feat: emit TaskBlock events for JVM blocking states by kaahos · Pull Request #665 · DataDog/java-profiler

kaahos · 2026-07-16T13:52:29Z

What does this PR do?:

Adds JVM TaskBlock producers for LockSupport.park and monitor contention/wait states, wiring JVM state transitions into the synchronous TaskBlock recording API.

Motivation:

Common JVM blocking operations can be represented as TaskBlock events instead of relying on wall-clock signals against blocked threads.

Additional Notes:

Virtual threads are not explicitly emitted by this PR. This change focuses on platform-thread JVM blocking states exposed through the existing VM entry paths.

How to test the change?:

Automated coverage includes native park-state tests and Java integration tests for park, monitor wait, monitor contention, JVMTI-backed variants, and combined wall-clock mitigation behavior.

./.claude/commands/build-and-summarize testDebug

For Datadog employees:

If this PR touches code that signs or publishes builds or packages, or handles credentials of any kind, I've requested a security review (run the dd:platform-security-review skill, or file a request via the PSEC review form).
bewaire also runs automatically on every PR.
This PR doesn't touch any of that.
JIRA: [JIRA-XXXX]

dd-octo-sts · 2026-07-16T14:10:14Z

CI Test Results

Run: #29571012127 | Commit: 4d61bb0 | Duration: 16m 43s (longest job)

✅ All 32 test jobs passed

Status Overview

JDK	glibc-aarch64/debug	glibc-amd64/debug	musl-aarch64/debug	musl-amd64/debug
8	-	✅	-	-
8-ibm	-	✅	-	-
8-j9	✅	✅	-	-
8-librca	-	-	✅	✅
8-orcl	-	✅	-	-
11	-	✅	-	-
11-j9	✅	✅	-	-
11-librca	-	-	✅	✅
17	✅	✅	-	-
17-graal	✅	✅	-	-
17-j9	✅	✅	-	-
17-librca	-	-	✅	✅
21	✅	✅	-	-
21-graal	✅	✅	-	-
21-librca	-	-	✅	✅
25	✅	✅	-	-
25-graal	✅	✅	-	-
25-librca	-	-	✅	✅

Legend: ✅ passed | ❌ failed | ⚪ skipped | 🚫 cancelled

Summary: Total: 32 | Passed: 32 | Failed: 0

Updated: 2026-07-17 10:05:16 UTC

dd-octo-sts · 2026-07-16T15:51:05Z

Benchmark Results (commit `38efbf8`)

Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125051342 Commit: 38efbf8f7d94004f2ec282bc6c50148a99f67616

⚠️ Significant outliers

🔴 fj-kmeans (JDK 21): runtime +4.1% (2719→2830 ms)
🔴 fj-kmeans (JDK 25): runtime +2.8% (2737→2815 ms)

Runtime details (per benchmark × JDK)

Benchmark	JDK	Latest	Dev	Δ (dev vs latest)	Issues L/D
akka-uct	21	✅ 10365 ms (21 iters)	✅ 10195 ms (21 iters)	≈ -1.6% (±11.4%)	— / —
akka-uct	25	✅ 8859 ms (24 iters)	✅ 8925 ms (24 iters)	≈ +0.7% (±10.1%)	— / —
finagle-chirper	21	✅ 5945 ms (33 iters)	✅ 5953 ms (33 iters)	≈ +0.1% (±24.9%)	⚠️ W:3 / ⚠️ W:3
finagle-chirper	25	✅ 5495 ms (36 iters)	✅ 5431 ms (36 iters)	≈ -1.2% (±24.2%)	⚠️ W:3 / ⚠️ W:3
fj-kmeans	21	✅ 2719 ms (68 iters)	✅ 2830 ms (66 iters)	🔴 +4.1%	— / —
fj-kmeans	25	✅ 2737 ms (68 iters)	✅ 2815 ms (66 iters)	🔴 +2.8%	— / —
future-genetic	21	✅ 2114 ms (88 iters)	✅ 2140 ms (87 iters)	≈ +1.2% (±2.7%)	— / —
future-genetic	25	✅ 2080 ms (90 iters)	✅ 2126 ms (88 iters)	≈ +2.2% (±2.5%)	— / —
naive-bayes	21	✅ 1299 ms (131 iters)	✅ 1232 ms (139 iters)	≈ -5.2% (±31.9%)	— / —
naive-bayes	25	✅ 997 ms (172 iters)	✅ 1004 ms (170 iters)	≈ +0.7% (±31.8%)	— / —
reactors	21	✅ 16202 ms (15 iters)	✅ 15908 ms (15 iters)	≈ -1.8% (±7.6%)	— / —
reactors	25	✅ 18524 ms (15 iters)	✅ 18484 ms (15 iters)	≈ -0.2% (±3.9%)	— / —

Internal counter details (ddprof)

ddprof internal counters, latest / dev (✅ = 0, · = unavailable):

Benchmark	JDK	Dropped rec	Dropped jvmti	Dropped trace	Skipped WC	AGCT fail	Unwind fail
akka-uct	21	✅ / ✅	✅ / ✅	2 / ✅	2045 / 1958	✅ / ✅	✅ / ✅
akka-uct	25	✅ / ✅	✅ / ✅	✅ / 3	2353 / 2059	✅ / ✅	✅ / ✅
finagle-chirper	21	✅ / ✅	✅ / ✅	6 / 2	8437 / 8382	✅ / ✅	✅ / ✅
finagle-chirper	25	✅ / ✅	✅ / ✅	✅ / 2	8800 / 8439	✅ / ✅	✅ / ✅
fj-kmeans	21	✅ / ✅	✅ / ✅	2 / 2	1248 / 1279	✅ / ✅	✅ / ✅
fj-kmeans	25	✅ / ✅	✅ / ✅	4 / 1	1262 / 1271	✅ / ✅	✅ / ✅
future-genetic	21	✅ / ✅	✅ / ✅	✅ / ✅	2963 / 2980	✅ / ✅	✅ / ✅
future-genetic	25	✅ / ✅	✅ / ✅	2 / 3	2955 / 2936	✅ / ✅	✅ / ✅
naive-bayes	21	✅ / ✅	✅ / ✅	3 / 7	3466 / 3539	✅ / ✅	✅ / ✅
naive-bayes	25	✅ / ✅	✅ / ✅	5 / 1	3478 / 3531	✅ / ✅	✅ / ✅
reactors	21	✅ / ✅	✅ / ✅	✅ / ✅	1700 / 1609	✅ / ✅	✅ / ✅
reactors	25	✅ / ✅	✅ / ✅	✅ / ✅	1905 / 1873	✅ / ✅	✅ / ✅

dd-octo-sts · 2026-07-16T15:53:41Z

Reliability & Chaos Results

✅ All reliability & chaos checks passed Pipeline: https://gitlab.ddbuild.io/DataDog/java-profiler/-/pipelines/125035442

dd-octo-sts · 2026-07-16T22:45:20Z

Benchmark Results (commit `cdb8274`)

Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125162043 Commit: cdb8274124fc1947560c5c91bbf213a248e6b608

⚠️ Significant outliers

🔴 fj-kmeans (JDK 21): runtime +5.1% (2683→2821 ms)

Runtime details (per benchmark × JDK)

Benchmark	JDK	Latest	Dev	Δ (dev vs latest)	Issues L/D
finagle-chirper	21	✅ 5956 ms (33 iters)	✅ 6031 ms (33 iters)	≈ +1.3% (±24.8%)	⚠️ W:3 / ⚠️ W:3
finagle-chirper	25	✅ 5457 ms (36 iters)	✅ 5444 ms (36 iters)	≈ -0.2% (±23.9%)	⚠️ W:3 / ⚠️ W:3
fj-kmeans	21	✅ 2683 ms (70 iters)	✅ 2821 ms (66 iters)	🔴 +5.1%	— / —
fj-kmeans	25	✅ 2786 ms (67 iters)	✅ 2839 ms (66 iters)	≈ +1.9% (±2.7%)	— / —
future-genetic	21	✅ 2063 ms (90 iters)	✅ 2095 ms (89 iters)	≈ +1.6% (±2.6%)	— / —
future-genetic	25	✅ 2072 ms (90 iters)	✅ 2125 ms (87 iters)	≈ +2.6% (±2.6%)	— / —
naive-bayes	21	✅ 1257 ms (135 iters)	✅ 1250 ms (136 iters)	≈ -0.6% (±32.8%)	— / —
reactors	21	✅ 16137 ms (15 iters)	✅ 15974 ms (15 iters)	≈ -1% (±7.5%)	— / —
reactors	25	✅ 18395 ms (15 iters)	✅ 18505 ms (15 iters)	≈ +0.6% (±4.4%)	— / —

Internal counter details (ddprof)

ddprof internal counters, latest / dev (✅ = 0, · = unavailable):

Benchmark	JDK	Dropped rec	Dropped jvmti	Dropped trace	Skipped WC	AGCT fail	Unwind fail
akka-uct	21	✅ / ✅	✅ / ✅	✅ / ✅	✅ / ✅	✅ / ✅	✅ / ✅
akka-uct	25	✅ / ✅	✅ / ✅	1 / 1	2260 / 2182	✅ / ✅	✅ / ✅
finagle-chirper	21	✅ / ✅	✅ / ✅	4 / 3	8741 / 8673	✅ / ✅	✅ / ✅
finagle-chirper	25	✅ / ✅	✅ / ✅	1 / ✅	8238 / 8373	✅ / ✅	✅ / ✅
fj-kmeans	21	✅ / ✅	✅ / ✅	4 / 2	1241 / 1256	✅ / ✅	✅ / ✅
fj-kmeans	25	✅ / ✅	✅ / ✅	2 / ✅	1287 / 1282	✅ / ✅	✅ / ✅
future-genetic	21	✅ / ✅	✅ / ✅	2 / 1	2971 / 2981	✅ / ✅	✅ / ✅
future-genetic	25	✅ / ✅	✅ / ✅	1 / 1	2968 / 2956	✅ / ✅	✅ / ✅
naive-bayes	21	✅ / ✅	✅ / ✅	5 / 3	3468 / 3474	✅ / ✅	✅ / ✅
naive-bayes	25	✅ / ✅	✅ / ✅	9 / 3	3464 / 3465	✅ / ✅	✅ / ✅
reactors	21	✅ / ✅	✅ / ✅	1 / 2	1531 / 1536	✅ / ✅	✅ / ✅
reactors	25	✅ / ✅	✅ / ✅	1 / ✅	1857 / 1856	✅ / ✅	✅ / ✅

dd-octo-sts · 2026-07-17T08:24:56Z

Benchmark Results (commit `e13ec27`)

Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125211559 Commit: e13ec275311412f74c94ccb558f2c544418a0634

✅ Within expected boundaries

No significant runtime deltas (all within run-to-run noise) and no internal-counter outliers.

Runtime details (per benchmark × JDK)

Benchmark	JDK	Latest	Dev	Δ (dev vs latest)	Issues L/D
akka-uct	21	✅ 10495 ms (21 iters)	✅ 10316 ms (21 iters)	≈ -1.7% (±10.8%)	— / —
akka-uct	25	✅ 8849 ms (24 iters)	✅ 8938 ms (24 iters)	≈ +1% (±10.2%)	— / —
finagle-chirper	21	✅ 5936 ms (33 iters)	✅ 5938 ms (33 iters)	≈ +0% (±24.9%)	⚠️ W:3 / ⚠️ W:3
finagle-chirper	25	✅ 5534 ms (36 iters)	✅ 5474 ms (36 iters)	≈ -1.1% (±24.5%)	⚠️ W:3 / ⚠️ W:4
fj-kmeans	21	✅ 2773 ms (67 iters)	✅ 2775 ms (67 iters)	≈ +0.1% (±2.7%)	— / —
fj-kmeans	25	✅ 2803 ms (66 iters)	✅ 2840 ms (66 iters)	≈ +1.3% (±2.6%)	— / —
future-genetic	21	✅ 2090 ms (89 iters)	✅ 2093 ms (89 iters)	≈ +0.1% (±2.7%)	— / —
future-genetic	25	✅ 2086 ms (89 iters)	✅ 2118 ms (87 iters)	≈ +1.5% (±2.4%)	— / —
naive-bayes	21	✅ 1251 ms (136 iters)	✅ 1268 ms (135 iters)	≈ +1.4% (±33.1%)	— / —
naive-bayes	25	✅ 1016 ms (169 iters)	✅ 1028 ms (166 iters)	≈ +1.2% (±31.8%)	— / —
reactors	25	✅ 18334 ms (15 iters)	✅ 18614 ms (15 iters)	≈ +1.5% (±4.6%)	— / —

Internal counter details (ddprof)

ddprof internal counters, latest / dev (✅ = 0, · = unavailable):

Benchmark	JDK	Dropped rec	Dropped jvmti	Dropped trace	Skipped WC	AGCT fail	Unwind fail
akka-uct	21	✅ / ✅	✅ / ✅	2 / 1	1924 / 1980	✅ / ✅	✅ / ✅
akka-uct	25	✅ / ✅	✅ / ✅	4 / 2	2127 / 2360	✅ / ✅	✅ / ✅
finagle-chirper	21	✅ / ✅	✅ / ✅	4 / 3	8378 / 8654	✅ / ✅	✅ / ✅
finagle-chirper	25	✅ / ✅	✅ / ✅	1 / ✅	8670 / 8433	✅ / ✅	✅ / ✅
fj-kmeans	21	✅ / ✅	✅ / ✅	✅ / ✅	1259 / 1251	✅ / ✅	✅ / ✅
fj-kmeans	25	✅ / ✅	✅ / ✅	1 / 4	1288 / 1264	✅ / ✅	✅ / ✅
future-genetic	21	✅ / ✅	✅ / ✅	1 / 4	2942 / 2917	✅ / ✅	✅ / ✅
future-genetic	25	✅ / ✅	✅ / ✅	1 / 1	2898 / 2871	✅ / ✅	✅ / ✅
naive-bayes	21	✅ / ✅	✅ / ✅	4 / 1	3492 / 3510	✅ / ✅	✅ / ✅
naive-bayes	25	✅ / ✅	✅ / ✅	1 / 3	3496 / 3479	✅ / ✅	✅ / ✅
reactors	21	✅ / ✅	✅ / ✅	✅ / 2	1858 / 1656	✅ / ✅	✅ / ✅
reactors	25	✅ / ✅	✅ / ✅	1 / ✅	1890 / 1893	✅ / ✅	✅ / ✅

dd-octo-sts · 2026-07-17T10:16:30Z

Benchmark Results (commit `c111812`)

Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125236325 Commit: c11181224884586f33d98ba19aa41e6162ecf5f2

✅ Within expected boundaries

No significant runtime deltas (all within run-to-run noise) and no internal-counter outliers.

Runtime details (per benchmark × JDK)

Benchmark	JDK	Latest	Dev	Δ (dev vs latest)	Issues L/D
akka-uct	21	✅ 10288 ms (21 iters)	✅ 10150 ms (21 iters)	≈ -1.3% (±11.5%)	— / —
akka-uct	25	✅ 8875 ms (24 iters)	✅ 8975 ms (24 iters)	≈ +1.1% (±10.6%)	— / —
finagle-chirper	25	✅ 5508 ms (36 iters)	✅ 5491 ms (36 iters)	≈ -0.3% (±24.3%)	⚠️ W:3 / ⚠️ W:3
fj-kmeans	21	✅ 2661 ms (69 iters)	✅ 2713 ms (69 iters)	≈ +2% (±2.7%)	— / —
fj-kmeans	25	✅ 2865 ms (66 iters)	✅ 2841 ms (66 iters)	≈ -0.8% (±2.6%)	— / —
future-genetic	21	✅ 2107 ms (88 iters)	✅ 2126 ms (87 iters)	≈ +0.9% (±2.7%)	— / —
future-genetic	25	✅ 2068 ms (89 iters)	✅ 2110 ms (88 iters)	≈ +2% (±2.6%)	— / —
naive-bayes	21	✅ 1292 ms (132 iters)	✅ 1224 ms (139 iters)	≈ -5.3% (±31.9%)	— / —
naive-bayes	25	✅ 1012 ms (169 iters)	✅ 984 ms (173 iters)	≈ -2.8% (±31.3%)	— / —
reactors	21	✅ 16274 ms (15 iters)	✅ 17426 ms (15 iters)	≈ +7.1% (±7.6%)	— / —
reactors	25	✅ 18845 ms (15 iters)	✅ 18270 ms (15 iters)	≈ -3.1% (±3.8%)	— / —

Internal counter details (ddprof)

ddprof internal counters, latest / dev (✅ = 0, · = unavailable):

Benchmark	JDK	Dropped rec	Dropped jvmti	Dropped trace	Skipped WC	AGCT fail	Unwind fail
akka-uct	21	✅ / ✅	✅ / ✅	3 / 4	2097 / 1909	✅ / ✅	✅ / ✅
akka-uct	25	✅ / ✅	✅ / ✅	3 / 1	2062 / 2338	✅ / ✅	✅ / ✅
finagle-chirper	21	✅ / ✅	✅ / ✅	1 / 2	8704 / 8842	✅ / ✅	✅ / ✅
finagle-chirper	25	✅ / ✅	✅ / ✅	3 / 2	8473 / 8584	✅ / ✅	✅ / ✅
fj-kmeans	21	✅ / ✅	✅ / ✅	1 / 1	1246 / 1251	✅ / ✅	✅ / ✅
fj-kmeans	25	✅ / ✅	✅ / ✅	1 / 2	1309 / 1292	✅ / ✅	✅ / ✅
future-genetic	21	✅ / ✅	✅ / ✅	2 / 2	2935 / 2923	✅ / ✅	✅ / ✅
future-genetic	25	✅ / ✅	✅ / ✅	2 / 1	2825 / 2908	✅ / ✅	✅ / ✅
naive-bayes	21	✅ / ✅	✅ / ✅	5 / 4	3535 / 3528	✅ / ✅	✅ / ✅
naive-bayes	25	✅ / ✅	✅ / ✅	4 / 6	3515 / 3473	✅ / ✅	✅ / ✅
reactors	21	✅ / ✅	✅ / ✅	1 / 1	1706 / 1935	✅ / ✅	✅ / ✅
reactors	25	✅ / ✅	✅ / ✅	✅ / ✅	1880 / 1862	✅ / ✅	✅ / ✅

kaahos and others added 2 commits July 16, 2026 15:13

feat(wall): add configurable wall thread scope

e0a3aa8

Merge branch 'main' into paul.fournillon/wallclock-all-threads

8b014d4

fix: fix test all threads

c5c80a1

kaahos force-pushed the paul.fournillon/taskblock-jvm-producers branch 2 times, most recently from 1beeda2 to 38efbf8 Compare July 16, 2026 15:20

kaahos and others added 5 commits July 17, 2026 00:12

Merge branch 'main' into paul.fournillon/wallclock-all-threads

4f88000

feat(taskblock): capture stacks synchronously at block exit

67109c4

test: scope precheck workloads to all threads

7b73ddb

fix: restrict block suppression to all-thread scope

a510274

fix: preserve JVMTI frames in overlapping buffers

65ca596

kaahos force-pushed the paul.fournillon/taskblock-jvm-producers branch from 38efbf8 to cdb8274 Compare July 16, 2026 22:13

kaahos added 4 commits July 17, 2026 11:32

test: compare precheck counter delta

80d9909

feat(taskblock): add JVM blocking producers

d3f9595

test: verify JVM producers in all-thread scope

47adc9c

test: register context-scope mitigation threads

c111812

kaahos force-pushed the paul.fournillon/taskblock-jvm-producers branch from e13ec27 to c111812 Compare July 17, 2026 09:43

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feat: emit TaskBlock events for JVM blocking states#665

feat: emit TaskBlock events for JVM blocking states#665
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Benchmark Results (commit `cdb8274`)

Benchmark Results (commit `e13ec27`)

Benchmark Results (commit `c111812`)