73 lines
2.0 KiB
Go
73 lines
2.0 KiB
Go
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// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package testy
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import (
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"bytes"
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"runtime"
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"runtime/pprof"
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"testing"
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"time"
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"github.com/google/go-cmp/cmp"
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)
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type ResourceCheck struct {
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startNumRoutines int
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startDump string
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}
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func NewResourceCheck() *ResourceCheck {
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// NOTE(apenwarr): I'd rather not pre-generate a goroutine dump here.
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// However, it turns out to be tricky to debug when eg. the initial
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// goroutine count > the ending goroutine count, because of course
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// the missing ones are not in the final dump. Also, we have to
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// render the profile as a string right away, because the
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// pprof.Profile object doesn't stay stable over time. Every time
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// you render the string, you might get a different answer.
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r := &ResourceCheck{}
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r.startNumRoutines, r.startDump = goroutineDump()
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return r
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}
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func goroutineDump() (int, string) {
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p := pprof.Lookup("goroutine")
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b := &bytes.Buffer{}
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p.WriteTo(b, 1)
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return p.Count(), b.String()
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}
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func (r *ResourceCheck) Assert(t *testing.T) {
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t.Helper()
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want := r.startNumRoutines
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// Some goroutines might be still exiting, so give them a chance
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got := runtime.NumGoroutine()
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if want != got {
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_, dump := goroutineDump()
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for i := 0; i < 100; i++ {
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got = runtime.NumGoroutine()
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if want == got {
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break
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}
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time.Sleep(1 * time.Millisecond)
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}
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// If the count is *still* wrong, that's a failure.
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if want != got {
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t.Logf("goroutine diff:\n%v\n", cmp.Diff(r.startDump, dump))
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t.Logf("goroutine count: expected %d, got %d\n", want, got)
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// Don't fail if there are *fewer* goroutines than
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// expected. That just might be some leftover ones
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// from the previous test, which are pretty hard to
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// eliminate.
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if want < got {
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t.Fatalf("goroutine count: expected %d, got %d\n", want, got)
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}
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}
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}
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t.Logf("Assert: goroutines before=%d after=%d - ok\n", got, want)
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}
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