The default threading runtime has no dependencies other than Pykka itself and the Python standard library.


class pykka.ThreadingFuture[source]

Implementation of Future for use with regular Python threads`.

The future is implemented using a queue.Queue.

The future does not make a copy of the object which is set() on it. It is the setters responsibility to only pass immutable objects or make a copy of the object before setting it on the future.

Changed in version 0.14: Previously, the encapsulated value was a copy made with copy.deepcopy(), unless the encapsulated value was a future, in which case the original future was encapsulated.

get(*, timeout: float | None = None) Any[source]

Get the value encapsulated by the future.

If the encapsulated value is an exception, it is raised instead of returned.

If timeout is None, as default, the method will block until it gets a reply, potentially forever. If timeout is an integer or float, the method will wait for a reply for timeout seconds, and then raise pykka.Timeout.

The encapsulated value can be retrieved multiple times. The future will only block the first time the value is accessed.


timeout (float or None) – seconds to wait before timeout


pykka.Timeout if timeout is reached


encapsulated value if it is an exception


encapsulated value if it is not an exception

set(value: Any | None = None) None[source]

Set the encapsulated value.


value (any object or None) – the encapsulated value or nothing


an exception if set is called multiple times

set_exception(exc_info: OptExcInfo | None = None) None[source]

Set an exception as the encapsulated value.

You can pass an exc_info three-tuple, as returned by sys.exc_info(). If you don’t pass exc_info, sys.exc_info() will be called and the value returned by it used.

In other words, if you’re calling set_exception(), without any arguments, from an except block, the exception you’re currently handling will automatically be set on the future.


exc_info (three-tuple of (exc_class, exc_instance, traceback)) – the encapsulated exception

class pykka.ThreadingActor(*_args: Any, **_kwargs: Any)[source]

Implementation of Actor using regular Python threads.

use_daemon_thread: ClassVar[bool] = False

A boolean value indicating whether this actor is executed on a thread that is a daemon thread (True) or not (False). This must be set before pykka.Actor.start() is called, otherwise RuntimeError is raised.

The entire Python program exits when no alive non-daemon threads are left. This means that an actor running on a daemon thread may be interrupted at any time, and there is no guarantee that cleanup will be done or that pykka.Actor.on_stop() will be called.

Actors do not inherit the daemon flag from the actor that made it. It always has to be set explicitly for the actor to run on a daemonic thread.