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Type: Spec Change
Resolution: Unresolved
Priority: Unknown
Fix Version/s: None
Component/s: Retryability
Labels:
- availability-prevent-drivers

Epic Link:
Client Backpressure Spec
Driver Changes:
Needed
Quarter:
- FY26Q2
- FY26Q3
- FY26Q4
Downstream Changes Summary:
Hide

Summary of necessary driver changes

Implement the new backpressure retry logic detailed in https://github.com/mongodb/specifications/blob/client-backpressure/source/client-backpressure/client-backpressure.md.

Add opt-in token bucket support with the new adaptiveRetries URI and client option listed in https://github.com/mongodb/specifications/blob/client-backpressure/source/uri-options/uri-options.md.

Commits for syncing spec/prose tests
(and/or refer to an existing language POC if needed)

https://github.com/mongodb/specifications/commit/1125200e4a6161d87cb5090860597eb8e8e90bf1

Context for other referenced/linked tickets
Show
Summary of necessary driver changes Implement the new backpressure retry logic detailed in https://github.com/mongodb/specifications/blob/client-backpressure/source/client-backpressure/client-backpressure.md . Add opt-in token bucket support with the new adaptiveRetries URI and client option listed in https://github.com/mongodb/specifications/blob/client-backpressure/source/uri-options/uri-options.md . Commits for syncing spec/prose tests (and/or refer to an existing language POC if needed) https://github.com/mongodb/specifications/commit/1125200e4a6161d87cb5090860597eb8e8e90bf1 Context for other referenced/linked tickets

Driver Compliance:

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Key	Status/Resolution	FixVersion
CDRIVER-6092	In Code Review
CXX-3342	Backlog
CSHARP-5723	In Code Review
GODRIVER-3658	Backlog
JAVA-5956	Backlog
NODE-7142	In Progress
PYTHON-5528	Done
PHPLIB-1719	Blocked
RUBY-3706	Ready for Work
RUST-2273	In Progress

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As part of DRIVERS-3160 Client Backpressure, we plan to make retry loops use exponential backoff and jitter to reduce the load on the server and improve goodput. Retryable reads and writes only retry once by default but can perform multiple when CSOT is enabled. The convenient transaction api (DRIVERS-1934) will also retry multiple times. These retry loops should share a common backoff and jitter policy.

We also add an adaptive token bucket to limit load amplification during peak overload. Each time a client makes a successful request (ok:1 or a successful error like DuplicateKeyError) it deposits a fractional “token” into a bucket. Each time a request fails (ok:0 with SystemOverloaded error), the client performs retries as normal (with exponential backoff + jitter) as long as there are whole tokens available in the bucket. This approach establishes a limited memory for the operational conditions of the upstream service: if there are tokens available for retry, then the service has been healthy recently.

blocks

SERVER-114889 Unify mongos overload retry logic with the Client Backpressure Specification

Blocked

has to be finished together with

DRIVERS-3326 Clarify `NoWritesPerformed` error label behavior when multiple retries occur

Implementing

is depended on by

PYTHON-5668 Merge backpressure branch into mainline

Blocked

is duplicated by

DRIVERS-3240 Adaptive token bucket retry policy

Closed

is related to

DRIVERS-3160 Client Backpressure Support

In Progress

DRIVERS-3352 Add RetryableError labels to retryability eligibility for retryable reads/writes

Backlog

PYTHON-5505 Prototype system overload retry loop for all operations

Closed

DRIVERS-3412 Fix client construction in backpressure unified tests

Implementing

DRIVERS-3411 Transaction state is preserved across retries

Implementing

related to

SERVER-108583 Add diagnostic metadata to identify retried commands

Backlog

DRIVERS-3332 [ds-19.21] [Drivers] Admission-control integration (client behavior: backoff+jitter; bounded retries; circuit breakers)

Closed

SERVER-114889 Unify mongos overload retry logic with the Client Backpressure Specification

Blocked

DRIVERS-3241 Add diagnostic metadata to retried commands

Blocked

DRIVERS-1934 withTransaction API retries too frequently

Implementing

split to

CXX-3342 Exponential backoff and jitter in retry loops

Backlog

GODRIVER-3658 Exponential backoff and jitter in retry loops

Backlog

JAVA-5956 Exponential backoff and jitter in retry loops

Backlog

PHPLIB-1719 Exponential backoff and jitter in retry loops

Blocked

CDRIVER-6092 Exponential backoff and jitter in retry loops

In Code Review

CSHARP-5723 Exponential backoff and jitter in retry loops

In Code Review

RUBY-3706 Exponential backoff and jitter in retry loops

Ready for Work

NODE-7142 Exponential backoff and jitter in retry loops

In Progress

RUST-2273 Exponential backoff and jitter in retry loops

In Progress

PYTHON-5528 Exponential backoff and jitter in retry loops

Closed

(4 is related to, 5 related to, 10 split to)

Assignee:: Noah Stapp
Reporter:: Shane Harvey
Engineering Lead:: Jib Adegunloye
Votes:: 0 Vote for this issue
Watchers:: 3 Start watching this issue

Created:: Jul 31 2025 08:32:31 AM UTC
Updated:: Mar 05 2026 08:40:20 PM UTC
Start date:: 12/Nov/25

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