grpc: deprecate InitialWindowSize and introduce InitialStreamWindowSize #8789

eshitachandwani · 2025-12-24T08:36:26Z

This PR

Changes the behavior of WithInitialWindowSize and WithInitialConnWindowSize dialOptions to enable BDP unconditionally.
Changes the behavior of InitialWindowSize and InitialConnWindowSize server options to enable BDP unconditionally.
Mark WithInitialWindowSize dialOption as deprecated and introduce a new dialOption WithInitialStreamWindowSize which just returns WithInitialWindowSize`
Mark InitialWindowSize server option as deprecated and introduce a new server option InitialStreamWindowSize which just returns InitialWindowSize
Changes the test accordingly

RELEASE NOTES:

grpc:
- Update WithInitialWindowSize and WithInitialConnWindowSize dialOptions and InitialWindowSize and InitialConnWindowSize server options to enable BDP unconditionally.
- Introduce a new dialOption WithInitialStreamWindowSize and a new server option InitialStreamWindowSize to enable BDP unconditionally and deprecate WithInitialWindowSize and InitialWindowSize

codecov · 2025-12-24T08:39:50Z

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.29%. Comparing base (4046676) to head (e91fa27).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
server.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8789      +/-   ##
==========================================
- Coverage   83.42%   83.29%   -0.13%     
==========================================
  Files         418      418              
  Lines       32897    32897              
==========================================
- Hits        27443    27403      -40     
- Misses       4069     4086      +17     
- Partials     1385     1408      +23

Files with missing lines	Coverage Δ
dialoptions.go	`91.09% <100.00%> (+2.02%)`	⬆️
server.go	`83.02% <0.00%> (+0.39%)`	⬆️

... and 27 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

arjan-bal

If you're using changes from the previous unmerged PR #8665, please cherry-pick and squash the commits from the original author for proper attribution.

eshitachandwani · 2025-12-25T10:54:14Z

If you're using changes from the previous unmerged PR #8665, please cherry-pick and squash the commits from the original author for proper attribution.

Done.

mbissa · 2025-12-26T09:17:28Z

test/end2end_test.go

+		if te.clientStaticWindow {
+			opts = append(opts, grpc.WithStaticStreamWindowSize(te.clientInitialWindowSize))
+		} else {
+			opts = append(opts, grpc.WithInitialWindowSize(te.clientInitialWindowSize))


We should add tests with both WithInitialStreamWindowSize and WithInitialWindowSize options to ensure both code paths are verified if they diverge in future.

arjan-bal

Please make the release notes imperative sentences, e.g.: Update WithInitialWindowSize and WithInitialConnWindowSize to enable BDP unconditionally..

Please combine similar changes to a single release note. For example, all the changes to the existing options can be a single note and the introduction of the new options can be a separate note.

dialoptions.go

test/channelz_test.go

arjan-bal · 2025-12-29T06:33:14Z

test/end2end_test.go

 	unaryServerInt              grpc.UnaryServerInterceptor
 	streamServerInt             grpc.StreamServerInterceptor
 	serverInitialWindowSize     int32
+	serverStaticWindow          bool


Can this variable be given a more boolean like name like isServerWindowStatic or useStaticServerWindow?

isServerWindowStatic reads more like natural English and answers the question "Is the server window static?". isServerStaticWindow feels less natural. Please change.

test/stream_cleanup_test.go

arjan-bal · 2026-01-02T04:41:52Z

test/end2end_test.go

+	clientInitialWindowSize          int32
+	clientUseInitialStreamWindowSize bool
+	clientInitialConnWindowSize      int32
+	clientStaticWindow               bool


Similar to the server side boolean, please change re-name to isClientWindowStatic

arjan-bal · 2026-01-02T04:44:01Z

test/end2end_test.go

+	serverStaticWindow               bool
+	clientStaticWindow               bool


Please rename the variables to be similar to isClientWindowStatic and isServerWindowStatic.

arjan-bal · 2026-01-02T04:55:08Z

test/end2end_test.go

 	unaryServerInt              grpc.UnaryServerInterceptor
 	streamServerInt             grpc.StreamServerInterceptor
 	serverInitialWindowSize     int32
+	serverStaticWindow          bool


isServerWindowStatic reads more like natural English and answers the question "Is the server window static?". isServerStaticWindow feels less natural. Please change.

arjan-bal · 2026-01-02T05:00:01Z

test/end2end_test.go

+		clientUseInitialStreamWindowSize: true,
+	}
+	for _, e := range listTestEnv() {
+		testConfigurableWindowSize(t, e, wc)


Does this test explicitly assert the static/dynamic behavior of the client/server windows? I would expect the test to break if the window type changes unexpectedly. Is that currently covered?

add option , deprecate old

c6abd37

eshitachandwani added this to the 1.79 Release milestone Dec 24, 2025

eshitachandwani added Type: Bug Type: Feature New features or improvements in behavior and removed Type: Bug labels Dec 24, 2025

eshitachandwani requested review from arjan-bal and mbissa December 24, 2025 09:31

eshitachandwani assigned arjan-bal and mbissa Dec 24, 2025

arjan-bal reviewed Dec 24, 2025

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arjan-bal assigned eshitachandwani and unassigned arjan-bal Dec 24, 2025

Pramodh-G and others added 3 commits December 25, 2025 16:14

from the closed PR

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remove duplicate

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remove variable

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eshitachandwani requested a review from arjan-bal December 25, 2025 10:55

eshitachandwani assigned arjan-bal and unassigned eshitachandwani Dec 25, 2025

mbissa reviewed Dec 26, 2025

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mbissa removed their assignment Dec 26, 2025

initial stream window size dial option test

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arjan-bal reviewed Dec 29, 2025

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arjan-bal assigned eshitachandwani and unassigned arjan-bal Dec 29, 2025

eshitachandwani added 2 commits December 29, 2025 16:51

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eshitachandwani requested review from arjan-bal and mbissa December 29, 2025 14:16

eshitachandwani assigned arjan-bal and mbissa and unassigned eshitachandwani Dec 29, 2025

arjan-bal reviewed Jan 2, 2026

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arjan-bal assigned eshitachandwani and unassigned arjan-bal Jan 2, 2026

mbissa removed their assignment Jan 8, 2026

grpc: deprecate InitialWindowSize and introduce InitialStreamWindowSize #8789

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grpc: deprecate InitialWindowSize and introduce InitialStreamWindowSize #8789

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eshitachandwani commented Dec 24, 2025 •

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