Last week while I tested a new Web Service I forgot to stress test the service.
We figures out that if it could cope with 50 concurrent call that would be more than it will ever be stressed in real life, so I run a test with 100 concurrent calls. This is how i did it:
The XML tag <forevery rows='100' parallel='yes'/> iterates the job 100 times in parallel.
It took 4 seconds to do that: start the job, create 100 threads, call the web service, receive a result, write it to disk and finally cleanup.
The execution of this ITL workflow is done in PHP including the parallel scheduling of the job 100 times. Much of the 4 seconds are probably PHP execution and server communication. The web service is more stress resistant than we will ever need.