Distributed

1.0

Class SchedulerPlugin

Interface to extend the Scheduler

Declaration

class SchedulerPlugin
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Documentation

The scheduler operates by triggering and responding to events like
``task_finished``, ``update_graph``, ``task_erred``, etc..

A plugin enables custom code to run at each of those same events.  The
scheduler will run the analogous methods on this class when each event is
triggered.  This runs user code within the scheduler thread that can
perform arbitrary operations in synchrony with the scheduler itself.

Plugins are often used for diagnostics and measurement, but have full
access to the scheduler and could in principle affect core scheduling.

To implement a plugin implement some of the methods of this class and add
the plugin to the scheduler with ``Scheduler.add_plugin(myplugin)``.

Examples

>>> class Counter(SchedulerPlugin):
...     def __init__(self):
...         self.counter = 0
...
...     def transition(self, key, start, finish, *args, **kwargs):
...         if start == 'processing' and finish == 'memory':
...             self.counter += 1
...
...     def restart(self, scheduler):
...         self.counter = 0

>>> plugin = Counter()
>>> scheduler.add_plugin(plugin)  # doctest: +SKIP

Methods

Subclasses

Reexports

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