upcache 0.2.5

In-memory cache with multiprocessing support

Introduction

UpCache is a pure Python cache with multiprocessing support.

Most Python cache frameworks require external services such as Memcached or Redis which require setup and maintenance. UpCache tries to ameliorate the process of creating a shared cache for multiprocessing workers such as those found in WSGI applications.

Getting Started

Using UpCache requires at least one instance of UpCache to remain open and available for contents to be preserved between worker processes.

Sample code provided will create a key-value pair in one process and allows another process to access it:

from multiprocessing import Process
from upcache import UpCache
import time

def worker1(name: str) -> None:
    cache = UpCache(name)
    cache.set(b'Light Entertainment Awards', b'Dickie Attenborough')
    cache.close()

def worker2(name: str) -> None:
    cache = UpCache(name)
    time.sleep(1)
    print(cache.get(b'Light Entertainment Awards'))
    cache.close()

if __name__ == '__main__':
    cache_name = 'TVHosts'
    p1 = Process(target=worker1, args=(cache_name,))
    p2 = Process(target=worker2, args=(cache_name,))

    p1.start()
    p2.start()

    p1.join()
    p2.join()

Architecture

UpCache spawns an internally-hosted TCP server which facilitates inter-process communication and provides a synchronized in-memory key-value store.

To avoid overlapping TCP servers from spawning when using UpCache, the library creates an exclusive connection file to claim ownership as the process to spawn the TCP server. Once the TCP server begins running on an ephemeral port, it writes the connection info into the connection file for all UpCache clients to connect to the TCP server for the key-value store.

UpCache clients are typically shared per cache per process to avoid heavy resource contention (one client equals one TCP socket).

Once all clients disconnect, the UpCache TCP server shuts down and disposes of all contents (both the in-memory key-value store and connection file).

Features

UpCache supports the following:

• Basic key operations (get/set/drop, increment/decrement, clear, count, keys, items)
• Waiting for key events
• Subscriptions to key events