Timer: Account.store Invocations: 1185 Total Time: 3306555 Average Time: 2790 Minimum Time: 1366 Maximum Time: 292003 Overhead: 2 (Calculated but not removed) Attention: The TIMEUSED function is not eligible for zAAP. When in profiling or debug mode this may not be a problem, but when you use this function for logging purposes you should keep this in mind. 5.5 Elimination analysis The following definitions are important for a complete understanding of this topic: Internal Throughput Rate or ITR This is the number of units of work accomplished per unit of processor busy time in an unconstrained environment. Internal Throughput Rate = Units of Work / Processor Time Consumed External Throughput Rate or ETR This is the number of units of work accomplished per unit of elapsed time including the elapsed time of external resources. External Throughput Rate = Units of Work / Elapsed Time In many cases a Java application will make synchronous requests to external resources. Some of these calls may involve network communications out of the machine where the application is running. External calls, especially in test environments, can have extremely variable response times that will lead to different transaction times for the Java application making the calls. Therefore, it can be difficult to gain a true picture of the performance of an application when presented with this variability. One could use broader statistical techniques to calculate the ETR and ITR of an application, but in many cases a deeper understanding of the performance of an application can be gained, and issues exposed, by driving it to its limits. This can be difficult if synchronous calls to external resources limit throughput. A technique to establish the base performance of a transaction that could include variable external requests is to simply eliminate them by replacing the calls with methods that simulate the response from the original resource. For example, if Chapter 5. Measuring performance and application profiling 111