PYTHON-5528 & PYTHON-5651 Add exponential backoff to operation retry loop for server overloaded errors #2635
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…r overloaded errors (cherry picked from commit 95948d3def875f1efb4d912ab8f507f518604ef5)
(cherry picked from commit ebf65519f12d160da6d2088c22f6c69fad5a37d0)
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(cherry picked from commit 3093a7c)
blink1073
changed the title
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blink1073
requested review from
Jibola,
NoahStapp and
sleepyStick
and removed request for
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NoahStapp
requested changes
Feb 2, 2026
| await change_stream._initialize_cursor() | ||
| return change_stream | ||
|
|
||
| async def _conn_for_writes( |
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What's the motivation behind the change from this centralized method to a bunch of def inner closures?
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Because we needed to pass a function to the retry helper class, and the logic for backpressure is centralized there
| # If we need to apply backpressure to the first command, | ||
| # we will need to revert back to starting state. | ||
| if self._session is not None and self._session.in_transaction: | ||
| self._session._transaction.has_completed_command = True |
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How does being in a transaction here imply that the transaction has completed a command?
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Because we've just recorded a successful read
sleepyStick
reviewed
Feb 2, 2026
pymongo/asynchronous/mongo_client.py
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2807
| always_retryable = exc.has_error_label( | ||
| "RetryableError" | ||
| ) and exc.has_error_label("SystemOverloadedError") | ||
| overloaded = exc.has_error_label("SystemOverloadedError") |
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minor thought but it might be a smidge easier to read if it was like:
overloaded = exc.has_error_label("SystemOverloadedError")
always_retryable = exc.has_error_label("RetryableError") and overloaded
…-python-driver into PYTHON-5528-backpressure
NoahStapp
approved these changes
Feb 3, 2026
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PYTHON-5528
PYTHON-5651
Summary
Adds unified and prose tests from mongodb/specifications#1862 and replaces the use of the
_retry_overloadwith the retry helper method calls to ensure that servers are properly deprioritized. They needed to be done together to verify that the unified tests still work.Changes in this PR
_retry_overloadwith the retry helper method calls to ensure that servers are properly deprioritizedTesting Plan
Added unified and prose tests, testing as part of PR.
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