go package学习——runtime

package runtime主要是与go的runtime系统进行互动操作，例如控制goroutine的函数等。它也包含reflect package所需的低等级信息。

1. Environment Variables
GOGC: 设置初始的垃圾回收百分比。默认值为GOGC=100；如果设置GOGC=off，则会完全关闭垃圾回收功能。runtime/debug package的SetGCPercent函数可以在运行时改变其值。

GOGCTRACE: 从垃圾回收处控制debug输出。

GOMAXPROCS : 控制同时运行用户态go程序的操作系统线程数。

GOTRACEBACK : 控制错误导致的输出数量。

GOARCH, GOOS, GOPATH, GOROOT: 386或amd64、linux或windows、开发目录、安装目录。

Index

• Constants
• Variables
• func BlockProfile(p []BlockProfileRecord) (n int, ok bool)
• func Breakpoint()
• func CPUProfile() []byte
• func Caller(skip int) (pc uintptr, file string, line int, ok bool)
• func Callers(skip int, pc []uintptr) int
• func GC()
• func GOMAXPROCS(n int) int
• func GOROOT() string
• func Goexit()
• func GoroutineProfile(p []StackRecord) (n int, ok bool)
• func Gosched()
• func LockOSThread()
• func MemProfile(p []MemProfileRecord, inuseZero bool) (n int, ok bool)
• func NumCPU() int
• func NumCgoCall() int64
• func NumGoroutine() int
• func ReadMemStats(m *MemStats)
• func SetBlockProfileRate(rate int)
• func SetCPUProfileRate(hz int)
• func SetFinalizer(x, f interface{})
• func Stack(buf []byte, all bool) int
• func ThreadCreateProfile(p []StackRecord) (n int, ok bool)
• func UnlockOSThread()
• func Version() string
• type BlockProfileRecord
• type Error
• type Func
  • func FuncForPC(pc uintptr) *Func
  • func (f *Func) Entry() uintptr
  • func (f *Func) FileLine(pc uintptr) (file string, line int)
  • func (f *Func) Name() string
• type MemProfileRecord
  • func (r *MemProfileRecord) InUseBytes() int64
  • func (r *MemProfileRecord) InUseObjects() int64
  • func (r *MemProfileRecord) Stack() []uintptr
• type MemStats
• type StackRecord
  • func (r *StackRecord) Stack() []uintptr
• type TypeAssertionError
  • func (e *TypeAssertionError) Error() string
  • func (*TypeAssertionError) RuntimeError()

Package Files

compiler.go debug.go error.go extern.go mem.go mgc0.go softfloat64.go type.go

2. 基本函数

func GC

func GC()

运行垃圾回收。

func NumCPU

func NumCPU() int

返回本地主机的逻辑CPU数量。

func GOMAXPROCS

func GOMAXPROCS(n int) int

设置可以同时进行运算的CPU数量；如果n<1，则不改变当前设置；可以通过上面的NumCPU函数获得参数n。

func Goexit

func Goexit()

终止调用它的goroutine；其它goroutine不受影响。

func Gosched

func Gosched()

调用此函数的goroutine会主动放弃处理器，让其它goroutine使用此处理其，最初的goroutine排队等待被执行。

func NumGoroutine

func NumGoroutine() int

返回当前存在的goroutine数量。

3. type Func

type Func

type Func struct { // contains filtered or unexported fields }

func (*Func) Entry

func (f *Func) Entry() uintptr

返回函数的入口地址。

func (*Func) FileLine

func (f *Func) FileLine(pc uintptr) (file string, line int)

根据程序的入口地址pc，返回文件名及源代码行数。

func (*Func) Name

func (f *Func) Name() string

返回函数名。

4. type MemStats

type MemStats struct {
    // General statistics.
    Alloc      uint64 // bytes allocated and still in use
    TotalAlloc uint64 // bytes allocated (even if freed)
    Sys        uint64 // bytes obtained from system (should be sum of XxxSys below)
    Lookups    uint64 // number of pointer lookups
    Mallocs    uint64 // number of mallocs
    Frees      uint64 // number of frees

    // Main allocation heap statistics.
    HeapAlloc    uint64 // bytes allocated and still in use
    HeapSys      uint64 // bytes obtained from system
    HeapIdle     uint64 // bytes in idle spans
    HeapInuse    uint64 // bytes in non-idle span
    HeapReleased uint64 // bytes released to the OS
    HeapObjects  uint64 // total number of allocated objects

    // Low-level fixed-size structure allocator statistics.
    //	Inuse is bytes used now.
    //	Sys is bytes obtained from system.
    StackInuse  uint64 // bootstrap stacks
    StackSys    uint64
    MSpanInuse  uint64 // mspan structures
    MSpanSys    uint64
    MCacheInuse uint64 // mcache structures
    MCacheSys   uint64
    BuckHashSys uint64 // profiling bucket hash table

    // Garbage collector statistics.
    NextGC       uint64 // next run in HeapAlloc time (bytes)
    LastGC       uint64 // last run in absolute time (ns)
    PauseTotalNs uint64
    PauseNs      [256]uint64 // circular buffer of recent GC pause times, most recent at [(NumGC+255)%256]
    NumGC        uint32
    EnableGC     bool
    DebugGC      bool

    // Per-size allocation statistics.
    // 61 is NumSizeClasses in the C code.
    BySize [61]struct {
        Size    uint32
        Mallocs uint64
        Frees   uint64
    }
}

记录所统计的内存分配情况。