nil slice 的长度len和容量cap都是0 empty slice的长度是0, 容量是由指向底层数组决定 empty slice != nil nil slice的pointer 是nil, empty slice的pointer是底层数组的地址 slice的底层表示形式 [pointer] [length] [capacity] nil slice: [nil][0][0] empty slice: [addr][0][0] // pointer是底层数...
nil slice值是nil,nil slice切分之后的结果也是一个nil slice non-nil slice和empty slice的值不是一个nil,empty slice切分之后的结果是一个非nil的slice 引用: nil slices vs non-nil slices vs empty slices in Go language.
fmt.Println(a)//Just like 1D arrays, you don't need to initialize all the elements in a multi-dimensional array.//Un-initialized array elements will be assigned the zero value of the array type.b := [3][4]float64{ {1,3}, {4.5, -3,7.4,2}, {6,2,11}, } 二、切片初始化方式...
比如spanClass=4(或5)的mspan,它对应的sizeClass=2,它每次分配都是固定16B的大小。 初始化时,mspan数组alloc的每个元素都指向一个空的mspan:emptymspan,它不包含任何有用内存,尝试从它分配对象会直接失败。 varemptymspanmspan mcache中还有一个tiny结构,专门用于tiny类型的对象的分配,它总共16个字节。当分配tiny对...
}// Initialize the rest of the allocator.mheap_.init(spansStart, spansSize) _g_ := getg() _g_.m.mcache = allocmcache() } 上面对代码做了简单的注释,下面详细解说其中的部分功能函数。 3.1 arena 相关 arena 相关地址的大小初始化代码如下。
=""{releasem(mp)return}releasem(mp)mp=nil// 并行清扫上一轮GC未清扫的span// Pick up the remaining unswept/not being swept spans concurrently/// This shouldn't happen if we're being invoked in background// mode since proportional sweep should have just finished// sweeping everything, but...
funcmakemap(t*maptype,hint int,h*hmap)*hmap{mem,overflow:=math.MulUintptr(uintptr(hint),t.bucket.size)ifoverflow||mem>maxAlloc{hint=0}// initialize Hmapifh==nil{h=new(hmap)}h.hash0=fastrand()// Find the size parameter B which will hold the requested # of elements.// For hint...
if hint < 0 || hint > int(maxSliceCap(t.bucket.size)) { hint = 0 } // initialize Hmap if h == nil { h = new(hmap) } //生成hash种子 h.hash0 = fastrand() // find size parameter which will hold the requested # of elements ...
// grow allocates a new empty span from the heap and initializes it for c's size class. func (c *mcentral) grow() *mspan { // 根据mcentral的类型计算需要申请的span的大小(除以8K = 有多少页)和可以保存多少个元素 npages := uintptr(class_to_allocnpages[c.spanclass.sizeclass()]) size...
This call (among other things) initializes the suite with a fresh instance of t and protects tests from undefined behavior (such as data races). Autofix is disabled because in the most cases it requires rewriting the assertions in the subtest and can leads to dead code. The checker is ...