fix(trace-agent): guard against nil chunk Tags on v0.7 payloads - #54666
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A v0.7 trace chunk that omits the "tags" key decodes with a nil Tags map, because TraceChunk.UnmarshalMsg allocates the map only inside the "tags" field case. setChunkAttributes then promotes a span-level _dd.p.dm into chunk.Tags without a nil check, panicking with "assignment to entry in nil map". Allocate the map before the write in setChunkAttributes, and establish a non-nil chunk Tags invariant at decode time in normalizeDecodedPayload (renamed from removeNilEntries, which already normalized decoded payloads for the pipeline). The v0.1/v0.4/v0.5 chunk builders already allocate Tags, so this only closes the v0.7 gap. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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🎯 Code Coverage (details) 🔗 Commit SHA: d4d8f75 | Docs | Datadog PR Page | Give us feedback! |
Files inventory check summaryFile checks results against ancestor b39d95df: Results for datadog-agent_7.84.0~devel.git.52.d4d8f75.pipeline.130041339-1_amd64.deb:No change detected Results for datadog-iot-agent_7.84.0~devel.git.52.d4d8f75.pipeline.130041339-1_amd64.deb:No change detected |
Static quality checks✅ Please find below the results from static quality gates 33 successful checks with minimal change (< 2 KiB)
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Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Regression DetectorRegression Detector ResultsMetrics dashboard Baseline: f78d0c6 Optimization Goals: ✅ No significant changes detected
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| perf | experiment | goal | Δ mean % | Δ mean % CI | trials | links |
|---|---|---|---|---|---|---|
| ➖ | quality_gate_idle_all_features | memory utilization | +0.63 | [+0.59, +0.67] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_security_idle | memory utilization | +0.41 | [+0.35, +0.46] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_private_action_runner | memory utilization | +0.20 | [+0.08, +0.32] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_security_mean_fs_load | memory utilization | -0.03 | [-0.07, +0.00] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_idle | memory utilization | -0.08 | [-0.13, -0.03] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_security_no_fs_load | memory utilization | -0.17 | [-0.26, -0.07] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_logs | % cpu utilization | -0.45 | [-1.29, +0.39] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_metrics_logs | memory utilization | -1.22 | [-1.47, -0.97] | 1 | Logs bounds checks dashboard |
Bounds Checks: ✅ Passed
| perf | experiment | bounds_check_name | replicates_passed | observed_value | links |
|---|---|---|---|---|---|
| ✅ | quality_gate_idle | intake_connections | 10/10 | 3 ≤ 4 | bounds checks dashboard |
| ✅ | quality_gate_idle | memory_usage | 10/10 | 148.37MiB ≤ 154MiB | bounds checks dashboard |
| ✅ | quality_gate_idle | total_bytes_received | 10/10 | 731.62KiB ≤ 819.20KiB | bounds checks dashboard |
| ✅ | quality_gate_idle_all_features | intake_connections | 10/10 | 3 ≤ 4 | bounds checks dashboard |
| ✅ | quality_gate_idle_all_features | memory_usage | 10/10 | 495.76MiB ≤ 512MiB | bounds checks dashboard |
| ✅ | quality_gate_idle_all_features | total_bytes_received | 10/10 | 1.12MiB ≤ 1.25MiB | bounds checks dashboard |
| ✅ | quality_gate_logs | intake_connections | 10/10 | 18 ≤ 40 | bounds checks dashboard |
| ✅ | quality_gate_logs | memory_usage | 10/10 | 185.70MiB ≤ 195MiB | bounds checks dashboard |
| ✅ | quality_gate_logs | missed_bytes | 10/10 | 0B = 0B | bounds checks dashboard |
| ✅ | quality_gate_logs | total_bytes_received | 10/10 | 264.16MiB ≤ 292MiB | bounds checks dashboard |
| ✅ | quality_gate_metrics_logs | cpu_usage | 10/10 | 371.01 ≤ 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 | 375.92MiB ≤ 430MiB | 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 | 72.16MiB ≤ 75MiB | bounds checks dashboard |
| ✅ | quality_gate_security_idle | cpu_usage | 10/10 | 28.99 ≤ 100 | bounds checks dashboard |
| ✅ | quality_gate_security_idle | memory_usage | 10/10 | 300.93MiB ≤ 330MiB | bounds checks dashboard |
| ✅ | quality_gate_security_mean_fs_load | cpu_usage | 10/10 | 58.96 ≤ 200 | bounds checks dashboard |
| ✅ | quality_gate_security_mean_fs_load | memory_usage | 10/10 | 281.33MiB ≤ 310MiB | bounds checks dashboard |
| ✅ | quality_gate_security_no_fs_load | cpu_usage | 10/10 | 25.89 ≤ 100 | bounds checks dashboard |
| ✅ | quality_gate_security_no_fs_load | memory_usage | 10/10 | 288.01MiB ≤ 320MiB | 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:
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Its estimated |Δ mean %| ≥ 5.00%, indicating the change is big enough to merit a closer look.
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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.
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Its configuration does not mark it "erratic".
Replicate Execution Details
We run multiple replicates for each experiment/variant. However, we allow replicates to be automatically retried if there are any failures, up to 8 times, at which point the replicate is marked dead and we are unable to run analysis for the entire experiment. We call each of these attempts at running replicates a replicate execution. This section lists all replicate executions that failed due to the target crashing or being oom killed.
Note: In the below tables we bucket failures by experiment, variant, and failure type. For each of these buckets we list out the replicate indexes that failed with an annotation signifying how many times said replicate failed with the given failure mode. In the below example the baseline variant of the experiment named experiment_with_failures had two replicates that failed by oom kills. Replicate 0, which failed 8 executions, and replicate 1 which failed 6 executions, all with the same failure mode.
| Experiment | Variant | Replicates | Failure | Logs | Debug Dashboard |
|---|---|---|---|---|---|
| experiment_with_failures | baseline | 0 (x8) 1 (x6) | Oom killed | Debug Dashboard |
The debug dashboard links will take you to a debugging dashboard specifically designed to investigate replicate execution failures.
❌ Retried Profiling Replicate Execution Failures (ddprof)
Note: Profiling replicas may still be executing. See the debug dashboard for up to date status.
| Experiment | Variant | Replicates | Failure | Debug Dashboard |
|---|---|---|---|---|
| quality_gate_idle_all_features | baseline | 10 | Oom killed | Debug Dashboard |
| quality_gate_idle_all_features | comparison | 10 | Oom killed | Debug Dashboard |
| quality_gate_logs | comparison | 10 | Oom killed | Debug Dashboard |
| quality_gate_metrics_logs | baseline | 10 | Oom killed | Debug Dashboard |
| quality_gate_metrics_logs | comparison | 10 | Oom killed | Debug Dashboard |
| quality_gate_security_mean_fs_load | baseline | 10 | Crashed (exit code: 134) | Debug Dashboard |
| quality_gate_security_no_fs_load | baseline | 10 | Oom killed | Debug Dashboard |
| quality_gate_security_no_fs_load | comparison | 10 | Oom killed | Debug Dashboard |
CI Pass/Fail Decision
✅ Passed. All Quality Gates passed.
- quality_gate_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
- quality_gate_idle, bounds check intake_connections: 10/10 replicas passed. Gate passed.
- quality_gate_idle, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
- quality_gate_idle_all_features, bounds check total_bytes_received: 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 memory_usage: 10/10 replicas passed. Gate passed.
- quality_gate_security_idle, 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_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_private_action_runner, bounds check memory_usage: 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 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 memory_usage: 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 intake_connections: 10/10 replicas passed. Gate passed.
- quality_gate_logs, bounds check missed_bytes: 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 memory_usage: 10/10 replicas passed. Gate passed.
- quality_gate_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
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### What does this PR do? Fixes a `panic: assignment to entry in nil map` in the trace-agent when it processes a v0.7 payload whose trace chunk omits the `tags` key. Two changes: 1. `setChunkAttributes` (`pkg/trace/agent/normalizer.go`) allocates `chunk.Tags` before promoting a span-level `_dd.p.dm` into it. 2. `removeNilEntries` (`pkg/trace/api/api.go`) is renamed to `normalizeDecodedPayload` and now also guarantees a non-nil `Tags` map on every retained chunk, so downstream code can rely on the invariant. ### Motivation Nil tags could trigger a panic where later code assumed the map would be non-nil ### Describe how you validated your changes Two regression tests, both of which panic without the fix and existing tests Co-authored-by: andrew.glaude <andrew.glaude@datadoghq.com> a055712
What does this PR do?
Fixes a
panic: assignment to entry in nil mapin the trace-agent when it processes a v0.7 payload whose trace chunk omits thetagskey.Two changes:
setChunkAttributes(pkg/trace/agent/normalizer.go) allocateschunk.Tagsbefore promoting a span-level_dd.p.dminto it.removeNilEntries(pkg/trace/api/api.go) is renamed tonormalizeDecodedPayloadand now also guarantees a non-nilTagsmap on every retained chunk, so downstream code can rely on the invariant.Motivation
Nil tags could trigger a panic where later code assumed the map would be non-nil
Describe how you validated your changes
Two regression tests, both of which panic without the fix and existing tests