Fix flaky sessions_pool test by aligning MinPoolSize with MaxActiveSessions #31673

Copilot · 2026-01-03T20:40:26Z

Removed executor configurations and added auto config settings.

Changelog entry

The StressTestAsync/0 test was flaky because MinPoolSize defaulted to 10 while MaxActiveSessions was set to 1. Sessions removed for KeepAlive operations (triggered every 10ms by aggressive test thresholds) could be lost on failure, leaving the pool empty despite the sessionsCount > MinPoolSize deletion guard.

Changelog category

Not for changelog (changelog entry is not required)

Description for reviewers

...

Changes

Set MinPoolSize to match MaxActiveSessions in test setup:

auto clientSettings = TClientSettings().SessionPoolSettings(
    TSessionPoolSettings()
        .MaxActiveSessions(maxActiveSessions)
        .MinPoolSize(maxActiveSessions)  // Added
        .KeepAliveIdleThreshold(TDuration::MilliSeconds(10))
        .CloseIdleThreshold(TDuration::MilliSeconds(10)));

This prevents session deletion regardless of KeepAlive outcomes, making the test deterministic.

Changelog

Fix flaky YdbSdkSessionsPool.StressTestAsync/0 test by setting MinPoolSize equal to MaxActiveSessions, preventing race condition where sessions could be lost during KeepAlive operations.

Original prompt

This section details on the original issue you should resolve

<issue_title>flaky test: ydb/public/sdk/cpp/tests/integration/sessions_pool/YdbSdkSessionsPool.StressTestAsync/0</issue_title>
<issue_description>ydb/public/sdk/cpp/tests/integration/sessions_pool/main.cpp:308:
Expected equality of these values:
Client->GetCurrentPoolSize()
Which is: 0
activeSessionsLimit
Which is: 1</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes Test failure in ydb/public/sdk/cpp/tests/integration/sessions_pool/YdbSdkSessionsPool.StressTestAsync/0 #31672

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github-actions · 2026-01-03T20:43:20Z

Hi! Thank you for contributing!
The tests on this PR will run after a maintainer adds an ok-to-test label to this PR manually. Thank you for your patience!

ydbot · 2026-01-03T20:44:16Z

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github-actions · 2026-01-03T20:46:06Z

🟢 2026-01-03 21:16:27 UTC The validation of the Pull Request description is successful.

The test was flaky because MinPoolSize defaulted to 10 while MaxActiveSessions could be set to 1. When the periodic session cleanup task ran, it would check if sessionsCount > MinPoolSize before deleting idle sessions. With the default MinPoolSize of 10 and only 1 session, the condition (1 > 10) was false, so sessions should not be deleted. However, when sessions were removed from the pool for KeepAlive operations and the KeepAlive failed (due to network issues or timeouts during testing), the session could be lost, leading to an empty pool. By explicitly setting MinPoolSize to match MaxActiveSessions, we ensure that sessions are never deleted from the pool due to idle timeout, regardless of KeepAlive success or failure. This makes the test deterministic and prevents the flaky behavior where GetCurrentPoolSize() would sometimes return 0 instead of the expected activeSessionsLimit. Co-authored-by: asmyasnikov <[email protected]>

github-actions · 2026-01-03T21:10:39Z

⚪ 2026-01-03 21:10:38 UTC Pre-commit check linux-x86_64-release-asan for 75e00aa has started.
⚪ 2026-01-03 21:10:55 UTC Artifacts will be uploaded here
⚪ 2026-01-03 21:13:05 UTC ya make is running...
🟢 2026-01-03 21:18:26 UTC Tests successful.

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED^?
22	22	0	0	0	0

🟢 2026-01-03 21:18:32 UTC Build successful.
🟢 2026-01-03 21:18:51 UTC ydbd size 3.8 GiB changed* by +6.1 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: `b929c77`	merge: `75e00aa`	diff	diff %
ydbd size	4 104 377 800 Bytes	4 104 384 000 Bytes	+6.1 KiB	+0.000%
ydbd stripped size	1 535 378 448 Bytes	1 535 381 040 Bytes	+2.5 KiB	+0.000%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

github-actions · 2026-01-03T21:11:21Z

⚪ 2026-01-03 21:11:21 UTC Pre-commit check linux-x86_64-relwithdebinfo for 75e00aa has started.
⚪ 2026-01-03 21:11:37 UTC Artifacts will be uploaded here
⚪ 2026-01-03 21:13:43 UTC ya make is running...
🟢 2026-01-03 21:18:43 UTC Tests successful.

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED^?
22	22	0	0	0	0

🟢 2026-01-03 21:18:49 UTC Build successful.
🟢 2026-01-03 21:19:04 UTC ydbd size 2.3 GiB changed* by +2.4 KiB, which is < 100.0 KiB vs main: OK

ydbd size dash	main: `b929c77`	merge: `75e00aa`	diff	diff %
ydbd size	2 495 880 832 Bytes	2 495 883 312 Bytes	+2.4 KiB	+0.000%
ydbd stripped size	530 644 416 Bytes	530 644 992 Bytes	+576 Bytes	+0.000%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

Copilot

Pull request overview

This PR fixes a flaky test (YdbSdkSessionsPool.StressTestAsync/0) by aligning the MinPoolSize session pool setting with MaxActiveSessions to prevent sessions from being deleted during aggressive KeepAlive operations.

Key Changes

Set MinPoolSize equal to MaxActiveSessions in the test's SetUp() method to ensure session pool stability during stress testing

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github-actions · 2026-01-13T04:40:37Z

⚪ 2026-01-13 04:40:36 UTC Pre-commit check linux-x86_64-relwithdebinfo for b0f7a28 has started.
⚪ 2026-01-13 04:40:53 UTC Artifacts will be uploaded here
⚪ 2026-01-13 04:43:07 UTC ya make is running...
🟢 2026-01-13 04:48:14 UTC Tests successful.

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED^?
22	22	0	0	0	0

🟢 2026-01-13 04:48:22 UTC Build successful.
🟢 2026-01-13 04:48:37 UTC ydbd size 2.3 GiB changed* by 0 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: `afdd375`	merge: `b0f7a28`	diff	diff %
ydbd size	2 495 089 776 Bytes	2 495 089 776 Bytes	0 Bytes	0.000%
ydbd stripped size	530 796 928 Bytes	530 796 928 Bytes	0 Bytes	0.000%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

github-actions · 2026-01-13T04:40:38Z

⚪ 2026-01-13 04:40:38 UTC Pre-commit check linux-x86_64-release-asan for b0f7a28 has started.
⚪ 2026-01-13 04:40:54 UTC Artifacts will be uploaded here
⚪ 2026-01-13 04:43:01 UTC ya make is running...
🟢 2026-01-13 04:48:15 UTC Tests successful.

Ya make output | Test bloat

TESTS	PASSED	ERRORS	FAILED	SKIPPED	MUTED^?
22	22	0	0	0	0

🟢 2026-01-13 04:48:21 UTC Build successful.
🟢 2026-01-13 04:48:39 UTC ydbd size 3.8 GiB changed* by -96 Bytes, which is <= 0 Bytes vs main: OK

ydbd size dash	main: `afdd375`	merge: `b0f7a28`	diff	diff %
ydbd size	4 102 547 728 Bytes	4 102 547 632 Bytes	-96 Bytes	-0.000%
ydbd stripped size	1 535 806 384 Bytes	1 535 806 320 Bytes	-64 Bytes	-0.000%

^{*please be aware that the difference is based on comparing your commit and the last completed build from the post-commit, check comparation}

Initial plan

a6e22a6

Copilot AI assigned Copilot and asmyasnikov Jan 3, 2026

Copilot started work on behalf of asmyasnikov January 3, 2026 20:40 View session

github-actions bot added the external label Jan 3, 2026

Copilot AI changed the title ~~[WIP] Fix flaky test in sessions pool for active session limit~~ Fix flaky sessions_pool test by aligning MinPoolSize with MaxActiveSessions Jan 3, 2026

Copilot AI requested a review from asmyasnikov January 3, 2026 21:04

Copilot finished work on behalf of asmyasnikov January 3, 2026 21:04

asmyasnikov added the not-for-changelog label Jan 3, 2026

github-actions bot added not-for-changelog and removed not-for-changelog labels Jan 3, 2026

asmyasnikov added the ok-to-test Special label used to approve a PR for testing on our infrastructure label Jan 3, 2026

github-actions bot removed the ok-to-test Special label used to approve a PR for testing on our infrastructure label Jan 3, 2026

asmyasnikov approved these changes Jan 6, 2026

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asmyasnikov marked this pull request as ready for review January 9, 2026 12:53

asmyasnikov requested a review from a team as a code owner January 9, 2026 12:53

asmyasnikov requested review from Gazizonoki and Copilot January 9, 2026 12:53

Copilot started reviewing on behalf of asmyasnikov January 9, 2026 12:54 View session

Copilot AI reviewed Jan 9, 2026

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asmyasnikov added the ok-to-test Special label used to approve a PR for testing on our infrastructure label Jan 13, 2026

github-actions bot removed the ok-to-test Special label used to approve a PR for testing on our infrastructure label Jan 13, 2026

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Fix flaky sessions_pool test by aligning MinPoolSize with MaxActiveSessions #31673

Fix flaky sessions_pool test by aligning MinPoolSize with MaxActiveSessions #31673

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Fix flaky sessions_pool test by aligning MinPoolSize with MaxActiveSessions #31673

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