PYTHON-5504 Prototype exponential backoff in with_transaction #2492

Original file line number	Diff line number	Diff line change
Expand Up		@@ -135,7 +135,9 @@

		from __future__ import annotations

	import asyncio
		import collections
	import random
		import time
		import uuid
		from collections.abc import Mapping as _Mapping
Expand Down Expand Up		@@ -471,6 +473,8 @@ def _max_time_expired_error(exc: PyMongoError) -> bool:
		# This limit is non-configurable and was chosen to be twice the 60 second
		# default value of MongoDB's `transactionLifetimeLimitSeconds` parameter.
		_WITH_TRANSACTION_RETRY_TIME_LIMIT = 120
	_BACKOFF_MAX = 1
	_BACKOFF_INITIAL = 0.050 # 50ms initial backoff


		def _within_time_limit(start_time: float) -> bool:
Expand Down Expand Up		@@ -700,7 +704,13 @@ async def callback(session, custom_arg, custom_kwarg=None):
		https://github.com/mongodb/specifications/blob/master/source/transactions-convenient-api/transactions-convenient-api.md#handling-errors-inside-the-callback
		"""
		start_time = time.monotonic()
	retry = 0
		while True:
	if retry: # Implement exponential backoff on retry.
	jitter = random.random() # noqa: S311
	backoff = jitter * min(_BACKOFF_INITIAL * (2**retry), _BACKOFF_MAX)
	await asyncio.sleep(backoff)
	retry += 1
		await self.start_transaction(
		read_concern, write_concern, read_preference, max_commit_time_ms
		)
Expand Down

9 changes: 9 additions & 0 deletions pymongo/synchronous/client_session.py

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Original file line number	Diff line number	Diff line change
Expand Up		@@ -136,6 +136,7 @@
		from __future__ import annotations

		import collections
	import random
		import time
		import uuid
		from collections.abc import Mapping as _Mapping
Expand Down Expand Up		@@ -470,6 +471,8 @@ def _max_time_expired_error(exc: PyMongoError) -> bool:
		# This limit is non-configurable and was chosen to be twice the 60 second
		# default value of MongoDB's `transactionLifetimeLimitSeconds` parameter.
		_WITH_TRANSACTION_RETRY_TIME_LIMIT = 120
	_BACKOFF_MAX = 1
	_BACKOFF_INITIAL = 0.050 # 50ms initial backoff


		def _within_time_limit(start_time: float) -> bool:
Expand Down Expand Up		@@ -699,7 +702,13 @@ def callback(session, custom_arg, custom_kwarg=None):
		https://github.com/mongodb/specifications/blob/master/source/transactions-convenient-api/transactions-convenient-api.md#handling-errors-inside-the-callback
		"""
		start_time = time.monotonic()
	retry = 0
		while True:
	if retry: # Implement exponential backoff on retry.
	jitter = random.random() # noqa: S311
	backoff = jitter * min(_BACKOFF_INITIAL * (2**retry), _BACKOFF_MAX)
	time.sleep(backoff)
	retry += 1
		self.start_transaction(read_concern, write_concern, read_preference, max_commit_time_ms)
		try:
		ret = callback(self)
Expand Down

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