Does gc Go (specifically go1.11) pre-allocates a chunk of memory and take from it for each allocation (like JVM), or it allocates every time a variable is created, and is it a kernel call (malloc)?
If it is one kernel call per allocation, that would make variable creation expensive. How can I force allocation on the stack/heap?
分享 This is covered in various places, like the FAQ:
How do I know whether a variable is allocated on the heap or the stack?
From a correctness standpoint, you don't need to know. Each variable in Go exists as long as there are references to it. The storage location chosen by the implementation is irrelevant to the semantics of the language.
The storage location does have an effect on writing efficient programs. When possible, the Go compilers will allocate variables that are local to a function in that function's stack frame. However, if the compiler cannot prove that the variable is not referenced after the function returns, then the compiler must allocate the variable on the garbage-collected heap to avoid dangling pointer errors. Also, if a local variable is very large, it might make more sense to store it on the heap rather than the stack.
In the current compilers, if a variable has its address taken, that variable is a candidate for allocation on the heap. However, a basic escape analysis recognizes some cases when such variables will not live past the return from the function and can reside on the stack.
Go's memory allocation is carefully optimized for its needs, for example with a custom malloc. I suspect you have a slightly different underlying question/problem that you're struggling with - it would be better to ask that instead. If this is just exploration/curiosity, you'll have to make your question much more specific.
分享
