mirror of
https://github.com/dutchcoders/transfer.sh.git
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116 lines
3.4 KiB
Go
116 lines
3.4 KiB
Go
// Copyright 2018 Google LLC
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//
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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 profiler
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import (
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"bytes"
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"context"
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"fmt"
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"runtime"
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"time"
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"github.com/google/pprof/profile"
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)
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// heapProfile collects an in-use heap profile. The heap profiles returned by
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// the runtime also include the heap allocation metrics. We zero those out
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// since all allocations since program start are recorded, so these make the
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// profile large and there is a separate alloc profile type which shows
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// allocations from a set duration.
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func heapProfile(prof *bytes.Buffer) error {
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p, err := goHeapProfile()
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if err != nil {
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return err
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}
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for _, s := range p.Sample {
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s.Value[0] = 0
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s.Value[1] = 0
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}
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// Merge profile with itself to remove samples with only zero values and
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// reduce profile size.
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p, err = profile.Merge([]*profile.Profile{p})
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if err != nil {
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return err
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}
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return p.Write(prof)
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}
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// deltaAllocProfile collects an allocation profile by gathering a heap profile,
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// sleeping for the specified duration, gathering another heap profile and
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// subtracting the initial one from that. It then drops the in-use metrics from
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// the profile. If requested, it forces the GC before taking each of the heap
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// profiles, which improves the profile accuracy (see docs in
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// https://golang.org/src/runtime/mprof.go on why).
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func deltaAllocProfile(ctx context.Context, duration time.Duration, forceGC bool, prof *bytes.Buffer) error {
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p1, err := allocProfile(forceGC)
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if err != nil {
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return err
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}
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sleep(ctx, duration)
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p2, err := allocProfile(forceGC)
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if err != nil {
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return err
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}
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p1.Scale(-1)
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p, err := profile.Merge([]*profile.Profile{p1, p2})
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if err != nil {
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return err
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}
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p.DurationNanos = duration.Nanoseconds()
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return p.Write(prof)
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}
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// allocProfile collects a single heap profile, and removes all metrics but
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// allocation metrics.
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func allocProfile(forceGC bool) (*profile.Profile, error) {
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if forceGC {
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runtime.GC()
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}
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p, err := goHeapProfile()
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if err != nil {
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return nil, err
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}
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p.SampleType = p.SampleType[:2]
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for _, s := range p.Sample {
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s.Value = s.Value[:2]
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}
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return p, nil
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}
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// goHeapProfile collects a heap profile. It returns an error if the metrics
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// in the collected heap profile do not match the expected metrics.
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func goHeapProfile() (*profile.Profile, error) {
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var prof bytes.Buffer
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if err := writeHeapProfile(&prof); err != nil {
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return nil, fmt.Errorf("failed to write heap profile: %v", err)
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}
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p, err := profile.Parse(&prof)
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if err != nil {
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return nil, err
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}
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if got := len(p.SampleType); got != 4 {
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return nil, fmt.Errorf("invalid heap profile: got %d sample types, want 4", got)
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}
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for i, want := range []string{"alloc_objects", "alloc_space", "inuse_objects", "inuse_space"} {
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if got := p.SampleType[i].Type; got != want {
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return nil, fmt.Errorf("invalid heap profile: got %q sample type at index %d, want %q", got, i, want)
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}
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}
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return p, nil
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}
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