profiling.go

Documentation: k8s.io/kubectl/pkg/cmd

     1  /*
     2  Copyright 2017 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package cmd
    18  
    19  import (
    20  	"fmt"
    21  	"os"
    22  	"os/signal"
    23  	"runtime"
    24  	"runtime/pprof"
    25  
    26  	"github.com/spf13/pflag"
    27  )
    28  
    29  var (
    30  	profileName   string
    31  	profileOutput string
    32  )
    33  
    34  func addProfilingFlags(flags *pflag.FlagSet) {
    35  	flags.StringVar(&profileName, "profile", "none", "Name of profile to capture. One of (none|cpu|heap|goroutine|threadcreate|block|mutex)")
    36  	flags.StringVar(&profileOutput, "profile-output", "profile.pprof", "Name of the file to write the profile to")
    37  }
    38  
    39  func initProfiling() error {
    40  	var (
    41  		f   *os.File
    42  		err error
    43  	)
    44  	switch profileName {
    45  	case "none":
    46  		return nil
    47  	case "cpu":
    48  		f, err = os.Create(profileOutput)
    49  		if err != nil {
    50  			return err
    51  		}
    52  		err = pprof.StartCPUProfile(f)
    53  		if err != nil {
    54  			return err
    55  		}
    56  	// Block and mutex profiles need a call to Set{Block,Mutex}ProfileRate to
    57  	// output anything. We choose to sample all events.
    58  	case "block":
    59  		runtime.SetBlockProfileRate(1)
    60  	case "mutex":
    61  		runtime.SetMutexProfileFraction(1)
    62  	default:
    63  		// Check the profile name is valid.
    64  		if profile := pprof.Lookup(profileName); profile == nil {
    65  			return fmt.Errorf("unknown profile '%s'", profileName)
    66  		}
    67  	}
    68  
    69  	// If the command is interrupted before the end (ctrl-c), flush the
    70  	// profiling files
    71  	c := make(chan os.Signal, 1)
    72  	signal.Notify(c, os.Interrupt)
    73  	go func() {
    74  		<-c
    75  		f.Close()
    76  		flushProfiling()
    77  		os.Exit(0)
    78  	}()
    79  
    80  	return nil
    81  }
    82  
    83  func flushProfiling() error {
    84  	switch profileName {
    85  	case "none":
    86  		return nil
    87  	case "cpu":
    88  		pprof.StopCPUProfile()
    89  	case "heap":
    90  		runtime.GC()
    91  		fallthrough
    92  	default:
    93  		profile := pprof.Lookup(profileName)
    94  		if profile == nil {
    95  			return nil
    96  		}
    97  		f, err := os.Create(profileOutput)
    98  		if err != nil {
    99  			return err
   100  		}
   101  		defer f.Close()
   102  		profile.WriteTo(f, 0)
   103  	}
   104  
   105  	return nil
   106  }
   107
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