• Subject: RMI server
  • From: Glenn Holmer <gholmer@xxxxxxxxxxxxxx>
  • Date: Wed, 07 Apr 1999 11:45:55 -0500
  • Organization: Weyco Group, Inc.

I've got an RMI server running on one of our AS/400's (V4R2) that 
is probably not coded properly, and I'm wondering what the possible
side effects of this might be.

I am not multithreading client requests, although sensitive ones
(like getting next available serial no. for a barcode) are marked
"synchronized".  We have had this RMI server in light production
use for a couple of months, but last week used it heavily to bring 
the first 18,000 pairs of shoes into our new warehouse.  All went 
well for about a day and a half, but then the server began to crash
repeatedly with a message like "SQLCURSOR000000007 already open",
received and displayed by the client.  (Could this be some kind of
resource issue on the '400?)

I should note that I am using JDBC and prepared statements with
com.ibm.db2.jdbc.app.DB2Driver.

My question is this: if an RMI server method just returns a value
(without creating another object that starts its own thread, etc.),
what happens when multiple clients hit it?  Do the second, third,
etc. clients just wait?  Does the RMI server itself spawn off any
additional threads to handle this situation?  Does it make any
difference if the methods are marked "synchronized"?  What if a 
client is somehow able to make a second request before the first
has returned?  If I do rewrite it to use multithreading, is there
a limit to the number of threads that can be started?

Any suggestions for improvement would be welcome, as RMI responds
very quickly for us, although I am about to put a *serious* load 
on it as we bring the rest of a million pairs of shoes into the 
warehouse...

I would be happy to attach the source code if anybody wants to
see it.

-- 
____________________________________________________________
Glenn Holmer                          gholmer@weycogroup.com
Programmer/Analyst                       phone: 414.908.1809
Weyco Group, Inc.                          fax: 414.908.1601
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