Re: Persistent Sessions in DB connection for QZDASOINIT, implemented by Nathan

Pete Helgren skrev:

really. The connection pools are tracked by what is called a role (with a roleID). That role ID is associated with a connection with a specific set of overrides (we use multi-membered files where the members are different fiscal years), and library list (each role may point to a different application set that needs different libraries). So this isn't really pooling at the user level. It pools at the "role" level which has the library list and file overrides which are needed. Many users could be using the same "role" and thus using the same pooled connection.

Ok, so you have pooling at the "role" level, which is most likely with a few roles shared by many users? Then it can probably benefit quite a bit from pooling.

I have one installation where there are about 100 concurrent users banging on the application (a Java servlet with a JDBC connection) and about 200 concurrent users on the RPG application using the same database. It uses a single Tomcat instance. The LPAR it runs in has been allocated 4GB memory and 1 processor.

Have you done any metric measurements on this installations, i.e. memory usage, gc's, responsiveness, etc.?

If this had to scale to say, 1000 concurrent users, I am sure we'd run out of gas somewhere. The customer is currently considering box replacement options and they are leaning, I think, to going to a Bladecenter H and dedicating a single blade to application serving, a blade to traditional RPG workloads and DB serving and a blade for development, but it is still early in the process of weighing pros and cons of how to grow the Java workloads. The hope it to keep it simple without investing in a "farm" (although some may see three blades as a "farm").

Perhaps you should let the customer consider migrating the Tomcat part to another x86 blade to run a Hotspot based JVM on it? Not because it is better as such, but because there are many more people who know how to tune it.

BTW Nathan, the latest iteration in the company you are referring to is to use Adobe's RIA technologies (Flex and AIR I think) to develop web applications. I haven't seen anything new shipped in either Java or Relational Web in the past year or more.

I have grown to think that Java is rather tedious to do web stuff in. There is simply too much plumbing that needs to be done. Sigh.


I have spent some more time looking at the stored procedure calling of cobol, simply to get the freedom to choose any language who knows how to speak to the database. I found that the free profiler available for Eclipse 3.4 allowed me to pinpoint a bottleneck in some library code I wrote to make fixed format structures readable. I thought WSDCi had one, it doesn't. Sigh.

/Thorbjørn