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doc/faq: explain why goroutines are anonymous

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Fixes #22770.

Change-Id: Ief62043fb6895e215d2530d2a3bf88f7ea58c875
Reviewed-on: https://go-review.googlesource.com/80195
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Rob Pike 2017-11-28 16:05:59 +11:00
parent a5b759aab8
commit 992ce90f66
1 changed files with 47 additions and 0 deletions
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doc/go_faq.html
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@ -1476,6 +1476,53 @@ For more detail on this topic see the talk entitled,
<a href="//blog.golang.org/2013/01/concurrency-is-not-parallelism.html">Concurrency
is not Parallelism</a>.
<h3 id="no_goroutine_id">
Why is there no goroutine ID?</h3>
<p>
Goroutines do not have names; they are just anonymous workers.
They expose no unique identifier, name, or data structure to the programmer.
Some people are surprised by this, expecting the <code>go</code>
statement to return some item that can be used to access and control
the goroutine later.
</p>
<p>
The usage patterns that develop when threads and goroutines are
named can restrict what a library using them can do.
Goroutines
are anonymous so the full Go language is available when programming
concurrent code.
</p>
<p>
For example, once one names a goroutine and constructs a model around
it, it becomes special, and one is tempted to associate all computation
with that goroutine, ignoring the possibility
of using multiple, possibly shared goroutines for the processing.
If the <code>net/http</code> package associated per-request
state with a goroutine,
clients would be unable to use more goroutines
when serving a request.
</p>
<p>
Also, experience with libraries, such as those for graphics systems,
that require all processing to occur on the "main thread",
shows how awkward and limiting the approach can be when
deployed in a concurrent language.
The very existence of a special thread or goroutine forces
the programmer to distort the program to avoid crashes
and other problems caused by inadvertently operating
on the wrong thread.
</p>
<p>
For those cases where a particular goroutine is truly special,
the language provides features such as channels that can be
used in flexible ways to interact with it.
</p>
<h2 id="Functions_methods">Functions and Methods</h2>
<h3 id="different_method_sets">