Allocate uninitialized slice

Question

Is there some way to allocate an uninitialized slice in Go? A frequent pattern is to create a slice of a given size as a buffer, and then only use part of it to receive data. For example:

b := make([]byte, 0x20000) // b is zero initialized
n, err := conn.Read(b)
// do stuff with b[:n]. all of b is zeroed for no reason

This initialization can add up when lots of buffers are being allocated, as the spec states it will default initialize the array on allocation.

Answer 1

You can get non zeroed byte buffers from bufs.Cache.Get (or see CCache for the concurrent safe version). From the docs:

NOTE: The buffer returned by Get is not guaranteed to be zeroed. That's okay for e.g. passing a buffer to io.Reader. If you need a zeroed buffer use Cget.