fix(cws): read the Node.js record slot offset from the discovery struct

[danielmercier]

What does this PR do?

Reads the JSObject record slot offset from the per-thread otel_thread_ctx_nodejs_v1 discovery struct, instead of hardcoding it, and drops the unused offset attributes from the test writer.

Motivation

The offset is 24 bytes on Node.js 22 and 32 on Node.js 23+, so the writer now publishes it per thread (DataDog/pprof-nodejs#421).

[github-actions]

AI review by Codex (OpenAI) - workflow run

The patch is correct. The reader uses the per-thread record slot offset, and the updated discovery struct preserves its size and field alignment. No actionable regressions found. The C fixture passes syntax checking; runtime tests were not run, and offset 32 lacks fixture coverage.

[github-actions]

AI review by Codex (OpenAI) - workflow run

The patch is correct. The reader now uses the per-thread record slot offset, and the C layout, Go serialization, and test writer remain consistent. No actionable issues found. Validation was limited to code inspection; tests were not run.

[datadog-datadog-us1-prod]

🎯 Code Coverage (details)
• Patch Coverage: 100.00%
• Overall Coverage: 58.39% (+0.00%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: b529f8d | Docs | Give us feedback!}

[dd-octo-sts]

Files inventory check summary

File checks results against ancestor 1f15fe99:

Results for datadog-agent_7.85.0~devel.git.948.b529f8d.pipeline.141855656-1_amd64.deb:

No change detected

Results for datadog-iot-agent_7.85.0~devel.git.948.b529f8d.pipeline.141855656-1_amd64.deb:

No change detected

[dd-octo-sts]

Static quality checks

✅ Please find below the results from static quality gates
Comparison made with ancestor 1f15fe9
📊 Static Quality Gates Dashboard
🔗 SQG Job

33 successful checks with minimal change (< 2 KiB)

	Quality gate	Current Size
✅	agent_deb_amd64	774.785 MiB
✅	agent_deb_amd64_fips	707.893 MiB
✅	agent_heroku_amd64	319.059 MiB
✅	agent_msi	652.989 MiB
✅	agent_rpm_amd64	774.769 MiB
✅	agent_rpm_amd64_fips	707.877 MiB
✅	agent_rpm_arm64	745.630 MiB
✅	agent_rpm_arm64_fips	684.291 MiB
✅	agent_suse_amd64	774.769 MiB
✅	agent_suse_amd64_fips	707.877 MiB
✅	agent_suse_arm64	745.630 MiB
✅	agent_suse_arm64_fips	684.291 MiB
✅	docker_agent_amd64	831.016 MiB
✅	docker_agent_arm64	826.500 MiB
✅	docker_agent_jmx_amd64	1021.886 MiB
✅	docker_agent_jmx_arm64	1006.150 MiB
✅	docker_cws_instrumentation_amd64	7.439 MiB
✅	docker_cws_instrumentation_arm64	6.877 MiB
✅	docker_dogstatsd_amd64	39.468 MiB
✅	docker_dogstatsd_arm64	37.566 MiB
✅	docker_host_profiler_amd64	308.220 MiB
✅	docker_host_profiler_arm64	319.382 MiB
✅	dogstatsd_deb_amd64	30.214 MiB
✅	dogstatsd_deb_arm64	28.222 MiB
✅	dogstatsd_rpm_amd64	30.214 MiB
✅	dogstatsd_suse_amd64	30.214 MiB
✅	iot_agent_deb_amd64	46.785 MiB
✅	iot_agent_deb_arm64	43.391 MiB
✅	iot_agent_deb_armhf	44.218 MiB
✅	iot_agent_rpm_amd64	46.786 MiB
✅	iot_agent_suse_amd64	46.785 MiB
✅	docker_cluster_agent_amd64	213.208 MiB
✅	docker_cluster_agent_arm64	226.161 MiB

[cit-pr-commenter-54b7da]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Job ID: 4ef3adce-29b7-44e3-90d2-cdbbf425537b

Baseline: f4c89a9
Comparison: 8ccaee6
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	dsd_uds_10mb_3k_timestamped_contexts_cpu	% cpu utilization	+1.25	[+1.02, +1.48]	1	Logs
➖	quality_gate_metrics_logs	memory utilization	+1.16	[+0.93, +1.39]	1	Logs bounds checks dashboard
➖	dsd_uds_10mb_3k_timestamped_contexts_memory	memory utilization	+0.82	[+0.59, +1.05]	1	Logs
➖	quality_gate_security_mean_fs_load	memory utilization	+0.22	[+0.17, +0.26]	1	Logs bounds checks dashboard
➖	quality_gate_idle_all_features	memory utilization	+0.20	[+0.13, +0.28]	1	Logs bounds checks dashboard
➖	python_openmetrics	% cpu utilization	+0.11	[-0.57, +0.79]	1	Logs bounds checks dashboard
➖	quality_gate_idle	memory utilization	-0.06	[-0.10, -0.01]	1	Logs bounds checks dashboard
➖	quality_gate_security_idle	memory utilization	-0.09	[-0.13, -0.05]	1	Logs bounds checks dashboard
➖	quality_gate_private_action_runner	memory utilization	-0.39	[-0.52, -0.27]	1	Logs bounds checks dashboard
➖	quality_gate_security_no_fs_load	memory utilization	-0.41	[-0.47, -0.34]	1	Logs bounds checks dashboard
➖	quality_gate_logs	% cpu utilization	-1.11	[-1.96, -0.26]	1	Logs bounds checks dashboard
➖	dsd_uds_client_drop_detector_cpu	% cpu utilization	-1.70	[-2.20, -1.20]	1	Logs

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	observed_value	links
✅	python_openmetrics	checks_execution_time	10/10	81.15 ≤ 100	bounds checks dashboard
✅	python_openmetrics	cpu_usage	10/10	1332.34 ≤ 1500	bounds checks dashboard
✅	python_openmetrics	memory_usage	10/10	4.33GiB ≤ 4.75GiB	bounds checks dashboard
✅	quality_gate_idle	intake_connections	10/10	4 ≤ 5	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	174.02MiB ≤ 181MiB	bounds checks dashboard
✅	quality_gate_idle	total_bytes_received	10/10	755.30KiB ≤ 819.20KiB	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	2 ≤ 5	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	471.29MiB ≤ 542MiB	bounds checks dashboard
✅	quality_gate_idle_all_features	total_bytes_received	10/10	1.13MiB ≤ 1.25MiB	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10	20 ≤ 40	bounds checks dashboard
✅	quality_gate_logs	memory_usage	10/10	212.99MiB ≤ 228MiB	bounds checks dashboard
✅	quality_gate_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_logs	total_bytes_received	10/10	263.12MiB ≤ 292MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	cpu_usage	10/10	366.31 ≤ 2000	bounds checks dashboard
✅	quality_gate_metrics_logs	intake_connections	10/10	18 ≤ 40	bounds checks dashboard
✅	quality_gate_metrics_logs	memory_usage	10/10	453.62MiB ≤ 455MiB	bounds checks dashboard
✅	quality_gate_metrics_logs	missed_bytes	10/10	0B = 0B	bounds checks dashboard
✅	quality_gate_metrics_logs	total_bytes_received	10/10	0.94GiB ≤ 1.04GiB	bounds checks dashboard
✅	quality_gate_private_action_runner	memory_usage	10/10	73.39MiB ≤ 75MiB	bounds checks dashboard
✅	quality_gate_security_idle	cpu_usage	10/10	29.66 ≤ 100	bounds checks dashboard
✅	quality_gate_security_idle	memory_usage	10/10	324.42MiB ≤ 357MiB	bounds checks dashboard
✅	quality_gate_security_mean_fs_load	cpu_usage	10/10	65.27 ≤ 200	bounds checks dashboard
✅	quality_gate_security_mean_fs_load	memory_usage	10/10	311.68MiB ≤ 337MiB	bounds checks dashboard
✅	quality_gate_security_no_fs_load	cpu_usage	10/10	24.35 ≤ 100	bounds checks dashboard
✅	quality_gate_security_no_fs_load	memory_usage	10/10	311.60MiB ≤ 348MiB	bounds checks dashboard

Explanation

Confidence level: 90.00%
Effect size tolerance: |Δ mean %| ≥ 5.00%

Performance changes are noted in the perf column of each table:

• ✅ = significantly better comparison variant performance
• ❌ = significantly worse comparison variant performance
• ➖ = no significant change in performance

A regression test is an A/B test of target performance in a repeatable rig, where "performance" is measured as "comparison variant minus baseline variant" for an optimization goal (e.g., ingress throughput). Due to intrinsic variability in measuring that goal, we can only estimate its mean value for each experiment; we report uncertainty in that value as a 90.00% confidence interval denoted "Δ mean % CI".

For each experiment, we decide whether a change in performance is a "regression" -- a change worth investigating further -- if all of the following criteria are true:

1. Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.

2. Its 90.00% confidence interval "Δ mean % CI" does not contain zero, indicating that if our statistical model is accurate, there is at least a 90.00% chance there is a difference in performance between baseline and comparison variants.

3. Its configuration does not mark it "erratic".

CI Pass/Fail Decision

✅ Passed. All Quality Gates passed.

• quality_gate_private_action_runner, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_idle, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle_all_features, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_security_mean_fs_load, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_mean_fs_load, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_metrics_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check missed_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_security_no_fs_load, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_security_no_fs_load, bounds check cpu_usage: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
• quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.

[temporal-github-worker-1]

Backport evaluation: View Slack thread