Re: Performance problems using dataqueues to NT.

Unfortunately in a case there is a two second delay.  The flow is:
     The application calls the read with wait method on the Toolbox DQ
     object
     Toolbox sends a DQ read request to the server
     The server checks the queue.  If a matching entry is on the queue it
     is returned.  If not, go to step 3
     If a matching entry is not on the queue the server checks the socket
     to see if the client decided cancel the read.  If nothing new is on
     the socket the 2 second wait happens.  During this wait no events are
     presented to the server, so if something gets on the data queue a
     millisecond after the 2 second wait begins, we don't know until after
     the 2 second wait.  A lot more is going on but beyond the scope of
     this discussion.

So, the two second wait in step 4 has to do with the way the server waits
for an entry to show up on the queue.

I am not having a lot of luck convincing the server folks to change their
design.  Our experience has been that this happens only on a read with
wait.  The wait is almost always greater than 2 seconds.  If you are on the
server side you say based on the API called, the app seems to be willing to
wait over 2 seconds for the data.

While the discussion goes on there are a couple things the client can do.
If data "usually" arrives in less than two seconds you could wait before
doing the read, or read, wait on client, read.  In each case the DQ read
should not wait for data.  If no item is on the queue the Java side should
get control without data.  Not great solutions but this could eliminate
some of the delay.

David Wall
AS/400 Toolbox for Java


Henderson Mads Peter <maheo@wmdata.com>@midrange.com on 09/27/2000 05:31:28
AM

Please respond to JAVA400-L@midrange.com

Sent by:  owner-java400-l@midrange.com


To:   "'JAVA400-L@midrange.com'" <JAVA400-L@midrange.com>
cc:
Subject:  Performance problems using dataqueues to NT.



I am working on a webapplication running on NT. The application makes use
of
a database on AS/400. To communicate with the AS/400 I use 2 dataqueues and
the AS/400 toolbox to read from one and write to the other (on the AS/400
it
is vise versa using Cobol programs). My team has done a lot of work in
increasing communication speed. Our main problem in increasing the speed
further is that we have  2 secs delay from an entry is made on our
input-dataqueue until the java program receives the entry. The funny part
is
that if we stall the Cobol program that writes to the queue for more than 2
secs the java program recieves the entry immediately. It should be noted
that the java programs used for reading and writing are running seperate
threads so the reading thread should be unaffected by the writing thread.

The result of this is that the time used from an entry is made to the
dataqueue and returned is 2 secs + a fraction. The fraction representing
the
real processing time.

Thank you for any input on how to get by this problem

Mads Peter Henderson
maheo@wmdata.com

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