 10 times in the load script) is easily replaced with a UX with a LIST. I am recoding the test script to work under a different testing platform and I will have it open the UX version on that 3rd step. I had done the test with a Grid in the third step as I had created that Grid to run faster than the UX. On my Dev computer I observed a simplified Grid had a much smaller payload than the UX and the Grid seemed to load faster on my Dev computer than the UX. But the time savings I saw on my Dev computer did not translate to any savings on the Server.

    Ken,
    Do you mean if I am doing my own xbasic processing or are you saying that just the stuff Alpha does to process a Grid will overwhelm the server?

    Pete,
    Yes, I suppose the server could be busy trying to handle bogus requests that I don't know about. But the CPU usage does start out quite low and only gets pegged when the load test users come online. I will see if IIS has a log of requests I can look at.

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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    Just saying.
    Insanity: doing the same thing over and over again and expecting different results.
    Albert Einstein, (attributed)
    US (German-born) physicist (1879 - 1955)

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    "Certified" Alphaholic kkfin's Avatar
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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    For WAS. There is two things that has direct impact for performance here. First is Application Server and other is code running in server.

    Application server uses server threads to balance traffic. Normally there are 8 available at start and 4 for spare. These are quick and lack is slow. But if more is needed then to activate more threads takes little time which has direct impact for performance. Normally 48 threads is maximum. Then you have to wait for one task to get finished to get a free thread. So basically after 12 things get little slower and very soon very slow.

    Application server running in 64 bit Windows can consume 2 GB memory but maybe the real limit is 1GB and then Application server is already far from responsive. The question is anymore who will switch the lights off.

    What comes to code in server some xbasic code can be running simultaneously some not. This is the reason why for example a simple loop can kill whole server. Also note. Most simple UX/Grid is a quite punch of code. If many loads it same time the size of module has direct impact to performance.

    By the way. There is an easy xbasic function A5W_AnalyzeWebAccessLogs() you can use to check access logs using a web page. I have find that it do not work with reverse proxy at least with my current combination. I get some ajax errors.

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    Default Re: Can maxed-out web server CPU really handle more instances of Alpha

    Keep pushing Rich.
    Very interested in this thread

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