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3e24e84172
Resolves: #15433 When I converted prometheus to use slog in #14906, I update both the `QueryLogger` interface, as well as how the log calls to the `QueryLogger` were built up in `promql.Engine.exec()`. The backing logger for the `QueryLogger` in the engine is a `util/logging.JSONFileLogger`, and it's implementation of the `With()` method updates the logger the logger in place with the new keyvals added onto the underlying slog.Logger, which means they get inherited onto everything after. All subsequent calls to `With()`, even in later queries, would continue to then append on more and more keyvals for the various params and fields built up in the logger. In turn, this causes unbounded growth of the logger, leading to increased memory usage, and in at least one report was the likely cause of an OOM kill. More information can be found in the issue and the linked slack thread. This commit does a few things: - It was referenced in feedback in #14906 that it would've been better to not change the `QueryLogger` interface if possible, this PR proposes changes that bring it closer to alignment with the pre-3.0 `QueryLogger` interface contract - reverts `promql.Engine.exec()`'s usage of the query logger to the pattern of building up an array of args to pass at once to the end log call. Avoiding the repetitious calls to `.With()` are what resolve the issue with the logger growth/memory usage. - updates the scrape failure logger to use the update `QueryLogger` methods in the contract. - updates tests accordingly - cleans up unused methods Builds and passes tests successfully. Tested locally and confirmed I could no longer reproduce the issue/it resolved the issue. Signed-off-by: TJ Hoplock <t.hoplock@gmail.com>
66 lines
2 KiB
Go
66 lines
2 KiB
Go
// Copyright 2020 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 logging
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import (
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"context"
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"fmt"
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"log/slog"
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"os"
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"github.com/prometheus/common/promslog"
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)
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// JSONFileLogger represents a logger that writes JSON to a file. It implements the promql.QueryLogger interface.
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type JSONFileLogger struct {
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logger *slog.Logger
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file *os.File
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}
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// NewJSONFileLogger returns a new JSONFileLogger.
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func NewJSONFileLogger(s string) (*JSONFileLogger, error) {
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if s == "" {
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return nil, nil
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}
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f, err := os.OpenFile(s, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o666)
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if err != nil {
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return nil, fmt.Errorf("can't create json log file: %w", err)
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}
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jsonFmt := &promslog.AllowedFormat{}
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_ = jsonFmt.Set("json")
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return &JSONFileLogger{
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logger: promslog.New(&promslog.Config{Format: jsonFmt, Writer: f}),
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file: f,
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}, nil
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}
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// Close closes the underlying file. It implements the promql.QueryLogger interface.
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func (l *JSONFileLogger) Close() error {
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return l.file.Close()
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}
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// With calls the `With()` method on the underlying `log/slog.Logger` with the
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// provided msg and args. It implements the promql.QueryLogger interface.
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func (l *JSONFileLogger) With(args ...any) {
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l.logger = l.logger.With(args...)
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}
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// Log calls the `Log()` method on the underlying `log/slog.Logger` with the
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// provided msg and args. It implements the promql.QueryLogger interface.
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func (l *JSONFileLogger) Log(ctx context.Context, level slog.Level, msg string, args ...any) {
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l.logger.Log(ctx, level, msg, args...)
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}
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