Using Tenacity: A Python Retry Library – Installation, Unlimited Retries, Stop Conditions, Intervals, and Logging

Tenacity is an Apache‑2.0 licensed, Python‑based generic retry library that simplifies adding retry behavior to many tasks, such as re‑running test cases, crawling scripts, or ticket‑booking attempts.

Installation

<code>pip install Tenacity</code>

Unlimited Retry

<code>from tenacity import retry

@retry()
def test_retry():
    print('失败重试中')
    raise Exception

test_retry()</code>

Stop After Success

<code>from tenacity import retry
import random

@retry()
def test_retry():
    if random.randint(0, 10) > 1:
        print('失败重试中')
        raise Exception
    else:
        print('成功')

test_retry()</code>

Limit Number of Attempts

<code>from tenacity import retry, stop_after_attempt
import random

@retry(stop=stop_after_attempt(7))
def test_retry():
    print('失败重试中')
    raise Exception

test_retry()</code>

Limit Total Retry Time

<code>from tenacity import retry, stop_after_delay
import random, time

@retry(stop=stop_after_delay(3))
def test_retry():
    time.sleep(1)
    print('失败重试中')
    raise Exception

test_retry()</code>

Combine Stop Conditions

<code>from tenacity import retry, stop_after_attempt, stop_after_delay
import random, time

@retry(stop=stop_after_delay(3) | stop_after_attempt(2))
def test_retry():
    time.sleep(1)
    print('失败重试中')
    raise Exception

test_retry()</code>

Fixed Retry Interval

<code>from tenacity import retry, wait_fixed
import random, time

@retry(wait=wait_fixed(2))
def test_retry():
    print('失败重试中')
    print(time.ctime())
    raise Exception

test_retry()</code>

Random Retry Interval

<code>from tenacity import retry, wait_random
import random, time

@retry(wait=wait_random(min=1, max=2))
def test_retry():
    print('失败重试中')
    print(time.ctime())
    raise Exception

test_retry()</code>

Log Before Each Retry

<code>from tenacity import retry, stop_after_attempt, before_log
import logging, sys

logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)
logger = logging.getLogger(__name__)

@retry(stop=stop_after_attempt(3), before=before_log(logger, logging.DEBUG))
def test_retry():
    print('失败重试中')
    raise Exception('Fail')

test_retry()</code>

Log After Each Retry

<code>from tenacity import retry, stop_after_attempt, after_log
import logging, sys

logging.basicConfig(stream=sys.stderr, level=logging.DEBUG)
logger = logging.getLogger(__name__)

@retry(stop=stop_after_attempt(3), after=after_log(logger, logging.DEBUG))
def test_retry():
    print('失败重试中')
    raise Exception('Fail')

test_retry()</code>

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