How to prevent multiple threads per session

["Guernsey, Byron (GE Consumer & Industrial)" <BY...@GE.COM>]

 
I have a bit of a problem where deep in a servlet there is some
synchronized code that is synchronized on an object in session.  On a
rare occasion, that code runs very slowly when a long report is running
or a database slows.  This causes the users of the application to keep
clicking stop and refresh- thinking their request is going to run.
Recently when the server stopped responding, I did a kill -3 and found
almost all of the threads waiting for that synchronzied session object-
meaning 1 user had managed to consume a large number of threads be click
refresh.
 
I realize that I could modify the code to fail out if it couldn't grab
the monitor in a set period of time, but I'd prefer to cancel the thread
that has no web browser endpoint associated with it- the one that holds
the monitor and won't release it until its done with its query.
Basically, if someone refreshes, I'd like to abort any threads they
already have running- or simply allow tomcat to abort the processing
when the threads endpoint goes away.
 
Is there any way I can accomplish this?
 
I'm using Tomcat 4.1.31 and Mod_jk2 on apache 2.0.52
 
Thanks,
Byron
 
 
==============================
Byron Guernsey
Senior Software Architect
GE Consumer & Industrial Systems
(502) 452 - 5101
 
 

Re: How to prevent multiple threads per session

[sven morales <ak...@yahoo.com>]

Hi,
   Filters.  There was a filter code developed by
Ivelin Ivanov and Kevin Chipalkowsky that maybe be
applicable to your needs.  It is called
RequestControlFilter.  
   If a user makes two request, A and B then A will be
processed first while B waits.  When A finishes, B
will be processed.  If a user makes three or more
requests ( e.g. A, B, and C) then the first will be
processed (A), and then the after it finishes the last
will be processed (C), and any intermediate requests
will be skipped (B).

aka_sergio
--- "Guernsey, Byron (GE Consumer & Industrial)"
<BY...@GE.COM> wrote:

>  
> I have a bit of a problem where deep in a servlet
> there is some
> synchronized code that is synchronized on an object
> in session.  On a
> rare occasion, that code runs very slowly when a
> long report is running
> or a database slows.  This causes the users of the
> application to keep
> clicking stop and refresh- thinking their request is
> going to run.
> Recently when the server stopped responding, I did a
> kill -3 and found
> almost all of the threads waiting for that
> synchronzied session object-
> meaning 1 user had managed to consume a large number
> of threads be click
> refresh.
>  
> I realize that I could modify the code to fail out
> if it couldn't grab
> the monitor in a set period of time, but I'd prefer
> to cancel the thread
> that has no web browser endpoint associated with it-
> the one that holds
> the monitor and won't release it until its done with
> its query.
> Basically, if someone refreshes, I'd like to abort
> any threads they
> already have running- or simply allow tomcat to
> abort the processing
> when the threads endpoint goes away.
>  
> Is there any way I can accomplish this?
>  
> I'm using Tomcat 4.1.31 and Mod_jk2 on apache 2.0.52
>  
> Thanks,
> Byron
>  
>  
> ==============================
> Byron Guernsey
> Senior Software Architect
> GE Consumer & Industrial Systems
> (502) 452 - 5101
>  
>  
> 



		
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