orphanage 0.1.0

Description:

orphanage 0.1.0

Let child processes in Python suicide if they became orphans.

Installation
pip install orphanage
Don’t forget to put it in setup.py / requirements.txt.


Usage
from orphanage import exit_when_orphaned

exit_when_orphaned()


Motivation
Some application server softwares (e.g. Gunicorn) work on a multiple-process
architect which we call the master-worker model. They must clean up the worker
processes if the master process is stopped, to prevent them from becoming
orphan processes.
In the gevent-integration scene, the worker processes of Gunicorn poll their
ppid in an user thread (a.k.a greenlet) to be orphan-aware. But the user
thread may be hanged once the master process crashed because of the blocked
writing on a pipe, the communicating channel between master process and
worker processes.
We want to perform this ppid polling in a real kernel thread. That is the
intent of this library.


Principle
This library spawns an internal thread to poll the ppid at regular
intervals (for now it is one second). Once the ppid changed, the original
parent process should be dead and the current process should be orphaned. The
internal thread will send SIGTERM to the current process.
In the plan, the prctl & SIGHUP pattern may be introduced in Linux
platforms to avoid from creating threads. For now, the only supported strategy
is the ppid polling, for being portable.


Alternatives
CaoE is an alternative to this library which developed by the Douban Inc. It
uses prctl and a twice-forking pattern. It has a pure Python implementation
without any C extension compiling requirement. If you don’t mind to twist the
process tree, that will be a good choice too.


Contributing
If you want to report bugs or request features, please feel free to open
issues on GitHub.
Of course, pull requests are always welcome.