Re: Training in Green Screen Java performance and debugging?

Luis Colorado skrev den 07-12-2007 23:06:

Your situation is interesting: during the last decade IBM efforts have focused on moving iSeries veterans people to Java, but they have forgotten about people like you, coming on the opposite direction.

Sure feels like it. Probably they never expected such a thing to happen :)

For starters, I would suggest taking a look to http://search400.techtarget.com/originalContent/0,289142,sid3_gci996499,00.html

Thanks. Will take a thorough look.

Considering your current situation, perhaps it would be better if you post specific questions about your particular problem, and maybe we can help you with that.

For starters, you could post the following information: the description of your problem, the version of operating system you are running, what kind of application server you are using, your version of Java, and so on.

Sure. This particular problem was a Java 1.3 program doing ftp-transfers which repeatedly got stuck in TIMW. Since this was ancient production code from before my time we could not just throw new versions in there, and I could not attach a debugger (no network access but telnet and ftp) so I could not ask WHERE this happened. Usually I have a stack trace to deal with but I could not figure out how to get one. Well, option 11 on the job gave me a call stack window, and THANKFULLY the stack entries for the java code is very readable so it was very easy to identify the culprit (an accept() waiting for a connection which never came). I believe this is Java 1.3 under V5R1.

Here I would have loved to be able to get a readable Javastacktrace or just the option 11 to a spool file (perhaps even in IFS? *oh*) so I could get an overview much faster than poking around in the call stack stuff.
We also have another system which runs my code noticeably slower than on our development system, and where we have ruled out insufficient memory pool or batch/interactive but not gotten much further yet. From Unix I am used to top and sar which can tell me the paging activity (swap) for a given process and WHY and WHERE it waits. I would like similar knowledge for AS/400 - WHY is the system not giving my process top prority and resources? WHERE does all the resources go? etc. If I recall correctly this is Java 1.4 on a V5R4.

And naturally all this must be doable in a green screen. I need to be able to work with the tools intended for the system instead of whining about missing network access.

I found a AS/400 performance analysis manual on a shelf - I believe I should be able to use that information just to get started .

Thanks for your replies - it helps to play ball with somebody.