90 lines
1.8 KiB
Go
90 lines
1.8 KiB
Go
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// Copyright 2022 The Go 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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//go:build !plan9 && !windows
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package main
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// Make many C-to-Go callback while collecting a CPU profile.
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//
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// This is a regression test for issue 50936.
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/*
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#include <unistd.h>
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void goCallbackPprof();
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static void callGo() {
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// Spent >20us in C so this thread is eligible for sysmon to retake its
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// P.
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usleep(50);
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goCallbackPprof();
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}
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*/
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import "C"
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import (
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"fmt"
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"os"
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"runtime/pprof"
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"runtime"
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"time"
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)
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func init() {
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register("CgoPprofCallback", CgoPprofCallback)
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}
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//export goCallbackPprof
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func goCallbackPprof() {
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// No-op. We want to stress the cgocall and cgocallback internals,
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// landing as many pprof signals there as possible.
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}
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func CgoPprofCallback() {
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// Issue 50936 was a crash in the SIGPROF handler when the signal
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// arrived during the exitsyscall following a cgocall(back) in dropg or
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// execute, when updating mp.curg.
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//
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// These are reachable only when exitsyscall finds no P available. Thus
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// we make C calls from significantly more Gs than there are available
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// Ps. Lots of runnable work combined with >20us spent in callGo makes
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// it possible for sysmon to retake Ps, forcing C calls to go down the
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// desired exitsyscall path.
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//
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// High GOMAXPROCS is used to increase opportunities for failure on
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// high CPU machines.
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const (
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P = 16
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G = 64
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)
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runtime.GOMAXPROCS(P)
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f, err := os.CreateTemp("", "prof")
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(2)
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}
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defer f.Close()
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if err := pprof.StartCPUProfile(f); err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(2)
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}
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for i := 0; i < G; i++ {
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go func() {
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for {
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C.callGo()
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}
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}()
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}
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time.Sleep(time.Second)
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pprof.StopCPUProfile()
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fmt.Println("OK")
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}
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