Why should I use Circus instead of X ?

  1. Circus simplifies your web stack process management

    Circus knows how to manage processes and sockets, so you don’t have to delegate web workers managment to a WGSI server.

    See Circus stack v.s. Classical stack

  2. Circus provides pub/sub and poll notifications via ZeroMQ

Circus has a pub/sub channel you can subscribe to. This channel receives all events happening in Circus. For example, you can be notified when a process is flapping, or build a client that triggers a warning when some processes are eating all the CPU or RAM.

These events are sent via a ZeroMQ channel, which makes it different from the stdin stream Supervisord uses:

  • Circus sends events in a fire-and-forget fashion, so there’s no need to manually loop through all listeners and maintain their states.
  • Subscribers can be located on a remote host.

Circus also provides ways to get status updates via one-time polls on a req/rep channel. This means you can get your information without having to subscribe to a stream. The Command-line tools command provided by Circus uses this channel.

See Step-by-step tutorial.

  1. Circus is (Python) developer friendly

While Circus can be driven entirely by a config file and the circusctl / circusd commands, it is easy to reuse all or part of the system to build your own custom process watcher in Python.

Every layer of the system is isolated, so you can reuse independently:

  • the process wrapper (Process)
  • the processes manager (Watcher)
  • the global manager that runs several processes managers (Arbiter)
  • and so on…
  1. Circus scales
One of the use cases of Circus is to manage thousands of processes without adding overhead – we’re dedicated to focus on this.