[DevyanshMalhotra]

Description

Fixes #8980.

Corrects start timestamps for metric instruments created after a reader has already performed a collection.

Previously, newly created instruments could use the reader's previous collection timestamp even when it was earlier than the instrument's creation time.

The fix uses Math.max to select the later of the reader's previous collection timestamp and the instrument creation time.

Changes

• Fix start timestamps for delta synchronous instruments.
• Fix start timestamps for delta asynchronous instruments.
• Fix initial aggregator handle timestamps for cumulative asynchronous instruments.
• Add regression tests for all three cases, covering both memory modes.
• Update existing tests to use chronologically consistent timestamps.

Validation

• Confirmed all six new regression test invocations fail before the fix.
• Confirmed the regression tests pass after the fix.
• ./gradlew :sdk:metrics:spotlessApply — passed.
• ./gradlew :sdk:metrics:check — passed.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: DevyanshMalhotra / name: Devyansh Malhotra (87d2f50)

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Waiting on reviewers · refreshed 2026-10-31 11:53 UTC

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.38%. Comparing base (dc3019e) to head (87d2f50).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8992      +/-   ##
============================================
+ Coverage     90.36%   90.38%   +0.01%     
  Complexity    10995    10995              
============================================
  Files          1020     1020              
  Lines         30096    30099       +3     
  Branches       3929     3929              
============================================
+ Hits          27197    27204       +7     
+ Misses         1942     1937       -5     
- Partials        957      958       +1     

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[DevyanshMalhotra]

Hi maintainers,

I checked the failing CI jobs. The macOS Java 8 and Java 11 builds are failing in SynchronousInstrumentStressTest.partialWriteStressTest due to 10-second timeouts.

The remaining platform builds passed, and ./gradlew :sdk:metrics:check passes locally.

These appear potentially environment-related. Could someone please rerun the two failed macOS jobs to confirm?

Thanks!