profile_test.go

Documentation: go.starlark.net/starlark

     1  // Copyright 2019 The Bazel 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  package starlark_test
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"io/ioutil"
    11  	"os"
    12  	"os/exec"
    13  	"strings"
    14  	"testing"
    15  
    16  	"go.starlark.net/starlark"
    17  )
    18  
    19  // TestProfile is a simple integration test that the profiler
    20  // emits minimally plausible pprof-compatible output.
    21  func TestProfile(t *testing.T) {
    22  	prof, err := ioutil.TempFile("", "profile_test")
    23  	if err != nil {
    24  		t.Fatal(err)
    25  	}
    26  	defer prof.Close()
    27  	defer os.Remove(prof.Name())
    28  	if err := starlark.StartProfile(prof); err != nil {
    29  		t.Fatal(err)
    30  	}
    31  
    32  	const src = `
    33  def fibonacci(n):
    34  	x, y = 1, 1
    35  	for i in range(n):
    36  		x, y = y, x+y
    37  	return y
    38  
    39  fibonacci(100000)
    40  `
    41  
    42  	thread := new(starlark.Thread)
    43  	if _, err := starlark.ExecFile(thread, "foo.star", src, nil); err != nil {
    44  		_ = starlark.StopProfile()
    45  		t.Fatal(err)
    46  	}
    47  	if err := starlark.StopProfile(); err != nil {
    48  		t.Fatal(err)
    49  	}
    50  	prof.Sync()
    51  	cmd := exec.Command("go", "tool", "pprof", "-top", prof.Name())
    52  	cmd.Stderr = new(bytes.Buffer)
    53  	cmd.Stdout = new(bytes.Buffer)
    54  	if err := cmd.Run(); err != nil {
    55  		t.Fatalf("pprof failed: %v; output=<<%s>>", err, cmd.Stderr)
    56  	}
    57  
    58  	// Typical output (may vary by go release):
    59  	//
    60  	// Type: wall
    61  	// Time: Apr 4, 2019 at 11:10am (EDT)
    62  	// Duration: 251.62ms, Total samples = 250ms (99.36%)
    63  	// Showing nodes accounting for 250ms, 100% of 250ms total
    64  	//  flat  flat%   sum%        cum   cum%
    65  	// 320ms   100%   100%      320ms   100%  fibonacci
    66  	//     0     0%   100%      320ms   100%  foo.star
    67  	//
    68  	// We'll assert a few key substrings are present.
    69  	got := fmt.Sprint(cmd.Stdout)
    70  	for _, want := range []string{
    71  		"flat%",
    72  		"fibonacci",
    73  		"foo.star",
    74  	} {
    75  		if !strings.Contains(got, want) {
    76  			t.Errorf("output did not contain %q", want)
    77  		}
    78  	}
    79  	if t.Failed() {
    80  		t.Logf("stderr=%v", cmd.Stderr)
    81  		t.Logf("stdout=%v", cmd.Stdout)
    82  	}
    83  }
    84
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