feat: add core TaskBlock event recording support#664
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CI Test ResultsRun: #29839633478 | Commit:
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Legend: ✅ passed | ❌ failed | ⚪ skipped | 🚫 cancelled Summary: Total: 32 | Passed: 32 | Failed: 0 Updated: 2026-07-21 14:52:07 UTC |
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Reliability & Chaos Results✅ All reliability & chaos checks passed Pipeline: https://gitlab.ddbuild.io/DataDog/java-profiler/-/pipelines/125161957 |
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Pull request overview
Adds first-class TaskBlock event recording to the Java profiler so known blocking intervals can be emitted directly (without relying on wall-clock sampling signals), including native/JFR plumbing and updates to wall-precheck behavior and tests.
Changes:
- Introduces public Java API
beginTaskBlock(int)/endTaskBlock(long, long, long)and native recording pipeline fordatadog.TaskBlock. - Reworks wall-precheck suppression around lifecycle-owned blocked runs, including unfiltered registry tracking and bounded “lazy backfill” candidate selection.
- Expands unit/integration/benchmark coverage for unfiltered precheck, restart safety, JVMTI delegation, and TaskBlock behavior.
Reviewed changes
Copilot reviewed 51 out of 51 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/WallclockMitigationsCombinedTest.java | Updates combined mitigation assertions to ensure context-scoped threads remain sampled and suppression counters don’t change. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/UnfilteredWallPrecheckTest.java | Adds integration coverage for owned-block prechecks when filter= samples every thread. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/UnfilteredWallPrecheckRestartTest.java | Adds restart/epoch safety coverage for unfiltered tracking across multiple recordings. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/TaskBlockAssertions.java | Adds JMC-based assertion helpers for datadog.TaskBlock contract validation. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/PrecheckTest.java | Updates precheck tests to new suppression semantics/counters and explicit filter= behavior. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/PrecheckEfficiencyTest.java | Adjusts workload tests to align with new lifecycle-owned suppression and explicit unfiltered sampling. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/JvmtiBasedUnfilteredWallPrecheckTest.java | Adds JVMTI-delegated stack path coverage for unfiltered owned-block precheck. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/JvmtiBasedPrecheckTest.java | Aligns JVMTI precheck tests with explicit filter= commands. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/JavaProfilerTaskBlockPreExistingThreadTest.java | Verifies TaskBlock TLS init for threads created before profiler startup. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/JavaProfilerTaskBlockDisabledTest.java | Verifies TaskBlock API stays inactive when not in all-thread scope. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/JavaProfilerTaskBlockApiTest.java | End-to-end coverage for paired TaskBlock API, nesting/token rules, context admission, vthreads, and live dump behavior. |
| ddprof-test/src/test/java/com/datadoghq/profiler/wallclock/J9WallClockPrecheckCapabilityTest.java | Ensures unsupported J9 wall engine doesn’t activate unfiltered precheck tracking. |
| ddprof-test/src/test/java/com/datadoghq/profiler/JavaProfilerApiSurfaceTest.java | Verifies TaskBlock API is public while internal hooks remain non-public. |
| ddprof-test/src/test/java/com/datadoghq/profiler/context/OtelContextStorageModeTest.java | Ensures trace context is cleared during cleanup (ordering with reset). |
| ddprof-test/src/test/java/com/datadoghq/profiler/context/AllNativeContextTest.java | Ensures trace context is cleared during cleanup (ordering with reset). |
| ddprof-test/src/test/java/com/datadoghq/profiler/AbstractProfilerTest.java | Adds beforeProfilerStart() hook and clears trace context on stopProfiler(). |
| ddprof-stresstest/src/jmh/java/com/datadoghq/profiler/WallClockPrecheckBenchmarkHooks.java | Exposes package-scoped hooks for benchmarking owned-block precheck overhead. |
| ddprof-stresstest/src/jmh/java/com/datadoghq/profiler/stresstest/scenarios/throughput/WallClockPrecheckOverheadBenchmark.java | Adds JMH benchmark for steady-state wall timer overhead vs. owned-block population size. |
| ddprof-lib/src/test/cpp/wallprecheck_args_ut.cpp | Adds engine capability and filter= parsing regression tests. |
| ddprof-lib/src/test/cpp/wallClockCounters_ut.cpp | Renames/updates suppression counter tests to owned-block suppression. |
| ddprof-lib/src/test/cpp/wallClockCandidateSelector_ut.cpp | Adds unit tests for bounded candidate selection/backfill logic. |
| ddprof-lib/src/test/cpp/threadFilter_ut.cpp | Expands ThreadFilter tests for registry, epoch, token encoding, and owned-block suppression eligibility. |
| ddprof-lib/src/test/cpp/taskBlockRecorder_ut.cpp | Adds unit tests for TaskBlock eligibility, rotation, and record/stack failure accounting. |
| ddprof-lib/src/test/cpp/park_state_ut.cpp | Updates tests to owned-block state semantics and slot-reset expectations. |
| ddprof-lib/src/test/cpp/jvmSupport_ut.cpp | Adds unit tests for platform vs. virtual thread classification via JNI table probing. |
| ddprof-lib/src/test/cpp/frame_ut.cpp | Adds unit test for copyJvmtiFrames() union-overlap safety. |
| ddprof-lib/src/main/java/com/datadoghq/profiler/JavaProfiler.java | Adds public TaskBlock API and native bindings; clarifies internal hook comments. |
| ddprof-lib/src/main/cpp/wallClockCounters.h | Renames suppressed-sample counter to owned-block suppression counter. |
| ddprof-lib/src/main/cpp/wallClockCandidateSelector.h | Introduces bounded randomized candidate selection with precheck-rejection backfill. |
| ddprof-lib/src/main/cpp/wallClock.h | Integrates candidate selector + new suppression counters and visit budgeting. |
| ddprof-lib/src/main/cpp/wallClock.cpp | Reworks precheck suppression to use ThreadFilter-owned block eligibility and optional lazy backfill/lookup accounting. |
| ddprof-lib/src/main/cpp/threadLocalData.h | Adds per-thread TaskBlock lifecycle state in TLS. |
| ddprof-lib/src/main/cpp/threadFilter.h | Adds registry/unfiltered tracking, epoching, owned-block snapshots/tokens, and suppression eligibility checks. |
| ddprof-lib/src/main/cpp/threadFilter.cpp | Implements registry/TID index, recording epochs, retirement, and owned-block suppression candidate logic. |
| ddprof-lib/src/main/cpp/taskBlockRecorder.h | Adds TaskBlock eligibility checks and recording helper APIs. |
| ddprof-lib/src/main/cpp/taskBlockRecorder.cpp | Implements duration thresholding and basic eligibility helpers. |
| ddprof-lib/src/main/cpp/profiler.h | Adds TaskBlock recording entry points and rotation/inflight coordination. |
| ddprof-lib/src/main/cpp/profiler.cpp | Adds TaskBlock recording implementation, rotation coordination, registry bootstrap for existing threads, and updated filter init semantics. |
| ddprof-lib/src/main/cpp/jvmThread.h | Adds capability query for native thread-id lookup support. |
| ddprof-lib/src/main/cpp/jvmThread.cpp | Implements native thread-id lookup capability helper. |
| ddprof-lib/src/main/cpp/jvmSupport.h | Declares isPlatformThread() helper for virtual thread rejection. |
| ddprof-lib/src/main/cpp/jvmSupport.cpp | Implements JNI table probing to detect virtual threads (JDK 19+). |
| ddprof-lib/src/main/cpp/jfrMetadata.h | Adds new JFR type id for TaskBlock. |
| ddprof-lib/src/main/cpp/jfrMetadata.cpp | Registers datadog.TaskBlock event metadata fields. |
| ddprof-lib/src/main/cpp/javaApi.cpp | Adds native implementations for TaskBlock API + registry-aware filter/add/remove and owned-block hooks. |
| ddprof-lib/src/main/cpp/frames.h | Adds copyJvmtiFrames() helper for overlapping JVMTI/ASGCT frame buffers. |
| ddprof-lib/src/main/cpp/flightRecorder.h | Adds TaskBlock recording entry points in recording/recorder. |
| ddprof-lib/src/main/cpp/flightRecorder.cpp | Implements TaskBlock event serialization and recorder entry. |
| ddprof-lib/src/main/cpp/event.h | Adds TaskBlock event struct; updates wall epoch suppressed counter field name/type usage. |
| ddprof-lib/src/main/cpp/engine.h | Adds wall-engine capability query for unfiltered precheck support. |
| ddprof-lib/src/main/cpp/counters.h | Adds counters for registry lookup budget/retirement and TaskBlock outcomes; renames suppression counter. |
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Benchmark Results (commit ebab4c4)Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125876908 Commit:
|
| Benchmark | JDK | Latest | Dev | Δ (dev vs latest) | Issues L/D |
|---|---|---|---|---|---|
| akka-uct | 21 | ✅ 10309 ms (21 iters) | ✅ 10352 ms (21 iters) | ≈ +0.4% (±11.1%) | — / — |
| akka-uct | 25 | ✅ 8971 ms (24 iters) | ✅ 8823 ms (24 iters) | ≈ -1.6% (±10.5%) | — / — |
| finagle-chirper | 21 | ✅ 5997 ms (33 iters) | ✅ 5974 ms (33 iters) | ≈ -0.4% (±25.4%) | |
| finagle-chirper | 25 | ✅ 5455 ms (36 iters) | ✅ 5469 ms (36 iters) | ≈ +0.3% (±24.6%) | |
| fj-kmeans | 21 | ✅ 2671 ms (69 iters) | ✅ 2788 ms (67 iters) | 🔴 +4.4% | — / — |
| fj-kmeans | 25 | ✅ 2765 ms (68 iters) | ✅ 2778 ms (67 iters) | ≈ +0.5% (±2.8%) | — / — |
| future-genetic | 21 | ✅ 2054 ms (91 iters) | ✅ 2127 ms (88 iters) | 🔴 +3.6% | — / — |
| future-genetic | 25 | ✅ 2027 ms (91 iters) | ✅ 2069 ms (90 iters) | ≈ +2.1% (±2.8%) | — / — |
| naive-bayes | 21 | ✅ 1284 ms (133 iters) | ✅ 1244 ms (137 iters) | ≈ -3.1% (±32.2%) | — / — |
| naive-bayes | 25 | ✅ 1013 ms (169 iters) | ✅ 1017 ms (168 iters) | ≈ +0.4% (±31.6%) | — / — |
| reactors | 21 | ✅ 16291 ms (15 iters) | ✅ 15943 ms (15 iters) | ≈ -2.1% (±8.5%) | — / — |
| reactors | 25 | ✅ 18609 ms (15 iters) | ✅ 18693 ms (15 iters) | ≈ +0.5% (±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 | ✅ / ✅ | ✅ / ✅ | ✅ / 3 | 1885 / 2016 | ✅ / ✅ | ✅ / ✅ |
| akka-uct | 25 | ✅ / ✅ | ✅ / ✅ | 6 / ✅ | 2056 / 2299 | ✅ / ✅ | ✅ / ✅ |
| finagle-chirper | 21 | ✅ / ✅ | ✅ / ✅ | 2 / 1 | 8787 / 8984 | ✅ / ✅ | ✅ / ✅ |
| finagle-chirper | 25 | ✅ / ✅ | ✅ / ✅ | 2 / 1 | 8287 / 8556 | ✅ / ✅ | ✅ / ✅ |
| fj-kmeans | 21 | ✅ / ✅ | ✅ / ✅ | 1 / 2 | 1235 / 1277 | ✅ / ✅ | ✅ / ✅ |
| fj-kmeans | 25 | ✅ / ✅ | ✅ / ✅ | 4 / 3 | 1295 / 1292 | ✅ / ✅ | ✅ / ✅ |
| future-genetic | 21 | ✅ / ✅ | ✅ / ✅ | 2 / 1 | 3001 / 3006 | ✅ / ✅ | ✅ / ✅ |
| future-genetic | 25 | ✅ / ✅ | ✅ / ✅ | ✅ / 1 | 2834 / 2887 | ✅ / ✅ | ✅ / ✅ |
| naive-bayes | 21 | ✅ / ✅ | ✅ / ✅ | 5 / 6 | 3513 / 3477 | ✅ / ✅ | ✅ / ✅ |
| naive-bayes | 25 | ✅ / ✅ | ✅ / ✅ | 2 / ✅ | 3500 / 3460 | ✅ / ✅ | ✅ / ✅ |
| reactors | 21 | ✅ / ✅ | ✅ / ✅ | 3 / ✅ | 1612 / 1583 | ✅ / ✅ | ✅ / ✅ |
| reactors | 25 | ✅ / ✅ | ✅ / ✅ | 3 / 2 | 1916 / 1954 | ✅ / ✅ | ✅ / ✅ |
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Benchmark Results (commit 19cbe47)Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125884549 Commit:
|
| Benchmark | JDK | Latest | Dev | Δ (dev vs latest) | Issues L/D |
|---|---|---|---|---|---|
| akka-uct | 21 | ✅ 10377 ms (21 iters) | ✅ 10184 ms (21 iters) | ≈ -1.9% (±11.2%) | — / — |
| akka-uct | 25 | ✅ 8790 ms (24 iters) | ✅ 8896 ms (24 iters) | ≈ +1.2% (±9.7%) | — / — |
| finagle-chirper | 21 | ✅ 5965 ms (33 iters) | ✅ 5956 ms (33 iters) | ≈ -0.2% (±25.2%) | |
| fj-kmeans | 21 | ✅ 2696 ms (70 iters) | ✅ 2843 ms (66 iters) | 🔴 +5.5% | — / — |
| fj-kmeans | 25 | ✅ 2796 ms (67 iters) | ✅ 2746 ms (68 iters) | ≈ -1.8% (±2.8%) | — / — |
| future-genetic | 21 | ✅ 2052 ms (90 iters) | ✅ 2099 ms (89 iters) | ≈ +2.3% (±2.6%) | — / — |
| future-genetic | 25 | ✅ 2035 ms (91 iters) | ✅ 2047 ms (91 iters) | ≈ +0.6% (±2.7%) | — / — |
| naive-bayes | 21 | ✅ 1224 ms (139 iters) | ✅ 1250 ms (136 iters) | ≈ +2.1% (±33.2%) | — / — |
| naive-bayes | 25 | ✅ 1016 ms (168 iters) | ✅ 1017 ms (168 iters) | ≈ +0.1% (±31.6%) | — / — |
| reactors | 21 | ✅ 16927 ms (15 iters) | ✅ 15621 ms (15 iters) | 🟢 -7.7% | — / — |
| reactors | 25 | ✅ 17980 ms (15 iters) | ✅ 17858 ms (15 iters) | ≈ -0.7% (±6.2%) | — / — |
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 | ✅ / ✅ | ✅ / ✅ | 1 / 2 | 1969 / 1961 | ✅ / ✅ | ✅ / ✅ |
| akka-uct | 25 | ✅ / ✅ | ✅ / ✅ | ✅ / 3 | 2168 / 2325 | ✅ / ✅ | ✅ / ✅ |
| finagle-chirper | 21 | ✅ / ✅ | ✅ / ✅ | 3 / 1 | 8522 / 8623 | ✅ / ✅ | ✅ / ✅ |
| finagle-chirper | 25 | ✅ / ✅ | ✅ / ✅ | 3 / 1 | 8617 / 8387 | ✅ / ✅ | ✅ / ✅ |
| fj-kmeans | 21 | ✅ / ✅ | ✅ / ✅ | 1 / 2 | 1273 / 1252 | ✅ / ✅ | ✅ / ✅ |
| fj-kmeans | 25 | ✅ / ✅ | ✅ / ✅ | 1 / 2 | 1256 / 1264 | ✅ / ✅ | ✅ / ✅ |
| future-genetic | 21 | ✅ / ✅ | ✅ / ✅ | 3 / 1 | 2942 / 2959 | ✅ / ✅ | ✅ / ✅ |
| future-genetic | 25 | ✅ / ✅ | ✅ / ✅ | 1 / 1 | 2855 / 2852 | ✅ / ✅ | ✅ / ✅ |
| naive-bayes | 21 | ✅ / ✅ | ✅ / ✅ | 4 / 2 | 3466 / 3494 | ✅ / ✅ | ✅ / ✅ |
| naive-bayes | 25 | ✅ / ✅ | ✅ / ✅ | 5 / 6 | 3466 / 3473 | ✅ / ✅ | ✅ / ✅ |
| reactors | 21 | ✅ / ✅ | ✅ / ✅ | ✅ / 2 | 1660 / 1623 | ✅ / ✅ | ✅ / ✅ |
| reactors | 25 | ✅ / ✅ | ✅ / ✅ | ✅ / ✅ | 1789 / 1796 | ✅ / ✅ | ✅ / ✅ |
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Benchmark Results (commit 25ba2a3)Pipeline: https://gitlab.ddbuild.io/DataDog/apm-reliability/benchmarking-platform/-/pipelines/125986871 Commit: ✅ Within expected boundariesNo significant runtime deltas (all within run-to-run noise) and no internal-counter outliers. Runtime details (per benchmark × JDK)
Internal counter details (ddprof)ddprof internal counters, latest / dev (✅ = 0, · = unavailable):
|
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What does this PR do?:
Adds the core TaskBlock event emission machinery. Recognized blocked intervals are recorded synchronously at block exit, with native APIs, JFR metadata, counters, and wall precheck integration.
Motivation:
Blocked threads should not need to receive wall-clock signals just to represent blocking time. TaskBlock events let the profiler report known blocking intervals directly.
Additional Notes:
This PR adds the generic recording path only. Concrete JVM and native blocking producers are added in follow-up PRs.
How to test the change?:
Automated coverage includes TaskBlock recorder unit tests, Java API tests, wall precheck behavior, disabled-state behavior, and combined wall-clock mitigation tests.
./.claude/commands/build-and-summarize testDebugFor Datadog employees:
dd:platform-security-reviewskill, or file a request via the PSEC review form).bewairealso runs automatically on every PR.