Easy to use retry decorator

0.9.2 · abandoned · verified Sat Mar 28

The `retry` library (version 0.9.2) provides a simple decorator for adding retry logic to Python functions. It allows configuration of exceptions to catch, number of attempts, delay between retries, backoff strategy, and optional jitter. This library is largely unmaintained, with its last release in 2016, and is superseded by more actively developed alternatives like `tenacity`.

Warnings

breaking This 'retry' library (invl/retry) is largely unmaintained, with its last release in 2016. Its API is not compatible with 'tenacity', which is the actively maintained successor to the 'retrying' library (another distinct, unmaintained project).
Fix: Consider migrating to `tenacity` (pip install tenacity) for active development, better features, and bug fixes. Tenacity offers a more robust and flexible API for retry strategies.
gotcha By default, the `@retry` decorator will retry indefinitely if the `tries` parameter is not explicitly set or set to -1.
Fix: Always set a finite `tries` value (e.g., `tries=5`) or a `max_delay` to prevent infinite loops in production environments.
gotcha The `retry` decorator does not inherently support asynchronous functions (async/await syntax).
Fix: For asynchronous code, you will need to use a different retry library that explicitly supports `async/await`, such as `tenacity` with `AsyncRetrying` or `stamina`.
gotcha When using `jitter`, if a tuple `(min, max)` is provided, the extra delay is chosen randomly. If a single number is provided, the jitter is fixed.
Fix: Be aware of the type of `jitter` parameter passed. For true random jitter to prevent 'thundering herd' problems, provide a tuple (e.g., `jitter=(0, 1)`).

Install

pip install retry Install stable version

Imports

retry
```
from retry import retry
```
The 'retrying' library is a different, also unmaintained, project that `tenacity` forked from. This `retry` library has a distinct import path.

Quickstart

This quickstart demonstrates how to apply the `@retry` decorator to a function, configuring it to retry on specific exceptions, with a maximum number of attempts, an initial delay, exponential backoff, and a maximum delay between retries. It will print logging messages for each retry attempt.

import random
from retry import retry
import logging

logging.basicConfig(level=logging.INFO)

@retry(exceptions=(IOError, ValueError), tries=3, delay=2, backoff=2, max_delay=10)
def unreliable_function():
    if random.randint(0, 5) > 2:
        raise IOError("Simulated network error")
    elif random.randint(0, 5) < 1:
        raise ValueError("Simulated data error")
    else:
        print("Function succeeded!")
        return "Success"

try:
    result = unreliable_function()
    print(f"Final result: {result}")
except (IOError, ValueError) as e:
    print(f"Function failed after all retries: {e}")

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