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Published: Jan 21, 2013 License: BSD-3-Clause Imports: 9 Imported by: 0



Package pprof writes runtime profiling data in the format expected by the pprof visualization tool. For more information about pprof, see http://code.google.com/p/google-perftools/.



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func StartCPUProfile

func StartCPUProfile(w io.Writer) error

StartCPUProfile enables CPU profiling for the current process. While profiling, the profile will be buffered and written to w. StartCPUProfile returns an error if profiling is already enabled.

func StopCPUProfile

func StopCPUProfile()

StopCPUProfile stops the current CPU profile, if any. StopCPUProfile only returns after all the writes for the profile have completed.

func WriteHeapProfile

func WriteHeapProfile(w io.Writer) error

WriteHeapProfile is shorthand for Lookup("heap").WriteTo(w, 0). It is preserved for backwards compatibility.


type Profile

type Profile struct {
	// contains filtered or unexported fields

A Profile is a collection of stack traces showing the call sequences that led to instances of a particular event, such as allocation. Packages can create and maintain their own profiles; the most common use is for tracking resources that must be explicitly closed, such as files or network connections.

A Profile's methods can be called from multiple goroutines simultaneously.

Each Profile has a unique name. A few profiles are predefined:

goroutine    - stack traces of all current goroutines
heap         - a sampling of all heap allocations
threadcreate - stack traces that led to the creation of new OS threads
block        - stack traces that led to blocking on synchronization primitives

These predefined profiles maintain themselves and panic on an explicit Add or Remove method call.

The CPU profile is not available as a Profile. It has a special API, the StartCPUProfile and StopCPUProfile functions, because it streams output to a writer during profiling.

func Lookup

func Lookup(name string) *Profile

Lookup returns the profile with the given name, or nil if no such profile exists.

func NewProfile

func NewProfile(name string) *Profile

NewProfile creates a new profile with the given name. If a profile with that name already exists, NewProfile panics. The convention is to use a 'import/path.' prefix to create separate name spaces for each package.

func Profiles

func Profiles() []*Profile

Profiles returns a slice of all the known profiles, sorted by name.

func (*Profile) Add

func (p *Profile) Add(value interface{}, skip int)

Add adds the current execution stack to the profile, associated with value. Add stores value in an internal map, so value must be suitable for use as a map key and will not be garbage collected until the corresponding call to Remove. Add panics if the profile already contains a stack for value.

The skip parameter has the same meaning as runtime.Caller's skip and controls where the stack trace begins. Passing skip=0 begins the trace in the function calling Add. For example, given this execution stack:

called from rpc.NewClient
called from mypkg.Run
called from main.main

Passing skip=0 begins the stack trace at the call to Add inside rpc.NewClient. Passing skip=1 begins the stack trace at the call to NewClient inside mypkg.Run.

func (*Profile) Count

func (p *Profile) Count() int

Count returns the number of execution stacks currently in the profile.

func (*Profile) Name

func (p *Profile) Name() string

Name returns this profile's name, which can be passed to Lookup to reobtain the profile.

func (*Profile) Remove

func (p *Profile) Remove(value interface{})

Remove removes the execution stack associated with value from the profile. It is a no-op if the value is not in the profile.

func (*Profile) WriteTo

func (p *Profile) WriteTo(w io.Writer, debug int) error

WriteTo writes a pprof-formatted snapshot of the profile to w. If a write to w returns an error, WriteTo returns that error. Otherwise, WriteTo returns nil.

The debug parameter enables additional output. Passing debug=0 prints only the hexadecimal addresses that pprof needs. Passing debug=1 adds comments translating addresses to function names and line numbers, so that a programmer can read the profile without tools.

The predefined profiles may assign meaning to other debug values; for example, when printing the "goroutine" profile, debug=2 means to print the goroutine stacks in the same form that a Go program uses when dying due to an unrecovered panic.



  • A bug in the OS X Snow Leopard 64-bit kernel prevents CPU profiling from giving accurate results on that system.

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