// bitmap stores the pointer/scalar bitmap for the words in // this arena. See mbitmap.go for a description. Use the // heapBits type to access this. bitmap [heapArenaBitmapBytes]byte //arenas is the heap arena map. It points to the metadata for//the heap for every arena frame...
x = unsafe.Pointer(c.tiny + off) c.tinyoffset = off + size c.local_tinyallocs++ releasem(mp) return x } ... } ... } ... } 当内存块中不包含空闲的内存时,下面的这段代码会先从线程缓存找到跨度类对应的内存管理单元runtime.mspan,调用runtime.nextFreeFast获取空闲的内存;当不存在空闲内存...
// Not enough room in the current arena. Allocate more // arena space. This may not be contiguous with the // current arena, so we have to request the full ask. av, asize := h.sysAlloc(ask) if av == nil { print("runtime: out of memory: cannot allocate ", ask, "-byte blo...
or// nil if there is no current tiny block./// tiny is a heap pointer. Since mcache is in non-GC'd memory,// we handle it by clearing it in releaseAll during mark// termination.///
// growslice allocates new backing store for a slice./// arguments:/// oldPtr = pointer to the slice's backing array// newLen = new length (= oldLen + num)// oldCap = original slice's capacity.// num = number of elements being added// et = element type/// return ...
The new build-in functionallocates memory(仅仅分配空间). The first argument is a type, not a value, and the value returned is a pointer to a newly allocated zero value of that type.内置函数new分配空间。传递给new函数的是一个类型,不是一个值。返回值是 指向这个新分配的零值的指针。
在Tiger.Eat 方法中,由于只是简单的 for 循环空转无法走到检查点,因此这种协作式抢占无法生效 非协作式抢占:在 go 1.14 之后,启用了基于信号量实现的非协作抢占机制. Monitor 探测到 g 超时会发送抢占信号,g 所属 m 收到信号后,会修改 g 的 栈程序计数器 pc 和栈顶指针 sp 为其注入 asyncPreempt 函数. ...
funcDijkstraWritePointer(slot*unsafe.Pointer,ptr unsafe.Pointer)shade(ptr)//先将新下游对象 ptr 标记为灰色 *slot = ptr}//说明:添加下游对象(当前下游对象slot, 新下游对象ptr) { //step 1 标记灰色(新下游对象ptr) //step 2 当前下游对象slot = 新下游对象ptr }//场景:A.添加下游对象(nil, B) /...
引用自:https://draveness.me/golang/docs/part3-runtime/ch07-memory/go... 应用代表:GO、Java(如果使用 CMS 这种基于标记-清除,采用分配的方式为空闲链表分配) 问题:相比线性分配方式的 bump-pointer 分配操作(top += size),空闲链表的分配操作过重,例如在 GO 程序的 pprof 图中经常可以看到 mallocgc()...
bitmap:标识对应的内存地址是否被使用,2位标识一个内存地址,一个标识shoud scan,一个标识is pointer。bitmap大小怎么算出来的?每个地址8byte,共512G/8个地址,bitmap中的每个byte能标识4个地址,因此大小为:512G/8/4=16G spans []mspan: 记录 arena 区域页号(page number)和 mspan 的映射关系。一页8K,每个 ...