test(pyamber): add unit tests for TimedBuffer

[Ma77Ball]

What changes were proposed in this PR?

• Add amber/src/test/python/core/util/buffer/test_timed_buffer.py, a new pytest spec for TimedBuffer, which previously had no dedicated unit tests.
• Cover put buffering and ordering, and flush-on-demand (emit and clear, empty-buffer, and generator laziness).
• Cover flush-on-size at, below, and above max_message_num.
• Cover flush-on-time using a monkeypatched module clock (elapsed-interval flush, timer reset after flush, sub-threshold no-flush) with no real sleeps.

Any related issues, documentation, discussions?

Closes: #6636

How was this PR tested?

• Run: cd amber && python -m pytest src/test/python/core/util/buffer/test_timed_buffer.py, expect all 13 tests passing.
• Test-only change; no production code is modified.

Was this PR authored or co-authored using generative AI tooling?

Co-authored with Claude Opus 4.8 in compliance with ASF

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• No candidates found from git blame history.

[github-actions]

⚠️ Benchmark changes need a look

🟢 2 better · 🔴 3 worse · ⚪ 10 noise (<±5%) · 0 without baseline

Compared against main f14cd39 benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	411	0.251	24,713/30,653/30,653 us	🔴 +30.9% / 🔴 +96.1%
⚪	bs=100 sw=10 sl=64	930	0.568	105,798/129,048/129,048 us	⚪ within ±5% / 🔴 +21.7%
🟢	bs=1000 sw=10 sl=64	1,076	0.657	932,901/982,236/982,236 us	🟢 -16.1% / 🟢 -6.3%

Baseline details

Latest main f14cd39 from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	411 tuples/sec	467 tuples/sec	767.23 tuples/sec	-12.0%	-46.4%
bs=10 sw=10 sl=64	MB/s	0.251 MB/s	0.285 MB/s	0.468 MB/s	-11.9%	-46.4%
bs=10 sw=10 sl=64	p50	24,713 us	18,882 us	12,705 us	+30.9%	+94.5%
bs=10 sw=10 sl=64	p95	30,653 us	31,420 us	15,633 us	-2.4%	+96.1%
bs=10 sw=10 sl=64	p99	30,653 us	31,420 us	20,214 us	-2.4%	+51.6%
bs=100 sw=10 sl=64	throughput	930 tuples/sec	962 tuples/sec	1,001 tuples/sec	-3.3%	-7.1%
bs=100 sw=10 sl=64	MB/s	0.568 MB/s	0.587 MB/s	0.611 MB/s	-3.2%	-7.1%
bs=100 sw=10 sl=64	p50	105,798 us	101,950 us	99,949 us	+3.8%	+5.9%
bs=100 sw=10 sl=64	p95	129,048 us	129,222 us	105,996 us	-0.1%	+21.7%
bs=100 sw=10 sl=64	p99	129,048 us	129,222 us	117,999 us	-0.1%	+9.4%
bs=1000 sw=10 sl=64	throughput	1,076 tuples/sec	1,062 tuples/sec	1,033 tuples/sec	+1.3%	+4.1%
bs=1000 sw=10 sl=64	MB/s	0.657 MB/s	0.648 MB/s	0.631 MB/s	+1.4%	+4.2%
bs=1000 sw=10 sl=64	p50	932,901 us	915,593 us	974,571 us	+1.9%	-4.3%
bs=1000 sw=10 sl=64	p95	982,236 us	1,171,368 us	1,016,467 us	-16.1%	-3.4%
bs=1000 sw=10 sl=64	p99	982,236 us	1,171,368 us	1,048,798 us	-16.1%	-6.3%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,486.46,200,128000,411,0.251,24713.09,30653.24,30653.24
1,100,10,64,20,2149.62,2000,1280000,930,0.568,105798.34,129048.05,129048.05
2,1000,10,64,20,18588.86,20000,12800000,1076,0.657,932901.05,982236.34,982236.34

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.51%. Comparing base (f14cd39) to head (59504e9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #6637   +/-   ##
=========================================
  Coverage     74.51%   74.51%           
  Complexity     3440     3440           
=========================================
  Files          1157     1157           
  Lines         45621    45621           
  Branches       5031     5031           
=========================================
  Hits          33996    33996           
  Misses         9973     9973           
  Partials       1652     1652           

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)		Carriedforward from 226337d
agent-service	76.76% <ø> (ø)		Carriedforward from 226337d
amber	66.82% <ø> (ø)		Carriedforward from 226337d
computing-unit-managing-service	18.00% <ø> (ø)		Carriedforward from 226337d
config-service	66.66% <ø> (ø)		Carriedforward from 226337d
file-service	66.80% <ø> (ø)		Carriedforward from 226337d
frontend	78.29% <ø> (ø)		Carriedforward from 226337d
notebook-migration-service	78.94% <ø> (ø)		Carriedforward from 226337d
pyamber	91.83% <ø> (ø)
workflow-compiling-service	55.14% <ø> (ø)		Carriedforward from 226337d

*This pull request uses carry forward flags. Click here to find out more.

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[aglinxinyuan]

LGTM!

[Copilot]

Pull request overview

This PR adds dedicated pytest unit coverage for the Python worker TimedBuffer utility in Amber, aligning with issue #6636’s goal of deterministic, mocked-time tests for size- and time-based flushing.

Changes:

• Add a new test_timed_buffer.py spec covering buffering semantics, flush-on-demand, flush-on-size, and flush-on-time with a monkeypatched clock.
• Validate ordering guarantees and generator laziness (side effects occur on iteration, not generator creation).
• Assert default configuration values for TimedBuffer.

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