May 26, 2018
Run tests in parallel at high frequency
hfm is an application to run tests in parallel at a high frequency. If the outcome of the test results in a state change, other commands can be executed.
It is designed to be a general purpose, loosely-coupled tool, by having both the tests and the state change commands be executed by the operating system. For example, one could write the test in shell or c, and have it called through the exec facility.
In practice, the overhead of spawning a new process per test limits frequency that can be achieved by the tests, and their results. Anecdotally, 5ms intervals have been seen to be achievable.
An example application is to poll other network services for health, and to take actions based on their health status changes.