Registry / workflow / pykka
library4.4.2pypypi✓ verified 86d ago

Pykka is a Python implementation of the actor model, providing concurrency primitives for building distributed and concurrent systems. Version 4.4.2 runs on Python >=3.10. New releases are sporadic.

pip install pykka
INSTALL
IMPORT
SIG · PYKKA
P
pykka
workflowpythonv4.4.2
Install
1.6s avg
Import
61ms
Disk
16MB
Pass rate
10/ 10
Env Coverage10 / 10
glibc
3.93.13
musl
3.93.13
Install & Compatibility
Where this runs
tested against v4.4.2 · pip install
no network on importno background threads
Install × environment matrix
Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux
musl
py 3.103.95 runs
installs and imports cleanly · install 0.0s · import 0.062s · 18MB
glibc
py 3.103.95 runs
installs and imports cleanly · install 1.6s · import 0.060s · 18MB
16MB installed
● package 16MB
Code
Verified usage

Verified import paths — ran on the pinned version, not inferred.

Actor
from pykka import Actor
Standard import
ThreadingActor
from pykka import ThreadingActor
Preferred for I/O-bound tasks
ActorRef
from pykka import ActorRef
Reference to an actor instance
ActorRegistry
from pykka import ActorRegistry
Global registry of actors
getattr
from pykka import getattr
from pykka.actor import getattr
getattr moved to top-level since v3

Define an actor class, start it, send a message, and stop.

import pykka class Greeter(pykka.ThreadingActor): def __init__(self, greeting='Hi'): super().__init__() self.greeting = greeting def on_receive(self, message): return f'{self.greeting}, {message}' actor = Greeter.start(greeting='Hello').proxy() print(actor.on_receive('World').get()) # Hello, World actor.stop()
Debug
Known issues
gotchaActors are not threadsafe; avoid sharing mutable state between actors. Use message passing only.
fix
Design actors as isolated units communicating via messages (dicts or immutable objects).
affects: all
gotchaUnlike the standard library, Pykka actors must be stopped explicitly to release resources. ActorRegistry will not clean them up automatically.
fix
Call actor.stop() or use a context manager: with Greeter.start() as actor: ...
affects: >=3.0
breakingIn Pykka 4.x, on_receive must return a value or raise an exception; previously None was allowed and would cause hangs.
fix
Ensure on_receive always returns a value (or call actor.stop() explicitly without a return).
affects: 4.0 - 4.4
gotchaProxy() and get() are blocking. Using them inside an actor's on_receive can cause deadlocks.
fix
Use future.get() only outside actors, or use call() with a callback instead.
affects: all
Errors
Common errors & fixes
ModuleNotFoundError: No module named 'pykka'
Pykka not installed or wrong Python environment.
fix
Install with 'pip install pykka' and verify Python version >=3.10.
AttributeError: 'MyActor' object has no attribute 'start'
Attempting to call start() on an instance instead of the class.
fix
Use MyActor.start() (class method) not my_actor.start().
TimeoutError: Actor call timed out after ... seconds
Actor's on_receive never returned a value (or deadlocked).
fix
Ensure every on_receive returns a result. If no result, call actor.stop() and return a default.
Upgrade
Version history
4.4.2latest on PyPI · released Mar 14, 2026
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Dependencies

No dependency data recorded yet.

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Resources
pykka — pip install pykka · libregistry