OpenClaw Test Heap Leaks

Use this skill for test-memory investigations. Do not guess from RSS alone when heap snapshots are available.

Workflow

1. Reproduce the failing shape first.

   • Match the real entrypoint if possible. For Linux CI-style unit failures, start with:
   • pnpm canvas:a2ui:bundle && OPENCLAW_TEST_MEMORY_TRACE=1 OPENCLAW_TEST_HEAPSNAPSHOT_INTERVAL_MS=60000 OPENCLAW_TEST_HEAPSNAPSHOT_DIR=.tmp/heapsnap OPENCLAW_TEST_WORKERS=2 OPENCLAW_TEST_MAX_OLD_SPACE_SIZE_MB=6144 pnpm test
   • Keep OPENCLAW_TEST_MEMORY_TRACE=1 enabled so the wrapper prints per-file RSS summaries alongside the snapshots.
   • If the report is about a specific shard or worker budget, preserve that shape.

2. Wait for repeated snapshots before concluding anything.

   • Take at least two intervals from the same lane.
   • Compare snapshots from the same PID inside one lane directory such as .tmp/heapsnap/unit-fast/.
   • Use scripts/heapsnapshot-delta.mjs to compare either two files directly or the earliest/latest pair per PID in one lane directory.

3. Classify the growth before choosing a fix.

   • If growth is dominated by Vite/Vitest transformed source strings, Module, system / Context, bytecode, descriptor arrays, or property maps, treat it as retained module graph growth in long-lived workers.
   • If growth is dominated by app objects, caches, buffers, server handles, timers, mock state, sqlite state, or similar runtime objects, treat it as a likely cleanup or lifecycle leak.

4. Fix the right layer.

   • For retained transformed-module growth in shared workers:
   • Move hotspot files out of unit-fast by updating test/fixtures/test-parallel.behavior.json.
   • Prefer singletonIsolated for files that are safe alone but inflate shared worker heaps.
   • If the file should already have been peeled out by timings but is absent from test/fixtures/test-timings.unit.json, call that out explicitly. Missing timings are a scheduling blind spot.
   • For real leaks:
   • Patch the implicated test or runtime cleanup path.
   • Look for missing afterEach/afterAll, module-reset gaps, retained global state, unreleased DB handles, or listeners/timers that survive the file.

5. Verify with the most direct proof.

   • Re-run the targeted lane or file with heap snapshots enabled if the suite still finishes in reasonable time.
   • If snapshot overhead pushes tests over Vitest timeouts, fall back to the same lane without snapshots and confirm the RSS trend or OOM is reduced.
   • For wrapper-only changes, at minimum verify the expected lanes start and the snapshot files are written.

Heuristics

• Do not call everything a leak. In this repo, large unit-fast growth can be a worker-lifetime problem rather than an application object leak.
• scripts/test-parallel.mjs and scripts/test-parallel-memory.mjs are the primary control points for wrapper diagnostics.
• The lane names printed by [test-parallel] start ... and [test-parallel][mem] summary ... tell you where to focus.
• When one or two files account for most of the delta and they are missing from timings, reducing impact by isolating them is usually the first pragmatic fix.
• When the same retained object families grow across multiple intervals in the same worker PID, trust the snapshots over intuition.

Snapshot Comparison

• Direct comparison:
  • node .agents/skills/openclaw-test-heap-leaks/scripts/heapsnapshot-delta.mjs before.heapsnapshot after.heapsnapshot
• Auto-select earliest/latest snapshots per PID within one lane:
  • node .agents/skills/openclaw-test-heap-leaks/scripts/heapsnapshot-delta.mjs --lane-dir .tmp/heapsnap/unit-fast
• Useful flags:
  • --top 40
  • --min-kb 32
  • --pid 16133

Read the top positive deltas first. Large positive growth in module-transform artifacts suggests lane isolation; large positive growth in runtime objects suggests a real leak.

Output Expectations

When using this skill, report:

• The exact reproduce command.
• Which lane and PID were compared.
• The dominant retained object families from the snapshot delta.
• Whether the issue is a real leak or shared-worker retained module growth.
• The concrete fix or impact-reduction patch.
• What you verified, and what snapshot overhead prevented you from verifying.