12 Supporting On Demand Business Applications with the IBM Problem Determination Tools
During application maintenance
It is a fact of modern development that the person who maintains a given application is not
necessarily the person who wrote it. It is also true that the performance characteristics of an
application can change during its service lifetime.
A profiler such as Application Performance Analyzer can help stop the performance loss that
often occurs during maintenance. An application programmer can use this tool to determine
where the hot spots or heavy loops are in the application. The information about where the
performance bottleneck is located can then be taken into consideration when putting in a fix.
For example, the developer could learn where the heavy loop is, and then do whatever is
possible to avoid adding code to that loop when fixing the problem.
Application Performance Analyzer could also be used after a tentative fix is made that seems
to degrade performance, to help find the cause of that degradation.
These are some other uses for Application Performance Analyzer:
To provide information to a software provider when you run into a performance problem
with their code
To help system programmers determine what parts of a given application are causing a
system performance problem
2.1.2 What Application Performance Analyzer can do
Application Performance Analyzer is a performance measurement and analysis tool that:
Optimizes the performance of existing application resources
Provides maximum flexibility, with support for CICS, Assembler, COBOL, PL/I, DB2, IMS,
and Web Sphere MQ technologies
Eliminates excessive I/O activity and CPU time to increase response times
Improves response time of online transactions and batch turnaround times
Identifies code bottlenecks during initial testing and isolates performance problems in
Application Performance Analyzer collects samples from the monitored address space and
analyzes the system or resource application in the following categories:
An at-a-glance summary of various aspects of the measurement data to help you to
hot spot) which other reports to concentrate on
Total address space utilization of all modules in the address space
CSECT utilization within each load module
Instruction or statement utilization within each CSECT
Assembler, COBOL, and PL/I statement usage within each module.
Direct access storage device (DASD statistics)
Coupling facility usage during the observation session