trace_unix_test.go

     1  // Copyright 2017 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
     6  
     7  package main
     8  
     9  import (
    10  	"bytes"
    11  	"cmd/internal/traceviewer"
    12  	traceparser "internal/trace"
    13  	"io"
    14  	"runtime"
    15  	"runtime/trace"
    16  	"sync"
    17  	"syscall"
    18  	"testing"
    19  	"time"
    20  )
    21  
    22  // TestGoroutineInSyscall tests threads for timer goroutines
    23  // that preexisted when the tracing started were not counted
    24  // as threads in syscall. See golang.org/issues/22574.
    25  func TestGoroutineInSyscall(t *testing.T) {
    26  	// Start one goroutine blocked in syscall.
    27  	//
    28  	// TODO: syscall.Pipe used to cause the goroutine to
    29  	// remain blocked in syscall is not portable. Replace
    30  	// it with a more portable way so this test can run
    31  	// on non-unix architecture e.g. Windows.
    32  	var p [2]int
    33  	if err := syscall.Pipe(p[:]); err != nil {
    34  		t.Fatalf("failed to create pipe: %v", err)
    35  	}
    36  
    37  	var wg sync.WaitGroup
    38  	defer func() {
    39  		syscall.Write(p[1], []byte("a"))
    40  		wg.Wait()
    41  
    42  		syscall.Close(p[0])
    43  		syscall.Close(p[1])
    44  	}()
    45  	wg.Add(1)
    46  	go func() {
    47  		var tmp [1]byte
    48  		syscall.Read(p[0], tmp[:])
    49  		wg.Done()
    50  	}()
    51  
    52  	// Start multiple timer goroutines.
    53  	allTimers := make([]*time.Timer, 2*runtime.GOMAXPROCS(0))
    54  	defer func() {
    55  		for _, timer := range allTimers {
    56  			timer.Stop()
    57  		}
    58  	}()
    59  
    60  	var timerSetup sync.WaitGroup
    61  	for i := range allTimers {
    62  		timerSetup.Add(1)
    63  		go func(i int) {
    64  			defer timerSetup.Done()
    65  			allTimers[i] = time.AfterFunc(time.Hour, nil)
    66  		}(i)
    67  	}
    68  	timerSetup.Wait()
    69  
    70  	// Collect and parse trace.
    71  	buf := new(bytes.Buffer)
    72  	if err := trace.Start(buf); err != nil {
    73  		t.Fatalf("failed to start tracing: %v", err)
    74  	}
    75  	trace.Stop()
    76  
    77  	res, err := traceparser.Parse(buf, "")
    78  	if err == traceparser.ErrTimeOrder {
    79  		t.Skipf("skipping due to golang.org/issue/16755 (timestamps are unreliable): %v", err)
    80  	} else if err != nil {
    81  		t.Fatalf("failed to parse trace: %v", err)
    82  	}
    83  
    84  	// Check only one thread for the pipe read goroutine is
    85  	// considered in-syscall.
    86  	c := viewerDataTraceConsumer(io.Discard, 0, 1<<63-1)
    87  	c.consumeViewerEvent = func(ev *traceviewer.Event, _ bool) {
    88  		if ev.Name == "Threads" {
    89  			arg := ev.Arg.(*threadCountersArg)
    90  			if arg.InSyscall > 1 {
    91  				t.Errorf("%d threads in syscall at time %v; want less than 1 thread in syscall", arg.InSyscall, ev.Time)
    92  			}
    93  		}
    94  	}
    95  
    96  	param := &traceParams{
    97  		parsed:  res,
    98  		endTime: int64(1<<63 - 1),
    99  	}
   100  	if err := generateTrace(param, c); err != nil {
   101  		t.Fatalf("failed to generate ViewerData: %v", err)
   102  	}
   103  }
   104
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