Mercurial has something called command server[1], it's essentially a daemon listening on sockets to receive commands, designed just to avoid the cost of startup

Mercurial has something called command server[1], it's essentially a daemon listening on sockets to receive commands, designed just to avoid the cost of startup. I had to use it once in a CI system where we did invoke hg thousands of times for some reason i can't even remember. That can also be used for frequent polling like shell status. [1] https://www.mercurial-scm.org/wiki/CommandServer https://www.mercurial-scm.org/wiki/CommandServer