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From "Malcolm Edgar" <>
Subject Re: [PATCH] improved HTMLManagerServlet
Date Fri, 24 May 2002 03:58:00 GMT
Glenn Nielsen wrote:

>I have a number of comments.  First thanks for working on improving the
>1.  GC should not be user initiated, it should be left to the JVM.
>     In addition, when virtual hosting web sites, those who have permission
>     to manage applications for a particluar host may not be the
>     system admin for Tomcat.  I wouldn't want them to be able to trigger a 
>     The GC option needs to be removed.

I agree the GC should not generally be run by users, however the access to 
the manager app should limited to admins and developers, so I dont believe 
this would be an problem.

I had the experience of developing/profiling Tomcat apps located in the US 
while working in Australia for Avaya. To do this we developed a performance 
monitoring app, doing this sort of thing which was extremely useful.

>2.  The js which you added for onClick really isn't necessary.  The
>     HTMLManagerServlet should be usable w/o JavaScript enabled
>     in the browser. It should be removed.

How would you do this in a POST request? I could use GET request but params 
url string is exposed, though I suppose this doesn't really matter for this 

>3.  The listing of memory usage isn't really needed if GC is removed.
>     It doesn't provide info that is of benefit to someone
>     who just manages web applications and is not the Tomcat sysad.
>     A Tomcat sysad would be better off using the -verbose:gc arg to
>     java when starting Tomcat so that they collect GC data which they
>     can later graph to profile the Tomcat JVM memory usage.

I think it is handy to have a non-intrusive (although limited) way of 
examining memory status of servers in production or undergoing UAT.

That said I am not married to it, so I can remove it if required.

>These comments are just from a quick review of the code, I haven't
>compiled it and tried it out.
>list.html wasn't attached.

Please see attached file, not sure what happend the first time. Thanks for 
the feed back.

Regards Malcolm Edgar

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