AGNTLOG-2 - reduce payload memory usage in the logs pipeline#35351
AGNTLOG-2 - reduce payload memory usage in the logs pipeline#35351dd-mergequeue[bot] merged 1 commit intomainfrom
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Decision |
Test changes on VMUse this command from test-infra-definitions to manually test this PR changes on a VM: dda inv aws.create-vm --pipeline-id=59624210 --os-family=ubuntuNote: This applies to commit 530586f |
Static quality checks ✅Please find below the results from static quality gates Successful checksInfo
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Regression DetectorRegression Detector ResultsMetrics dashboard Baseline: 7e6f897 Optimization Goals: ✅ No significant changes detected
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| perf | experiment | goal | Δ mean % | Δ mean % CI | trials | links |
|---|---|---|---|---|---|---|
| ➖ | uds_dogstatsd_to_api_cpu | % cpu utilization | +0.87 | [+0.06, +1.68] | 1 | Logs |
| ➖ | file_to_blackhole_1000ms_latency | egress throughput | +0.08 | [-0.69, +0.86] | 1 | Logs |
| ➖ | quality_gate_logs | % cpu utilization | +0.06 | [-2.71, +2.83] | 1 | Logs |
| ➖ | file_to_blackhole_100ms_latency | egress throughput | +0.02 | [-0.66, +0.69] | 1 | Logs |
| ➖ | file_to_blackhole_0ms_latency_http1 | egress throughput | +0.01 | [-0.79, +0.82] | 1 | Logs |
| ➖ | tcp_dd_logs_filter_exclude | ingress throughput | -0.00 | [-0.03, +0.02] | 1 | Logs |
| ➖ | file_to_blackhole_0ms_latency | egress throughput | -0.01 | [-0.81, +0.79] | 1 | Logs |
| ➖ | file_to_blackhole_300ms_latency | egress throughput | -0.01 | [-0.64, +0.62] | 1 | Logs |
| ➖ | uds_dogstatsd_to_api | ingress throughput | -0.01 | [-0.30, +0.28] | 1 | Logs |
| ➖ | file_to_blackhole_0ms_latency_http2 | egress throughput | -0.02 | [-0.79, +0.76] | 1 | Logs |
| ➖ | file_tree | memory utilization | -0.05 | [-0.18, +0.09] | 1 | Logs |
| ➖ | file_to_blackhole_1000ms_latency_linear_load | egress throughput | -0.05 | [-0.51, +0.41] | 1 | Logs |
| ➖ | file_to_blackhole_500ms_latency | egress throughput | -0.09 | [-0.87, +0.69] | 1 | Logs |
| ➖ | uds_dogstatsd_20mb_12k_contexts_20_senders | memory utilization | -0.28 | [-0.34, -0.22] | 1 | Logs |
| ➖ | quality_gate_idle | memory utilization | -0.87 | [-0.95, -0.78] | 1 | Logs bounds checks dashboard |
| ➖ | quality_gate_idle_all_features | memory utilization | -1.63 | [-1.75, -1.50] | 1 | Logs bounds checks dashboard |
| ➖ | tcp_syslog_to_blackhole | ingress throughput | -2.62 | [-2.67, -2.56] | 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:
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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".
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_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_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_logs, bounds check intake_connections: 10/10 replicas passed. Gate passed.
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Static quality checks ❌Please find below the results from static quality gates Error
Gate failure full details
Successful checksInfo
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| func NewPayload(messages []*Message, encoded []byte, encoding string, unencodedSize int) *Payload { | ||
| messageMetas := make([]*MessageMetadata, len(messages)) | ||
| for i, m := range messages { | ||
| // Split the metadata from the message content to avoid holding the entire message in memory |
| message := NewMessage(content, nil, "", 2) | ||
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| // Set up finalizer to track when content is GC'd | ||
| runtime.SetFinalizer(&message.content, trackGC) |
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This is a cool test.
This seems like a nice way to assert memory behaviors in unit tests and possibly prevent memory regressions in the future 👍
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/merge |
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What does this PR do?
The logs payload entity stores metadata for all of the respective messages batched within, but also stores the message contents themselves. This isn't required, all consumers of the logs payload will interact with the encoded bytes buffer rather than the raw contents. Additionally, dropping these message contents on payload construction can save considerable amounts of RSS memory for log agents experiencing enough load to buffer multiple payloads.
This PR shallow copies the message metadata into each payload, rather than injecting the whole message entity.
Motivation
Describe how you validated your changes
Validation was completed by a combination of 1. unit test additions, 2. successful code compilation, 3. SMP performance runs
Possible Drawbacks / Trade-offs
Adding memory allocation in the critical path (for the metadata shallow copy) isn't ideal, but given we're already allocating a new array for the entirety of the contents in the same code path its impact shouldn't be noticeable.
Additional Notes
The memory savings for a system under heavy load is extreme. Attached is the memory comparison used in the file_to_blackhole_1000ms_latency_linear_load regression test:
