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https://github.com/prometheus/prometheus.git
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86 lines
3 KiB
Go
86 lines
3 KiB
Go
// Copyright The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tsdb
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import (
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"context"
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"strconv"
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"testing"
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"time"
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"github.com/stretchr/testify/require"
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"github.com/prometheus/prometheus/model/labels"
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"github.com/prometheus/prometheus/tsdb/wlog"
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)
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// BenchmarkLabelValues_SlowPath benchmarks the performance of LabelValues when the matcher
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// is far ahead of the candidate posting list. This reproduces the performance regression
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// described in #14551 where dense candidates caused O(N) iteration instead of O(log N) seeking.
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func BenchmarkLabelValues_SlowPath(b *testing.B) {
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// Create a head with some data.
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opts := DefaultHeadOptions()
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opts.ChunkDirRoot = b.TempDir()
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h, err := NewHead(nil, nil, nil, nil, opts, nil)
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require.NoError(b, err)
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defer h.Close()
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app := h.Appender(context.Background())
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// 1. Create a large number of series for a "candidate" label (e.g. "job").
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// We want these to NOT match the target matcher, but be candidates for a different label.
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// We use "job=api" and "instance=..."
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// We want the interaction to be:
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// LabelValues("instance", "job"="api")
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// "job"="api" will have 1 series at the END.
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// "instance" will have 100k series.
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// Actually, let's stick to the reproduction case:
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// distinct values for "val1".
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// "b"="1" matcher.
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// Create 100k series with the same label value ("common") but without the matcher label.
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// This results in a single large posting list for that value, simulating a dense candidate.
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for i := range 100000 {
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_, err := app.Append(0, labels.FromStrings("val1", "common", "extra", strconv.Itoa(i)), time.Now().UnixMilli(), 1)
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require.NoError(b, err)
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}
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// Create 1 series that matches the label "b=1", with a series ID greater than all previous ones.
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// This forces the intersection to skip over all 100k previous candidates.
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_, err = app.Append(0, labels.FromStrings("val1", "common", "b", "1"), time.Now().UnixMilli(), 1)
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require.NoError(b, err)
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require.NoError(b, app.Commit())
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ctx := context.Background()
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matcher := labels.MustNewMatcher(labels.MatchEqual, "b", "1")
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// Use the correct method to access label values.
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idx, err := h.Index()
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require.NoError(b, err)
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b.ResetTimer()
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b.ReportAllocs()
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for b.Loop() {
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// "val1"="common" has 100k+1 postings.
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// "b=1" has 1 posting (the last one).
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vals, err := idx.LabelValues(ctx, "val1", nil, matcher)
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require.NoError(b, err)
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require.Equal(b, []string{"common"}, vals)
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}
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}
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// Ensure wlog/wal needed for NewHead.
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var _ = wlog.WL{}
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