Concurrency Testing

Concurrency testing determines what happens when similar or identical transactions execute at the same time and try to perform the same task, such as processing the same file or data base record.

Manual concurrency testing is virtually impossible. You would have to have multiple users simultaneously enter the same transaction on different terminals. Even if that were practical, network and access method processing would affect how CICS processes the transactions. With CA Verify for VTAM, however, concurrency testing is both easy and accurate because CA Verify for VTAM automatically ensures that the transactions are processed concurrently.

Follow these steps:

Create a test stream by logging the screens when a transaction updates an inventory file. Or, use an existing test stream.
Merge the test stream with itself. The new test stream consists of two identical sets of records, each assigned to a different terminal. If necessary, you can merge the new test stream with itself again, creating four identical sets of records assigned to four terminals.
Optionally, you can edit the test stream to alter the test data. For example, you may want to alter the inventory file key to ensure that the test stream updates different records. You can edit the test stream by copying it before the merge, editing one test stream, and then merging the two test streams. Or, you can first create the merged test stream and then edit it.
Run the merged test stream.
- CA Verify for VTAM sends the first input screen from terminal 1 to the application. Then, CA Verify for VTAM sends the first input screen from terminal 2 to the application. These are, of course, identical screens unless you edited one.
- Next, the application sends the first output screen from the application to terminal 1. Then, the application sends the first output screen from the application to terminal 2.
- CA Verify for VTAM continues to run the test stream. You can easily determine how the application concurrently processes these requests.

When CA Verify for VTAM runs a single terminal test stream that has been merged into itself, it ensures that all output screens are received by the terminals before it sends the next input screens. Using this method, a multiple terminal test stream always produces consistent results.

The following diagrams illustrate two ways in which you can edit the test stream: