[usm] reliability, preparation for pool of objects, Protocol.ReleaseStats()

[yuri-lipnesh]

What does this PR do?

It adds usm Protocol.ReleaseStats() to release reported stats objects.
It introduces a chain of functions to invoke ReleaseStats(), starting from the network tracer.
The HTTP handler retains and implicitly releases references to the reported statistics.

Motivation

This is part of the ongoing reliability effort, serving as a preparation step for adding a pool of DDSketch objects.
It breaks the task of implementing the object pool into two distinct phases.

Describe how you validated your changes

Unit tests.
Running usm http load tests.

Possible Drawbacks / Trade-offs

Additional Notes

[agent-platform-auto-pr]

Test changes on VM

Use this command from test-infra-definitions to manually test this PR changes on a VM:

inv aws.create-vm --pipeline-id=51139447 --os-family=ubuntu

Note: This applies to commit 3e43c34

[agent-platform-auto-pr]

Package size comparison

Comparison with ancestor c8198112b365071ad0b9c4040caca451808215a2

Diff per package

package	diff	status	size	ancestor	threshold
datadog-agent-amd64-deb	-1.41MB	✅	1268.87MB	1270.28MB	140.00MB
datadog-iot-agent-amd64-deb	0.00MB	✅	113.29MB	113.29MB	10.00MB
datadog-dogstatsd-amd64-deb	0.00MB	✅	78.52MB	78.52MB	10.00MB
datadog-heroku-agent-amd64-deb	-1.40MB	✅	505.43MB	506.83MB	70.00MB
datadog-agent-x86_64-rpm	-1.41MB	✅	1278.10MB	1279.51MB	140.00MB
datadog-agent-x86_64-suse	-1.41MB	✅	1278.10MB	1279.51MB	140.00MB
datadog-iot-agent-x86_64-rpm	0.00MB	✅	113.35MB	113.35MB	10.00MB
datadog-iot-agent-x86_64-suse	0.00MB	✅	113.35MB	113.35MB	10.00MB
datadog-dogstatsd-x86_64-rpm	0.00MB	✅	78.59MB	78.59MB	10.00MB
datadog-dogstatsd-x86_64-suse	0.00MB	✅	78.59MB	78.59MB	10.00MB
datadog-agent-arm64-deb	-1.40MB	✅	1003.94MB	1005.34MB	140.00MB
datadog-iot-agent-arm64-deb	0.00MB	✅	108.76MB	108.76MB	10.00MB
datadog-dogstatsd-arm64-deb	0.00MB	✅	55.74MB	55.74MB	10.00MB
datadog-agent-aarch64-rpm	-1.40MB	✅	1013.16MB	1014.56MB	140.00MB
datadog-iot-agent-aarch64-rpm	0.00MB	✅	108.83MB	108.83MB	10.00MB

Decision

✅ Passed

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: 0c4778eb-c893-4a71-905e-9045a492d185

Baseline: c819811
Comparison: 3e43c34
Diff

Optimization Goals: ✅ No significant changes detected

Fine details of change detection per experiment

perf	experiment	goal	Δ mean %	Δ mean % CI	trials	links
➖	quality_gate_logs	% cpu utilization	+0.44	[-2.52, +3.41]	1	Logs
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	+0.16	[-0.30, +0.62]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+0.16	[-0.57, +0.88]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.07	[-0.86, +1.00]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	+0.03	[-0.60, +0.66]	1	Logs
➖	file_to_blackhole_0ms_latency_http2	egress throughput	+0.02	[-0.84, +0.88]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.02	[-0.08, +0.11]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	+0.00	[-0.01, +0.01]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	-0.00	[-0.74, +0.74]	1	Logs
➖	file_to_blackhole_0ms_latency_http1	egress throughput	-0.03	[-0.94, +0.88]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	-0.08	[-0.86, +0.70]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	-0.10	[-0.87, +0.66]	1	Logs
➖	file_tree	memory utilization	-0.31	[-0.44, -0.19]	1	Logs
➖	quality_gate_idle	memory utilization	-0.39	[-0.44, -0.34]	1	Logs bounds checks dashboard
➖	tcp_syslog_to_blackhole	ingress throughput	-0.71	[-0.77, -0.65]	1	Logs
➖	otel_to_otel_logs	ingress throughput	-1.58	[-2.28, -0.88]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	-1.97	[-2.09, -1.84]	1	Logs bounds checks dashboard

Bounds Checks: ✅ Passed

perf	experiment	bounds_check_name	replicates_passed	links
✅	file_to_blackhole_0ms_latency	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency	memory_usage	10/10
✅	file_to_blackhole_0ms_latency_http1	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency_http1	memory_usage	10/10
✅	file_to_blackhole_0ms_latency_http2	lost_bytes	10/10
✅	file_to_blackhole_0ms_latency_http2	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency	memory_usage	10/10
✅	file_to_blackhole_1000ms_latency_linear_load	memory_usage	10/10
✅	file_to_blackhole_100ms_latency	lost_bytes	10/10
✅	file_to_blackhole_100ms_latency	memory_usage	10/10
✅	file_to_blackhole_300ms_latency	lost_bytes	10/10
✅	file_to_blackhole_300ms_latency	memory_usage	10/10
✅	file_to_blackhole_500ms_latency	lost_bytes	10/10
✅	file_to_blackhole_500ms_latency	memory_usage	10/10
✅	quality_gate_idle	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_logs	lost_bytes	10/10
✅	quality_gate_logs	memory_usage	10/10

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_idle, bounds check memory_usage: 10/10 replicas passed. Gate passed.
• quality_gate_logs, bounds check lost_bytes: 10/10 replicas passed. Gate passed.
• quality_gate_logs, 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.