justbackoff

A simple backoff algorithm for Python 3.7+.

Install

$ pip install justbackoff

Usage

Backoff is a counter. It starts at min_ms. After every call to duration(), it is multiplied by factor. It is capped at max_ms. It returns to min_ms on every call to reset(). jitter adds randomness (see below).

---

Simple example

from justbackoff import Backoff

b = Backoff(min_ms=100, max_ms=10000, factor=2, jitter=False)

print(b.duration())
print(b.duration())
print(b.duration())

print("Reset!")
b.reset()

print(b.duration())

0.1
0.2
0.4
Reset!
0.1

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Example using socket package

import socket
import time

from justbackoff import Backoff


sock = socket.socket()
b = Backoff()

while True:
    try:
        sock.connect(("127.0.0.1", 1337))
    except Exception as e:
        d = b.duration()
        print("{}, reconnecting in {} seconds".format(e, d))
        time.sleep(d)
        continue

    b.reset()
    sock.send("Hello, world!")
    sock.close()

---

Example using jitter

Enabling jitter adds some randomization to the backoff durations. See Amazon’s writeup of performance gains using jitter. Seeding is not necessary but doing so gives repeatable results.

import random

from justbackoff import Backoff

b = Backoff(min_ms=100, max_ms=10000, factor=2, jitter=True)

random.seed(42)

print(b.duration())
print(b.duration())
print(b.duration())

print("Reset!")
b.reset()

print(b.duration())
print(b.duration())
print(b.duration())

0.1
0.102501075522
0.182508795511
Reset!
0.1
0.173647121416
0.303009846227

Credits

Ported from Go backoff