Remove HAVE_CLOCK_MONOTONIC and dead fallback code #124120

Copilot · 2026-02-07T01:43:06Z

Description

HAVE_CLOCK_MONOTONIC is always defined as 1 on all Unix-like platforms, so we can remove the macro and all associated fallback code.

Changes Made

Configuration Files

Removed HAVE_CLOCK_MONOTONIC check from src/coreclr/pal/src/configure.cmake
Removed HAVE_CLOCK_MONOTONIC from src/coreclr/pal/src/config.h.in
Removed HAVE_CLOCK_MONOTONIC check from src/mono/cmake/configure.cmake
Removed HAVE_CLOCK_MONOTONIC from src/mono/cmake/config.h.in
Removed HAVE_CLOCK_MONOTONIC check from src/native/libs/configure.cmake
Removed HAVE_CLOCK_MONOTONIC from src/native/libs/Common/pal_config.h.in
Removed HAVE_CLOCK_MONOTONIC check from src/native/minipal/configure.cmake
Removed HAVE_CLOCK_MONOTONIC from src/native/minipal/minipalconfig.h.in
Removed HAVE_CLOCK_MONOTONIC settings from eng/native/tryrun.cmake
Removed HAVE_CLOCK_MONOTONIC settings from eng/native/tryrun_ios_tvos.cmake
Removed HAVE_CLOCK_MONOTONIC settings from eng/native/tryrun.browser.cmake

Source Files

src/native/minipal/time.c: Changed #elif HAVE_CLOCK_MONOTONIC to #else, removed error fallback, simplified assert statements to more concise form
src/native/libs/System.Native/pal_threading.c and pal_crossprocessmutex.c: Simplified to #if HAVE_PTHREAD_CONDATTR_SETCLOCK (removed && HAVE_CLOCK_MONOTONIC)
src/coreclr/pal/src/synchmgr/synchmanager.cpp: Removed fPreferMonotonicClock parameter from GetAbsoluteTimeout() (was always TRUE)
src/mono/mono/utils/mono-time.c: Changed #ifdef HAVE_CLOCK_MONOTONIC to #ifdef CLOCK_MONOTONIC to guard against Windows WASM builds where the POSIX constant is unavailable
src/mono/mono/eventpipe/ep-rt-mono.c: Removed Apple platform #undef HAVE_CLOCK_MONOTONIC workaround and gettimeofday() fallback

All code now assumes clock_gettime(CLOCK_MONOTONIC, ...) is available on Unix-like platforms where the CLOCK_MONOTONIC constant is defined.

Testing

✅ CoreCLR + Libraries build successful
✅ Mono build successful
✅ All builds passing after addressing review feedback
✅ No build errors detected
✅ CI failures analyzed: All test failures are tracked known issues unrelated to this PR (#124052, #110173)

Net -81 lines across 17 files.

Original prompt

Create PR to delete HAVE_CLOCK_MONOTONIC, inclduing the config that sets it up. It is defined as 1 on all Unix-like platforms supported by this repo. Also make sure that all dead fallback paths for !HAVE_CLOCK_MONOTONIC

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

src/coreclr/pal/src/synchmgr/synchmanager.cpp

jkotas · 2026-02-07T02:12:54Z

@copilot Please fix this build break on Windows

D:\a\_work\1\s\src\mono\mono\utils\mono-time.c(193): error C2065: 'CLOCK_MONOTONIC': undeclared identifier
  D:\a\_work\1\s\src\mono\mono\utils\mono-time.c(193): warning C4047: '=': 'mono_clock_id_t' differs in levels of indirection from 'int'

The parameter was always TRUE, so simplify by removing it and always preferring CLOCK_MONOTONIC when available. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

CLOCK_MONOTONIC is a POSIX constant not available on Windows. Guard the assignment with #ifdef to prevent build failures on Windows/WASM builds. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

Copilot · 2026-02-07T02:36:03Z

@copilot Please fix this build break on Windows

D:\a\_work\1\s\src\mono\mono\utils\mono-time.c(193): error C2065: 'CLOCK_MONOTONIC': undeclared identifier

...

Fixed. Added #ifdef CLOCK_MONOTONIC guard since the constant is not available on Windows. The TARGET_WASM build configuration compiles the Linux/WASM code section on Windows, but CLOCK_MONOTONIC is a POSIX constant that doesn't exist on Windows. (cbeadd8)

src/mono/mono/utils/mono-time.c

Deleted all instances of mono_clock_init() and inlined the initialization. On Darwin, the host_get_clock_service call is now directly in mini-posix.c. On Linux/non-Darwin, sampling_clock is already set to CLOCK_MONOTONIC directly. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

jkotas · 2026-02-07T03:06:10Z

@copilot Revert last commit, it does not look like an improvement

This reverts commit 3ca9315. Keeping the mono_clock_init() wrapper function as requested. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

Copilot · 2026-02-07T03:13:46Z

@copilot Revert last commit, it does not look like an improvement

Reverted. The mono_clock_init() wrapper function has been restored. (3e2ab4d)

src/mono/mono/eventpipe/ep-rt-mono.c

src/native/minipal/time.c

Co-authored-by: Aaron R Robinson <arobins@microsoft.com>

stephentoub · 2026-02-07T15:27:27Z

@copilot analyze the build and test failures in CI

Changed assert statements to use the simpler form: assert(result == 0 && "message") instead of if (result != 0) { assert(!"message"); } Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Copilot · 2026-02-07T15:49:24Z

@copilot analyze the build and test failures in CI

I analyzed the PR and couldn't find completed Azure DevOps CI builds yet. The local builds (CoreCLR + Libraries, Mono) all succeed with the current changes. The PR removes the HAVE_CLOCK_MONOTONIC macro and simplifies code to assume CLOCK_MONOTONIC is available on all Unix platforms. If specific CI failures appear, please share the build URLs or failure details and I can investigate further.

src/native/minipal/time.c

jkotas · 2026-02-07T20:40:22Z

@copilot analyze the build and test failures in CI

Copilot · 2026-02-07T20:44:55Z

@copilot analyze the build and test failures in CI

No completed CI builds found for this PR yet. The GitHub status API shows "pending" with 0 status checks. The azdo-helix-failures skill couldn't locate any Azure DevOps builds. Local builds (CoreCLR + Libraries, Mono) all pass successfully. Once CI completes, I can analyze any failures if they occur.

stephentoub · 2026-02-08T00:02:47Z

@copilot analyze the build and test failures in CI

Copilot · 2026-02-08T00:08:53Z

@copilot analyze the build and test failures in CI

CI Analysis Summary

Build: 1284159 | Status: Failed | Tests: 26 failed / 3,679,973 passed (99.99% pass rate)

Failures Found (All Known Issues - Not PR-Related)

1. crossgen2determinism test failure (linux-arm)

Issue: #124052 - "Crossgen2 coreroot_determinism test failure (exit code 134)"
Labels: Known Build Error, blocking-clean-ci
Hit count: 6 in 24 hours, 16 in 7 days
Cause: Crossgen2 crash (SIGABRT) during determinism validation on linux-arm32
PR-related: ❌ No (affects multiple unrelated PRs)

2. stackoverflowtester test failure (linux-x64)

Issue: #110173 - "Test failure: baseservices/exceptions/stackoverflow/stackoverflowtester/stackoverflowtester.cmd"
Labels: Known Build Error
PR-related: ❌ No (long-standing known issue)

Build Analysis Result

✅ Build Analysis correctly identified both failures as known issues.

Recommendation

SAFE TO MERGE - All failures are tracked known issues unrelated to the HAVE_CLOCK_MONOTONIC removal. Local builds pass successfully. The changes don't touch Crossgen2, ReadyToRun, or stack overflow handling code.

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Copilot AI assigned Copilot and jkotas Feb 7, 2026

Copilot started work on behalf of jkotas February 7, 2026 01:43 View session

github-actions bot added the needs-area-label An area label is needed to ensure this gets routed to the appropriate area owners label Feb 7, 2026

Remove HAVE_CLOCK_MONOTONIC and dead fallback code

649ce23

Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

jkotas mentioned this pull request Feb 7, 2026

Fix #123950: Add missing HAVE_CLOCK_MONOTONIC to config.h.in #124086

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Copilot AI changed the title ~~[WIP] Remove HAVE_CLOCK_MONOTONIC configuration and fallback paths~~ Remove HAVE_CLOCK_MONOTONIC and dead fallback code Feb 7, 2026

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Remove fPreferMonotonicClock parameter from GetAbsoluteTimeout

78a34a7

The parameter was always TRUE, so simplify by removing it and always preferring CLOCK_MONOTONIC when available. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

Copilot finished work on behalf of jkotas February 7, 2026 02:26

Copilot started work on behalf of jkotas February 7, 2026 02:26 View session

Fix Windows build: guard CLOCK_MONOTONIC with ifdef

cbeadd8

CLOCK_MONOTONIC is a POSIX constant not available on Windows. Guard the assignment with #ifdef to prevent build failures on Windows/WASM builds. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

Copilot finished work on behalf of jkotas February 7, 2026 02:38

github-actions bot added area-PAL-coreclr and removed needs-area-label An area label is needed to ensure this gets routed to the appropriate area owners labels Feb 7, 2026

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Revert "Remove mono_clock_init and use CLOCK_MONOTONIC directly"

3e2ab4d

This reverts commit 3ca9315. Keeping the mono_clock_init() wrapper function as requested. Co-authored-by: jkotas <6668460+jkotas@users.noreply.github.com>

AaronRobinsonMSFT approved these changes Feb 7, 2026

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Test failure: baseservices/exceptions/stackoverflow/stackoverflowtester/stackoverflowtester.cmd #110173

Open

Test Failure: readytorun/GenericCycleDetection/Depth1Test/Depth1Test.cmd #123982

Open

Update src/mono/mono/eventpipe/ep-rt-mono.c

39af12f

Co-authored-by: Aaron R Robinson <arobins@microsoft.com>

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The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

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[android-arm64] The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#6408

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Copilot started work on behalf of stephentoub February 7, 2026 15:27 View session

Simplify assert statements in minipal time.c

b800389

Changed assert statements to use the simpler form: assert(result == 0 && "message") instead of if (result != 0) { assert(!"message"); } Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Copilot AI requested a review from stephentoub February 7, 2026 15:50

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Merge branch 'main' into copilot/remove-have-clock-monotonic

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crossgen2 failing on Linux Arm32 intermittently #124007

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Crossgen2 coreroot_determinism test failure (exit code 134) #124052

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jkotas merged commit 737dcdd into main Feb 8, 2026
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jkotas deleted the copilot/remove-have-clock-monotonic branch February 8, 2026 09:06

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[main] Source code updates from dotnet/runtime dotnet/dotnet#4727

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Remove HAVE_CLOCK_MONOTONIC and dead fallback code #124120

Remove HAVE_CLOCK_MONOTONIC and dead fallback code #124120

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Description

Changes Made

Configuration Files

Source Files

Testing

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CI Analysis Summary

Failures Found (All Known Issues - Not PR-Related)

Build Analysis Result

Recommendation

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