Prevent leaking received dogstatsd metrics on agent shutdown

[ddrthall]

What does this PR do?

Currently, Dogstatsd will bucket metrics into 10 second intervals and will only push buckets up to intake if said buckets are complete (aka the end of their interval is in the past). This behavior is true even on agent shutdown, meaning the final set of metrics dogstatsd received are generally dropped during shutdown. This PR introduces a new flag that will force Dogstatsd to persist all received metrics on shutdown irregardless of their bucket state.

Motivation

Describe how you validated your changes

Setting up a client that emits a single count metric a second to the dogstatsd server provides an excellent visualization into the dogstatsd flush behavior. With the new flag disabled (current behavior), shutting down this dogstatsd server at any time will always result in the final metric reading in the UI being pegged to 10 for each 10 second interval recorded. Enabling the flag and shutting down at different times will result in the final metric read representing the actual second of shutdown.

Possible Drawbacks / Trade-offs

Additional Notes

[agent-platform-auto-pr]

Uncompressed package size comparison

Comparison with ancestor 6a587c6d80bd51615d37b06fc416ecb088789769

Diff per package

package	diff	status	size	ancestor	threshold
datadog-heroku-agent-amd64-deb	0.01MB	⚠️	456.45MB	456.44MB	0.50MB
datadog-iot-agent-amd64-deb	0.01MB	⚠️	93.84MB	93.83MB	0.50MB
datadog-iot-agent-x86_64-rpm	0.01MB	⚠️	93.91MB	93.90MB	0.50MB
datadog-iot-agent-x86_64-suse	0.01MB	⚠️	93.91MB	93.90MB	0.50MB
datadog-dogstatsd-arm64-deb	0.01MB	⚠️	56.51MB	56.50MB	0.50MB
datadog-dogstatsd-amd64-deb	0.01MB	⚠️	59.02MB	59.02MB	0.50MB
datadog-iot-agent-arm64-deb	0.01MB	⚠️	89.89MB	89.89MB	0.50MB
datadog-iot-agent-aarch64-rpm	0.00MB	✅	89.96MB	89.96MB	0.50MB
datadog-dogstatsd-x86_64-rpm	0.00MB	✅	59.10MB	59.09MB	0.50MB
datadog-dogstatsd-x86_64-suse	0.00MB	✅	59.10MB	59.09MB	0.50MB
datadog-agent-x86_64-rpm	0.00MB	✅	886.93MB	886.92MB	0.50MB
datadog-agent-x86_64-suse	0.00MB	✅	886.93MB	886.92MB	0.50MB
datadog-agent-amd64-deb	0.00MB	✅	877.19MB	877.18MB	0.50MB
datadog-agent-aarch64-rpm	0.00MB	✅	874.69MB	874.69MB	0.50MB
datadog-agent-arm64-deb	0.00MB	✅	864.97MB	864.97MB	0.50MB

Decision

⚠️ Warning

[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=54609417 --os-family=ubuntu

Note: This applies to commit 8a234b5

[cit-pr-commenter]

Regression Detector

Regression Detector Results

Metrics dashboard
Target profiles
Run ID: e9a5fe82-38a4-4802-a8b5-96a606753146

Baseline: 5fe0a05
Comparison: 8a234b5
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	+3.73	[+0.64, +6.83]	1	Logs
➖	uds_dogstatsd_to_api_cpu	% cpu utilization	+2.37	[+1.48, +3.26]	1	Logs
➖	quality_gate_idle_all_features	memory utilization	+0.30	[+0.23, +0.38]	1	Logs bounds checks dashboard
➖	file_tree	memory utilization	+0.26	[+0.20, +0.33]	1	Logs
➖	file_to_blackhole_500ms_latency	egress throughput	+0.22	[-0.57, +1.01]	1	Logs
➖	file_to_blackhole_0ms_latency	egress throughput	+0.09	[-0.81, +0.99]	1	Logs
➖	file_to_blackhole_1000ms_latency	egress throughput	+0.08	[-0.69, +0.85]	1	Logs
➖	file_to_blackhole_100ms_latency	egress throughput	+0.07	[-0.63, +0.77]	1	Logs
➖	file_to_blackhole_0ms_latency_http1	egress throughput	+0.05	[-0.83, +0.93]	1	Logs
➖	uds_dogstatsd_to_api	ingress throughput	+0.00	[-0.29, +0.30]	1	Logs
➖	tcp_dd_logs_filter_exclude	ingress throughput	-0.00	[-0.01, +0.01]	1	Logs
➖	file_to_blackhole_300ms_latency	egress throughput	-0.01	[-0.65, +0.63]	1	Logs
➖	file_to_blackhole_0ms_latency_http2	egress throughput	-0.04	[-0.86, +0.77]	1	Logs
➖	quality_gate_idle	memory utilization	-0.13	[-0.16, -0.10]	1	Logs bounds checks dashboard
➖	file_to_blackhole_1000ms_latency_linear_load	egress throughput	-0.39	[-0.85, +0.08]	1	Logs
➖	tcp_syslog_to_blackhole	ingress throughput	-2.25	[-2.35, -2.15]	1	Logs

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	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	intake_connections	10/10	bounds checks dashboard
✅	quality_gate_idle_all_features	memory_usage	10/10	bounds checks dashboard
✅	quality_gate_logs	intake_connections	10/10
✅	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_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, 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_logs, bounds check intake_connections: 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.