ctags[tag] = true
	}
	// TODO: ReleaseTags (need to load default)
	key := dir

	// explicit on GOOS and GOARCH as global cache will use "all" cached packages for
	// an indirect imported package. See https://github.com/golang/go/issues/21181
	// for more detail.
	tags = append(tags, context.GOOS, context.GOARCH)
	sort.Strings(tags)

	for _, tag := range tags {
		if ctags[tag] {
			key += "," + tag
			ctags[tag] = false

</p>

<h2 id="model">Memory Model</h2>

<p>
The following formal definition of Go's memory model closely follows
the approach presented by Hans-J. Boehm and Sarita V. Adve in
“<a href="https://www.hpl.hp.com/techreports/2008/HPL-2008-56.pdf">Foundations of the C++ Concurrency Memory Model</a>”,
published in PLDI 2008.
The definition of data-race-free programs and the guarantee of sequential consistency