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feat(fix-update): allow user to profile commands with pprof (bazel-co…
…ntrib#1685) This adds two flags to the `fix` and the `update` command, `-cpuprofile` and `-memprofile`, which allow users to create output CPU and memory `pprof` files to better understand the performance of Gazelle. This is very helpful in debugging issues like bazel-contrib#1688, which show up in certain repository setups. The implementation mostly followed the instructions on https://pkg.go.dev/runtime/pprof#hdr-Profiling_a_Go_program to set up profiling options for the command in the `cmd/gazelle`. Tests were added to ensure that the `newProfile` would return a `profile{}` that wouldn't panic, even if either provider is empty. Co-authored-by: Fabian Meumertzheim <fabian@meumertzhe.im>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,53 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "os" | ||
| "runtime" | ||
| "runtime/pprof" | ||
| ) | ||
|
|
||
| type profiler struct { | ||
| cpuProfile *os.File | ||
| memProfile string | ||
| } | ||
|
|
||
| // newProfiler creates a profiler that writes to the given files. | ||
| // it returns an empty profiler if both files are empty. | ||
| // so that stop() will never fail. | ||
| func newProfiler(cpuProfile, memProfile string) (profiler, error) { | ||
| if cpuProfile == "" { | ||
| return profiler{ | ||
| memProfile: memProfile, | ||
| }, nil | ||
| } | ||
|
|
||
| f, err := os.Create(cpuProfile) | ||
| if err != nil { | ||
| return profiler{}, err | ||
| } | ||
| pprof.StartCPUProfile(f) | ||
|
|
||
| return profiler{ | ||
| cpuProfile: f, | ||
| memProfile: memProfile, | ||
| }, nil | ||
| } | ||
|
|
||
| func (p *profiler) stop() error { | ||
| if p.cpuProfile != nil { | ||
| pprof.StopCPUProfile() | ||
| p.cpuProfile.Close() | ||
| } | ||
|
|
||
| if p.memProfile == "" { | ||
| return nil | ||
| } | ||
|
|
||
| f, err := os.Create(p.memProfile) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer f.Close() | ||
| runtime.GC() | ||
| return pprof.WriteHeapProfile(f) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,73 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "os" | ||
| "path/filepath" | ||
| "testing" | ||
| ) | ||
|
|
||
| func TestEmptyProfiler(t *testing.T) { | ||
| dir := t.TempDir() | ||
| tests := []struct { | ||
| name string | ||
| cpuProfile string | ||
| memProfile string | ||
| }{ | ||
| { | ||
| name: "cpuProfile", | ||
| cpuProfile: filepath.Join(dir, "cpu.prof"), | ||
| }, | ||
| { | ||
| name: "memProfile", | ||
| memProfile: filepath.Join(dir, "mem.prof"), | ||
| }, | ||
| { | ||
| name: "empty", | ||
| }, | ||
| } | ||
|
|
||
| for _, test := range tests { | ||
| t.Run("", func(t *testing.T) { | ||
| p, err := newProfiler(test.cpuProfile, test.memProfile) | ||
| if err != nil { | ||
| t.Fatalf("newProfiler failed: %v", err) | ||
| } | ||
| if err := p.stop(); err != nil { | ||
| t.Fatalf("stop failed: %v", err) | ||
| } | ||
| }) | ||
| } | ||
| } | ||
|
|
||
| func TestProfiler(t *testing.T) { | ||
| dir := t.TempDir() | ||
| cpuProfileName := filepath.Join(dir, "cpu.prof") | ||
| memProfileName := filepath.Join(dir, "mem.prof") | ||
| t.Cleanup(func() { | ||
| os.Remove(cpuProfileName) | ||
| os.Remove(memProfileName) | ||
| }) | ||
|
|
||
| p, err := newProfiler(cpuProfileName, memProfileName) | ||
| if err != nil { | ||
| t.Fatalf("newProfiler failed: %v", err) | ||
| } | ||
| if p.cpuProfile == nil { | ||
| t.Fatal("Expected cpuProfile to be non-nil") | ||
| } | ||
| if p.memProfile != memProfileName { | ||
| t.Fatalf("Expected memProfile to be %s, got %s", memProfileName, p.memProfile) | ||
| } | ||
|
|
||
| if err := p.stop(); err != nil { | ||
| t.Fatalf("stop failed: %v", err) | ||
| } | ||
|
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| if _, err := os.Stat(cpuProfileName); os.IsNotExist(err) { | ||
| t.Fatalf("CPU profile file %s was not created", cpuProfileName) | ||
| } | ||
|
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||
| if _, err := os.Stat(memProfileName); os.IsNotExist(err) { | ||
| t.Fatalf("Memory profile file %s was not created", memProfileName) | ||
| } | ||
| } |
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