Slow does this by taking advantage of two signals, SIGSTOP and SIGCONT, which respectively stop and re-start a unix process’ execution.

I’ve used this tool to prevent long-running cpu-bound processes from consuming an entire cpu to improve performance of other processes on the machine. I’ve also used it to slow part of a two-part data import process where temporary data files could be created much faster than they could be processed and removed, running the risk of low disk space conditions.

Slow is released under the GPL v3. For documentation, more information, and download links for slow and its source code, please see slow’s web page.