fix(system-probe): protect module loader registry with mutex during Register - #54950
fix(system-probe): protect module loader registry with mutex during Register#54950pgimalac wants to merge 1 commit into
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…egister Register() wrote l.cfg, l.stats, and iterated l.modules without holding the loader mutex, racing with GetStats() which takes the lock and reads l.stats. The expvar server (started before StartServer returns) can serve the /debug/stats endpoint while Register is still in progress. Hold l.Lock() around the writes to l.cfg and l.stats, and snapshot the modules map entries before spawning updateModuleStats goroutines so they don't read the map after unlock. Found via a race-detector-enabled build in staging (see #54333).
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| for range 2000 { | ||
| l.Lock() | ||
| l.cfg = nil | ||
| l.stats = make(map[string]any) | ||
| l.Unlock() | ||
| } |
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This writer acquires the mutex itself, so the test only proves that two explicitly synchronized operations do not race. Reverting Register to its previous unlocked assignments and map iteration would not change this test and it would still pass under the race detector, meaning the regression test does not protect the production fix it claims to validate. Invoke Register with lightweight test factories/dependencies, or extract and exercise the actual initialization helper whose locking is under test.
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🎯 Code Coverage (details) 🔗 Commit SHA: 954ede3 | Docs | Datadog PR Page | Give us feedback! |
Files inventory check summaryFile checks results against ancestor 92f6b05c: Results for datadog-agent_7.84.0~devel.git.224.954ede3.pipeline.131279973-1_amd64.deb:No change detected Results for datadog-iot-agent_7.84.0~devel.git.224.954ede3.pipeline.131279973-1_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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Regression DetectorRegression Detector ResultsMetrics dashboard Baseline: 92f6b05 Optimization Goals: ✅ No significant changes detected
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| perf | experiment | goal | Δ mean % | Δ mean % CI | trials | links |
|---|---|---|---|---|---|---|
| ➖ | quality_gate_security_no_fs_load | memory utilization | +0.28 | [+0.14, +0.42] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_idle | memory utilization | +0.11 | [-0.01, +0.23] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_security_mean_fs_load | memory utilization | +0.09 | [+0.02, +0.17] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_logs | % cpu utilization | +0.02 | [-0.84, +0.88] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_idle_all_features | memory utilization | -0.01 | [-0.05, +0.04] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_metrics_logs | memory utilization | -0.06 | [-0.31, +0.20] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_private_action_runner | memory utilization | -0.10 | [-0.22, +0.03] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_security_idle | memory utilization | -0.16 | [-0.27, -0.05] | 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 | 4 = 4 | bounds checks dashboard |
| ✅ | quality_gate_idle | memory_usage | 10/10 | 172.35MiB ≤ 178MiB | bounds checks dashboard |
| ✅ | quality_gate_idle | total_bytes_received | 10/10 | 746.20KiB ≤ 819.20KiB | bounds checks dashboard |
| ✅ | quality_gate_idle_all_features | intake_connections | 10/10 | 4 = 4 | bounds checks dashboard |
| ✅ | quality_gate_idle_all_features | memory_usage | 10/10 | 522.90MiB ≤ 538MiB | bounds checks dashboard |
| ✅ | quality_gate_idle_all_features | total_bytes_received | 10/10 | 1.14MiB ≤ 1.25MiB | bounds checks dashboard |
| ✅ | quality_gate_logs | intake_connections | 10/10 | 18 ≤ 40 | bounds checks dashboard |
| ✅ | quality_gate_logs | memory_usage | 10/10 | 205.72MiB ≤ 229MiB | bounds checks dashboard |
| ✅ | quality_gate_logs | missed_bytes | 10/10 | 0B = 0B | bounds checks dashboard |
| ✅ | quality_gate_logs | total_bytes_received | 10/10 | 264.22MiB ≤ 292MiB | bounds checks dashboard |
| ✅ | quality_gate_metrics_logs | cpu_usage | 10/10 | 350.81 ≤ 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 | 397.67MiB ≤ 439MiB | 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 | 72.05MiB ≤ 76MiB | bounds checks dashboard |
| ✅ | quality_gate_security_idle | cpu_usage | 10/10 | 26.44 ≤ 100 | bounds checks dashboard |
| ✅ | quality_gate_security_idle | memory_usage | 10/10 | 323.75MiB ≤ 335MiB | bounds checks dashboard |
| ✅ | quality_gate_security_mean_fs_load | cpu_usage | 10/10 | 60.39 ≤ 200 | bounds checks dashboard |
| ✅ | quality_gate_security_mean_fs_load | memory_usage | 10/10 | 304.29MiB ≤ 314MiB | bounds checks dashboard |
| ✅ | quality_gate_security_no_fs_load | cpu_usage | 10/10 | 21.01 ≤ 100 | bounds checks dashboard |
| ✅ | quality_gate_security_no_fs_load | memory_usage | 10/10 | 310.94MiB ≤ 343MiB | 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:
-
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".
CI Pass/Fail Decision
✅ Passed. All Quality Gates passed.
- quality_gate_security_no_fs_load, 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_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 missed_bytes: 10/10 replicas passed. Gate passed.
- quality_gate_logs, bounds check total_bytes_received: 10/10 replicas passed. Gate passed.
- quality_gate_security_mean_fs_load, bounds check cpu_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_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_idle_all_features, bounds check total_bytes_received: 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_metrics_logs, bounds check intake_connections: 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_private_action_runner, bounds check memory_usage: 10/10 replicas passed. Gate passed.
- quality_gate_idle, bounds check memory_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.
1 participant
What does this PR do?
Fixes a data race on the module loader registry:
Register()wrotel.cfg,l.stats, and iteratedl.moduleswithout holding the loader mutex, racing withGetStats()which takes the lock and readsl.stats. The expvar server (started beforeStartServerreturns) can serve the/debug/statsendpoint whileRegisteris still in progress. Now holdsl.Lock()around those writes and snapshots module entries before spawning stats goroutines.Motivation
Fix a race, found via a race-detector-enabled build in staging (see #54333 for context).
Describe how you validated your changes
Added
TestRegisterConcurrentGetStatswhich races concurrent writes tol.cfg/l.stats(simulatingRegister) againstGetStats()calls; fails under-racebefore the fix and passes after (dda inv test --targets=./pkg/system-probe/api/module/... --race).