Circus is a program that runs and watches several processes.

Circus can be used as a library or through the command line.

Circus provides high-level Classes and functions that will let you run processes. For example, if you just want to run 4 workers forever, you can write:

from circus import get_trainer

trainer = get_trainer("myprogram", 3)
try:
    trainer.start()
finally:
    trainer.stop()

This snippet will run 3 myprogram processes and watch them for you.

See http://packages.python.org/circus for a full Library documentation.

Circus provides a command line script that can be used to run one or several types of processes.

It's an ini-style like file. Example:

[circus]
check_delay = 5
endpoint = tcp://127.0.0.1:5555

[show:myprogram]
cmd = python
args = -u myprogram.py $WID
warmup_delay = 0
num_flies = 5

The file is then run using circusd:

$ circusd example.ini

There's also a circusctl command line tool to query Circus to perform actions like adding or removing workers, or getting back some statistics.

See http://packages.python.org/circus for a full documentation on the configuration file and the commands options.

You can reach us for any feedback, bug report, or to contribute, at https://github.com/mozilla-services/circus