Process supervision

Process supervision is a form of operating system service management in which some master process remains the parent of the service processes.

Benefits

Benefits^[1] compared to traditional process launchers and system boot mechanisms, like System V init, include:

• Ability to restart services which have failed
• The fact that it does not require the use of "pidfiles"
• Clean process state
• Reliable logging, because the master process can capture the stdout/stderr of the service process and route it to a log
• Faster (concurrent) and ability to start up and stop

Implementations

• daemontools
• daemontools-encore: Derived from the public-domain release of daemontools
• Eye: A Ruby implementation
• Finit: Fast, Extensible Init for Linux Systems
• God: A Ruby implementation
• immortal: A Go implementation
• PM2: A Process Manager for Node.js
• Initng
• launchd
• minit: A small, yet feature-complete Linux init
• Monit
• runit
• Supervisor: A Python implementation
• s6: Low-level process and service supervision
• Systemd

References