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AMLII-440 Add command to show top dogstatsd contexts #20548

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merged 12 commits into from
Nov 23, 2023
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What does this PR do?

Add a new command to show current contexts tracked by the dogstatsd aggregator.

Motivation

Help troubleshooting high memory usage by the agent.

Additional Notes

Different from the dogstatsd-stats command, this shows the state of the aggregator, rather than the incoming traffic and thus more useful when troubleshooting memory usage.

As this is mostly interesting when free memory is low and number of contexts is high, write the data into a file rather than passing potentially large amount of data in the api response directly. The file can be removed from the system under pressure and analyzed on a different host even if the pod crashes.

Possible Drawbacks / Trade-offs

Describe how to test/QA your changes

Run the agent and send some dogstatsd traffic to it.

Run agent dogstatsd top and make sure the output matches supplied traffic.

Reviewer's Checklist

  • If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
  • Use the major_change label if your change either has a major impact on the code base, is impacting multiple teams or is changing important well-established internals of the Agent. This label will be use during QA to make sure each team pay extra attention to the changed behavior. For any customer facing change use a releasenote.
  • A release note has been added or the changelog/no-changelog label has been applied.
  • Changed code has automated tests for its functionality.
  • Adequate QA/testing plan information is provided if the qa/skip-qa label is not applied.
  • At least one team/.. label has been applied, indicating the team(s) that should QA this change.
  • If applicable, docs team has been notified or an issue has been opened on the documentation repo.
  • If applicable, the need-change/operator and need-change/helm labels have been applied.
  • If applicable, the k8s/<min-version> label, indicating the lowest Kubernetes version compatible with this feature.
  • If applicable, the config template has been updated.

Different from dogstatsd-stats, this shows the state of the
aggregator, rather than the incoming traffic and thus more useful when
troubleshooting memory usage.

As this is mostly interesting when free memory is low and number of
contexts is high, write the data into a file rather than passing it in
the api response directly. The file can be removed from the system
under pressure and analyzed on a different host even if the pod
crashes.
@vickenty vickenty added this to the 7.50.0 milestone Oct 31, 2023
@vickenty vickenty changed the title Add command to show top dogstatsd contexts AMLII-440 Add command to show top dogstatsd contexts Oct 31, 2023
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cit-pr-commenter bot commented Nov 1, 2023

Go Package Import Differences

Baseline: 9ff294d
Comparison: abb6ba8

binaryosarchchange
agentlinuxamd64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
agentlinuxarm64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
agentwindowsamd64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
agentwindows386
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
agentdarwinamd64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
agentdarwinarm64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
iot-agentlinuxamd64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
iot-agentlinuxarm64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd
heroku-agentlinuxamd64
+1, -0
+github.com/DataDog/datadog-agent/cmd/agent/subcommands/dogstatsd

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pr-commenter bot commented Nov 1, 2023

Bloop Bleep... Dogbot Here

Regression Detector Results

Run ID: 007ab765-2e39-41f4-b2bb-a4c9a4aa04bd
Baseline: 9ff294d
Comparison: abb6ba8
Total datadog-agent CPUs: 7

Explanation

A regression test is an integrated performance test for datadog-agent in a repeatable rig, with varying configuration for datadog-agent. What follows is a statistical summary of a brief datadog-agent run for each configuration across SHAs given above. The goal of these tests are to determine quickly if datadog-agent performance is changed and to what degree by a pull request.

Because a target's optimization goal performance in each experiment will vary somewhat each time it is run, we can only estimate mean differences in optimization goal relative to the baseline target. We express these differences as a percentage change relative to the baseline target, denoted "Δ mean %". These estimates are made to a precision that balances accuracy and cost control. We represent this precision as a 90.00% confidence interval denoted "Δ mean % CI": there is a 90.00% chance that the true value of "Δ mean %" is in that interval.

We decide whether a change in performance is a "regression" -- a change worth investigating further -- if both of the following two criteria are true:

  1. The estimated |Δ mean %| ≥ 5.00%. This criterion intends to answer the question "Does the estimated change in mean optimization goal performance have a meaningful impact on your customers?". We assume that when |Δ mean %| < 5.00%, the impact on your customers is not meaningful. We also assume that a performance change in optimization goal is worth investigating whether it is an increase or decrease, so long as the magnitude of the change is sufficiently large.

  2. Zero is not in the 90.00% confidence interval "Δ mean % CI" about "Δ mean %". This statement is equivalent to saying that there is at least a 90.00% chance that the mean difference in optimization goal is not zero. This criterion intends to answer the question, "Is there a statistically significant difference in mean optimization goal performance?". It also means there is no more than a 10.00% chance this criterion reports a statistically significant difference when the true difference in mean optimization goal is zero -- a "false positive". We assume you are willing to accept a 10.00% chance of inaccurately detecting a change in performance when no true difference exists.

The table below, if present, lists those experiments that have experienced a statistically significant change in mean optimization goal performance between baseline and comparison SHAs with 90.00% confidence OR have been detected as newly erratic. Negative values of "Δ mean %" mean that baseline is faster, whereas positive values of "Δ mean %" mean that comparison is faster. Results that do not exhibit more than a ±5.00% change in their mean optimization goal are discarded. An experiment is erratic if its coefficient of variation is greater than 0.1. The abbreviated table will be omitted if no interesting change is observed.

No interesting changes in experiment optimization goals with confidence ≥ 90.00% and |Δ mean %| ≥ 5.00%.

Fine details of change detection per experiment.
experiment goal Δ mean % Δ mean % CI confidence
tcp_syslog_to_blackhole ingress throughput +0.52 [+0.39, +0.65] 100.00%
otel_to_otel_logs ingress throughput +0.31 [-1.28, +1.91] 25.43%
idle egress throughput +0.07 [-2.39, +2.54] 3.99%
dogstatsd_string_interner_8MiB_50k ingress throughput +0.02 [-0.03, +0.08] 57.78%
uds_dogstatsd_to_api ingress throughput +0.02 [-0.16, +0.21] 16.37%
dogstatsd_string_interner_8MiB_10k ingress throughput +0.02 [-0.02, +0.06] 54.81%
trace_agent_json ingress throughput +0.02 [-0.12, +0.15] 15.90%
dogstatsd_string_interner_128MiB_1k ingress throughput +0.01 [-0.13, +0.15] 8.61%
file_tree egress throughput +0.01 [-1.83, +1.84] 0.56%
dogstatsd_string_interner_8MiB_1k ingress throughput +0.00 [-0.09, +0.10] 3.22%
dogstatsd_string_interner_64MiB_1k ingress throughput +0.00 [-0.13, +0.13] 1.05%
dogstatsd_string_interner_64MiB_100 ingress throughput +0.00 [-0.14, +0.14] 0.54%
dogstatsd_string_interner_128MiB_100 ingress throughput +0.00 [-0.14, +0.14] 0.09%
trace_agent_msgpack ingress throughput -0.00 [-0.13, +0.13] 1.96%
dogstatsd_string_interner_8MiB_100 ingress throughput -0.01 [-0.14, +0.12] 8.29%
dogstatsd_string_interner_8MiB_100k ingress throughput -0.01 [-0.06, +0.05] 20.14%
tcp_dd_logs_filter_exclude ingress throughput -0.04 [-0.17, +0.09] 40.17%
file_to_blackhole egress throughput -0.11 [-1.12, +0.91] 13.56%

@vickenty vickenty marked this pull request as ready for review November 8, 2023 13:07
@vickenty vickenty requested review from a team as code owners November 8, 2023 13:07
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@pgimalac pgimalac left a comment

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LGTM, just a few nits

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@vickenty vickenty merged commit 4106da1 into main Nov 23, 2023
11 of 16 checks passed
@vickenty vickenty deleted the vickenty/dsd-top branch November 23, 2023 18:05
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5 participants