github.com/euank/go@v0.0.0-20160829210321-495514729181/src/runtime/trace/trace.go (about)

     1  // Copyright 2015 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 execution tracer.
     6  // The tracer captures a wide range of execution events like goroutine
     7  // creation/blocking/unblocking, syscall enter/exit/block, GC-related events,
     8  // changes of heap size, processor start/stop, etc and writes them to an io.Writer
     9  // in a compact form. A precise nanosecond-precision timestamp and a stack
    10  // trace is captured for most events. A trace can be analyzed later with
    11  // 'go tool trace' command.
    12  package trace
    13  
    14  import (
    15  	"io"
    16  	"runtime"
    17  )
    18  
    19  // Start enables tracing for the current program.
    20  // While tracing, the trace will be buffered and written to w.
    21  // Start returns an error if tracing is already enabled.
    22  func Start(w io.Writer) error {
    23  	if err := runtime.StartTrace(); err != nil {
    24  		return err
    25  	}
    26  	go func() {
    27  		for {
    28  			data := runtime.ReadTrace()
    29  			if data == nil {
    30  				break
    31  			}
    32  			w.Write(data)
    33  		}
    34  	}()
    35  	return nil
    36  }
    37  
    38  // Stop stops the current tracing, if any.
    39  // Stop only returns after all the writes for the trace have completed.
    40  func Stop() {
    41  	runtime.StopTrace()
    42  }