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tenacity 9.1.4: Retry a flaky call with backoff and give up on the errors that will never succeed

Verifiziertes Beispiel für pypi tenacity 9.1.4: Retry a flaky call with backoff and give up on the errors that will never succeed. Der Vertrag lief auf…

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Ausführungsbelege

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Beleggrundlage
Signierter Vertrag bestanden
Verifizierungsbelege
2
Signaturschlüssel, die es gebaut haben
2
Deklarierte Umgebung python 3.12 linux x64 python 3.12 python pip

Umgebungen der Verifizierungsläufe

Umgebung Contract Stufen Lauf
python 3.12 · linux alpine/x64 · docker ed25519:a2ec939a4c60e243 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · python@1		 2026-08-13
python 3.12 · linux alpine/x64 · docker ed25519:d91480838ac982c9 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · python@1		 2026-08-17

Fall

HOW
Ziel
Retry a flaky call with backoff and give up on the errors that will never succeed
Pakete
Symbole
  • retry
  • stop_after_attempt
  • wait_fixed
  • retry_if_exception_type
Umgebung
python 3.12
Erstellt
2026-08-13T18:43:56Z

Contract

  1. retry a function that fails twice then succeeds
  2. assert it was called exactly three times
  3. assert an exception type outside the retry filter is raised immediately
  4. assert exhausting the attempts raises RetryError carrying the last failure

Dateien

  • csx.json
  • requirements.txt
  • src/__init__.py
  • src/retry.py
  • test/contract.py

Quellartefakt herunterladen (tar.gz)

Quelltext

csx.json
{"case":{"caseId":"case:sha256:e95b2d65f45ae3869f087aecfeddb905091f9762f83d3fa54d854f75fc95257a","constraints":{"runtime":"python"},"contract":["retry a function that fails twice then succeeds","assert it was called exactly three times","assert an exception type outside the retry filter is raised immediately","assert exhausting the attempts raises RetryError carrying the last failure"],"goal":"Retry a flaky call with backoff and give up on the errors that will never succeed","kind":"HOW","packages":["pkg:pypi/tenacity@9.1.4"],"schemaVersion":1,"symbols":["retry","stop_after_attempt","wait_fixed","retry_if_exception_type"]},"contractCommand":["python","test/contract.py"],"environment":{"arch":"x64","ecosystem":"pypi","executionContext":"python","language":"python","os":"linux","packageManager":"pip","runtime":"python","runtimeVersion":"3.12","schemaVersion":1},"license":"MIT-0","packages":["pkg:pypi/tenacity@9.1.4"],"schemaVersion":1,"symbols":["retry","stop_after_attempt","wait_fixed","retry_if_exception_type"],"verifierAdapter":"python@1"}
requirements.txt
tenacity==9.1.4
src/__init__.py
src/retry.py
"""Bounded retries with tenacity."""

from tenacity import (
    retry,
    retry_if_exception_type,
    stop_after_attempt,
    wait_fixed,
)


class Transient(Exception):
    """Worth retrying: a timeout, a 503, a dropped connection."""


class Permanent(Exception):
    """Never worth retrying: bad credentials, a 400, a missing table."""


def make_flaky(fail_times, error=Transient):
    calls = {"n": 0}

    @retry(
        # Without retry=, tenacity retries EVERY exception, which turns a
        # permanent failure into the same failure N times and N times slower.
        retry=retry_if_exception_type(Transient),
        stop=stop_after_attempt(3),
        wait=wait_fixed(0.01),
    )
    def call():
        calls["n"] += 1
        if calls["n"] <= fail_times:
            raise error("attempt %d" % calls["n"])
        return "ok"

    return call, calls
test/contract.py
import os
import sys

sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
from tenacity import RetryError

from src.retry import Permanent, Transient, make_flaky

# Fails twice, succeeds on the third attempt.
call, calls = make_flaky(2)
assert call() == "ok"
assert calls["n"] == 3, calls

# A permanent error is not retried: raised on the first attempt.
call, calls = make_flaky(5, error=Permanent)
try:
    call()
except Permanent:
    pass
else:
    raise AssertionError("a non-retryable error must propagate immediately")
assert calls["n"] == 1, calls

# Exhausting the attempts raises RetryError wrapping the last failure.
call, calls = make_flaky(99)
try:
    call()
except RetryError as exc:
    assert calls["n"] == 3, calls
    assert isinstance(exc.last_attempt.exception(), Transient)
else:
    raise AssertionError("exhausted retries must raise RetryError")

print("CONTRACT PASS: tenacity retried only what it was told to, three times")

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