70 lines
3.6 KiB
Go
70 lines
3.6 KiB
Go
// Copyright 2021 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 collectors
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import "github.com/prometheus/client_golang/prometheus"
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// NewGoCollector returns a collector that exports metrics about the current Go
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// process. This includes memory stats. To collect those, runtime.ReadMemStats
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// is called. This requires to “stop the world”, which usually only happens for
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// garbage collection (GC). Take the following implications into account when
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// deciding whether to use the Go collector:
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//
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// 1. The performance impact of stopping the world is the more relevant the more
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// frequently metrics are collected. However, with Go1.9 or later the
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// stop-the-world time per metrics collection is very short (~25µs) so that the
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// performance impact will only matter in rare cases. However, with older Go
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// versions, the stop-the-world duration depends on the heap size and can be
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// quite significant (~1.7 ms/GiB as per
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// https://go-review.googlesource.com/c/go/+/34937).
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//
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// 2. During an ongoing GC, nothing else can stop the world. Therefore, if the
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// metrics collection happens to coincide with GC, it will only complete after
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// GC has finished. Usually, GC is fast enough to not cause problems. However,
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// with a very large heap, GC might take multiple seconds, which is enough to
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// cause scrape timeouts in common setups. To avoid this problem, the Go
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// collector will use the memstats from a previous collection if
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// runtime.ReadMemStats takes more than 1s. However, if there are no previously
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// collected memstats, or their collection is more than 5m ago, the collection
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// will block until runtime.ReadMemStats succeeds.
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//
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// NOTE: The problem is solved in Go 1.15, see
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// https://github.com/golang/go/issues/19812 for the related Go issue.
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func NewGoCollector() prometheus.Collector {
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//nolint:staticcheck // Ignore SA1019 until v2.
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return prometheus.NewGoCollector()
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}
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// NewBuildInfoCollector returns a collector collecting a single metric
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// "go_build_info" with the constant value 1 and three labels "path", "version",
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// and "checksum". Their label values contain the main module path, version, and
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// checksum, respectively. The labels will only have meaningful values if the
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// binary is built with Go module support and from source code retrieved from
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// the source repository (rather than the local file system). This is usually
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// accomplished by building from outside of GOPATH, specifying the full address
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// of the main package, e.g. "GO111MODULE=on go run
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// github.com/prometheus/client_golang/examples/random". If built without Go
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// module support, all label values will be "unknown". If built with Go module
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// support but using the source code from the local file system, the "path" will
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// be set appropriately, but "checksum" will be empty and "version" will be
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// "(devel)".
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//
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// This collector uses only the build information for the main module. See
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// https://github.com/povilasv/prommod for an example of a collector for the
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// module dependencies.
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func NewBuildInfoCollector() prometheus.Collector {
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//nolint:staticcheck // Ignore SA1019 until v2.
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return prometheus.NewBuildInfoCollector()
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}
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