How to handle multiple requests to the same servlet at one time?

Hi,
I am new to Servlets. I have doubt regarding ... Handling multiple requests to a servlet at a time.
If we send a single request to a servlet, as know that group of objects such as servlet, servletContext, servletConfig, request, response and etc are created in the server, And if 1000's of requests are sent to a same servlet at a time, and if server memory capacity is less, then 1000's of objects are created in a server which would be heavy burden to Server. How to handle the application and development in such situation?
Kind regards,
veerendra

Hi veerendra reddy ,
By default any web server can will have a thread pool to handle client req's.
In your point also heavy burden to server you are telling that depends on this.
we can configure this min & max size of this thread pool.
by default it will be 0-1000 for tomcat server.
I am not sure in which file this configuration will be.
But I hope in server.xml or some xml file consists this info.
If You what you can edit accordingly. to overcome your heavy burden to server.
Thanks & Regards
Nagendra

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How to handle multiple request in the servlet

how to handle multiple request in the servlet...
Example:
java forum...
i'm login in the java forum at this time 1000 members make login in this....how happended in servlet?
if we use thread how to implement in servlet ?

Serlets are already threaded. The application container instantiates the servlet, then uses this instance in a new thread for every use.
This is the reason that you should use (almost) no instance variables in a Servlet, but rather that (almost) everything should be local to the method.

How to handle multiple exceptions by the same code?

Hi, all:
In my situation I want AException and BException handled by the same code, while CException and DException handled by another code. How can I write my try-catch code in a simple way? Of course I can do the following:
public void TheMainFunction() {
    try {
    } catch (AException e) {
        Handle_AB();
    } catch (BException e) {
        Handle_AB();
    } catch (CException e) {
        Handle_CD();
    } catch (DException e) {
        Handle_CD();
private void Handle_AB() {
private void Handle_CD() {
}But is there a simpler way?
Thanks in advance.

If you have one or two places in your code that need multiple exceptions, just do it with multiple catch statements. Unless you are trying to write the most compact Programming 101 homework program, inventing tricks to remove two lines of code is not good use of your time.
If you have multiple catches all over your code it could be a code smell. You may have too much stuff happening inside one try statement. It becomes hard to know what method call throws one of those exceptions, and you end up handling an exception from some else piece of code than what you intended. E.g. you mention NumberFormatException -- only process one user input inside that try/catch so it is easy to see what error message is given if that particular input is gunk. The next step of processing goes inside its own try/catch.
In my case, the ArrayIndexOutOfBoundsException and
NumberFormatException should be handled by the same way.Why?
I don't think I have ever seen an ArrayIndexOutOfBoundsException that didn't indicate a bug in the code. Instead of an AIOOBE perhaps there should be an if statement somewhere that prevents it, or the algorithm logic should prevent it automatically.

Concurrent multiple requests to the same servlet from same client

          We are using weblogic as our web and app. server. We are using the weblogic oracle pool for database connections. We have jsp and servlets in the second tier with EJB on the third tier.
          We have a problem like this. We have set the oracle pool max size to 40. Some of our database searches takes about 30 seconds. If a user submit a request for such a search, it takes about 30 seconds to respond to the client.
          In the mean time if the user submits the same request again and again (by clicking the URL link in the HTML page continuosly for 50 times), the servlet takes each request, creates new thread for each request, and each thread uses a connection. So our pool runs out of connections and further to that, we get 'resource unavailabe exception' or 'pool connection failed' etc.
          All the users hang. Some times it recover back, but most of the times the server crashes.
          We have not set any time out for pool connection waiting time. By default weblogic keeps the threads waiting for connection indefinitely.
          So, now if somebody want to crash our site, simply they can go and hit a database search link (which takes about 30 secs) 50 to 100 times, and out site will go down.
          What is the good solution for this. I think this is a common problem which many people should have solved. One way is to find and block the user who is hitting many times.
          Any better solutions pl.?
          regards
          sathish


          "Cameron Purdy" <[email protected]> wrote in message
          news:[email protected]...
          > There are other ways to do the processing besides JMS, but the main idea
          is
          > this: DO NOT DO IT ON A WL EXECUTE THREAD IN YOUR WEB SERVER -- those are
          > for your HTTP requests and you don't want to use them up. You can use RMI
          > and have your RMI object spin off a thread.
          Now we're going in circles. I've heard it repeatedly argued here that you
          don't
          ever want to do anything in the server that is not within a server execute
          thread.
          My "big process" needs to run on the server, since it manipulates EJB's
          etc.,
          in the same sense that JavaBeans launched from a JSP page run in the server.
          So, I just don't understand why now it's not ok to use execute threads, when
          I'm going to be initiating a thread of control in the server anyway.
          >
          > Here's the second issue: idempotency. Make sure you pre-assign an ID to
          > the task, and have that ID accompany the task as it runs, use that ID to
          > update a shared resource (perhaps db) to show the progress of the task,
          and
          > keep that ID in the shared resource afterwards so that the task is not
          > repeated unnecessarily (refresh) and so the user's request now shows that
          > the task is complete.
          >
          My solution associates an AsynchTask to object to a session scope JavaBean.
          So, for a given session, there can be only 1 task object, etc. Will this
          work?
          Thanks,
          Jason
          > --
          >
          > Cameron Purdy
          > [email protected]
          > http://www.tangosol.com
          > WebLogic Consulting Available
          >
          >
          > "Jason Rosenberg" <[email protected]> wrote in message
          > news:[email protected]...
          > > Cameron,
          > >
          > > A few questions....
          > >
          > > Is JMS the only way to "kick off the big process". Is there a way to
          > > launch another servlet, or god forbid, another thread, etc.?
          > >
          > > I'd rather not have to use JMS right now, due to time constraints
          > > (it's another thing to have to figure out...).
          > >
          > > Is it necessary to use javascript to redirect? Can't we just use
          > > a simple meta refresh tag, which causes the same jsp to be
          > > hit repeatedly, and which will keep resending the html with
          > > the meta-refresh until the "big process" has completed?
          > >
          > > Also, if we have a jsp which uses a bean with session scope,
          > > don't we then get built in "uid" tracking? The bean instantiated
          > > will necessarily be of the current session, it seems, as long as the
          > > user keeps the same browser window open (or does resending
          > > cause a new session to be started--I didn't think so....).
          > >
          > > Can you elaborate on how the completed process information can
          > > be shared back to the session, and then returned to the browser, etc.?
          > >
          > > Jason
          > >
          > >
          > >
          > >
          > >
          > > "Cameron Purdy" <[email protected]> wrote in message
          > > news:[email protected]...
          > > > This cut & paste feature is getting handy ..
          > > >
          > > > --
          > > >
          > > > 1) The work to be done is assigned a uid or something similar to
          > prevent
          > > it
          > > > from being done twice
          > > > 2) The user presses the button which passes the uid in a hidden field
          > > (for
          > > > example)
          > > > 3) The serlvet responds by kicking off the big process with jms and
          > sends
          > > > back a page that displays a "processing..." message and uses
          javascript
          > to
          > > > redirect (with a place to click just in case javascript is turned off)
          > > > 4) The url redirected to includes the uid to identify the process for
          > > which
          > > > the result is desired
          > > > 5) When the process is completed, the information is placed in some
          > known
          > > > location (e.g. HttpSession or database) and the pending request to
          find
          > > the
          > > > result can return the result
          > > >
          > > > --
          > > >
          > > > Cameron Purdy
          > > > [email protected]
          > > > http://www.tangosol.com
          > > > WebLogic Consulting Available
          > > >
          > > >
          > > > "sathish kumar" <[email protected]> wrote in message
          > > > news:[email protected]...
          > > > >
          > > > > We are using weblogic as our web and app. server. We are using the
          > > > weblogic oracle pool for database connections. We have jsp and
          servlets
          > in
          > > > the second tier with EJB on the third tier.
          > > > >
          > > > > We have a problem like this. We have set the oracle pool max size to
          > 40.
          > > > Some of our database searches takes about 30 seconds. If a user submit
          a
          > > > request for such a search, it takes about 30 seconds to respond to the
          > > > client.
          > > > > In the mean time if the user submits the same request again and
          again
          > > (by
          > > > clicking the URL link in the HTML page continuosly for 50 times), the
          > > > servlet takes each request, creates new thread for each request, and
          > each
          > > > thread uses a connection. So our pool runs out of connections and
          > further
          > > to
          > > > that, we get 'resource unavailabe exception' or 'pool connection
          failed'
          > > > etc.
          > > > > All the users hang. Some times it recover back, but most of the
          times
          > > the
          > > > server crashes.
          > > > > We have not set any time out for pool connection waiting time. By
          > > default
          > > > weblogic keeps the threads waiting for connection indefinitely.
          > > > > So, now if somebody want to crash our site, simply they can go and
          hit
          > a
          > > > database search link (which takes about 30 secs) 50 to 100 times, and
          > out
          > > > site will go down.
          > > > > What is the good solution for this. I think this is a common problem
          > > which
          > > > many people should have solved. One way is to find and block the user
          > who
          > > is
          > > > hitting many times.
          > > > > Any better solutions pl.?
          > > > > regards
          > > > > sathish
          > > >
          > > >
          > >
          > >
          >
          >

Does af:commandButton submit multiple requests at the same time?

Hi experts,
I have a question about af:commandButton behavior.
I have two commandButtons in a page. They are button1 and button2.
Button1 takes a few seconds to complete its request process.
So when I click button1, I can click button2 although button1 request is still being processed.
I checked how ADF faces handled this situation with servlet filter.
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Atsushi

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