go/doc/go1.3.html

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<h2 id="introduction">Introduction to Go 1.3</h2>

<p>
The latest Go release, version 1.3, arrives six months after 1.2,
and contains no language changes.
It does have some important developments, though,
including a refinement to the memory model regarding synchronization,
precise garbage collection,
significant performance improvements across the board,
and support for Google's Native Client architecture (NaCl).
As always, Go 1.3 keeps the <a href="/doc/go1compat.html">promise
of compatibility</a>,
and almost everything 
will continue to compile and run without change when moved to 1.3.
</p>

<h2 id="os">Changes to the supported operating systems and architectures</h2>

<h3 id="nacl">Support for Native Client</h3>
<p>
TODO
</p>

<h3 id="solaris">Support for Solaris</h3>

<p>
TODO
</p>


<h3 id="windows2000">Removal of support for Windows 2000</h3>

<p>
Microsoft stopped supporting Windows 2000 in 2010.
Since it has <a href="https://codereview.appspot.com/74790043">implementation difficulties</a>
regarding exception handling (signals in Unix terminology),
as of Go 1.3 it is not supported by Go either.
</p>


<h2 id="memory">Changes to the memory model</h2>

<p>
The Go 1.3 memory model <a href="https://codereview.appspot.com/75130045">adds a new rule</a>
concerning sending and receiving on buffered channels,
to make explicit that a buffered channel can be used as a simple
semaphore, using a send into the
channel to acquire and a receive from the channel to release.
This is not a language change, just a clarification about an expected property of communication.
</p>

<h2 id="impl">Changes to the implementations and tools</h2>

<h3 id="stacks">Stack</h3>

<p>
Go 1.3 has changed the implementation of goroutine stacks away from the old,
"segmented" model to a contiguous model.
When a goroutine needs more stack
than is available, its stack is transferred to a larger single block of memory.
The overhead of this transfer operation amortizes well and eliminates the old "hot spot"
problem when a calculation repeatedly steps across a segment boundary.
Details including performance numbers are in this
<a href="http://golang.org/s/contigstacks">design document</a>.
</p>

<h3 id="stack_size">Stack size</h3>

<p>
Go 1.2 increased the minimum stack size to 8 kilobytes; with the new stack model, it has been
put back to 4 kilobytes.
</p>

<p>
<em>Updating</em>: TODO
</p>

<h3 id="garbage_collector">Changes to the garbage collector</h3>

<p>
precision (TODO what to say)
liveness (TODO what to say)
</p>

<h3 id="liblink">The linker</h3>

<p>
TODO compiler/linker boundary moved
</p>

<p>
<em>Updating</em>: TODO
</p>

<h3 id="gccgo">Status of gccgo</h3>

<p>
TODO
</p>

<h3 id="gocmd">Changes to the go command</h3>

<p>
TODO
cmd/go, go/build: support .m files (CL 60590044)
cmd/go: add -exec to 'go run' and 'go test' (CL 68580043)
cmd/go: cover -atomic for -race (CL 76370043)
</p>

<h3 id="misc">Miscellany</h3>

<ul>
<li> TODO: misc/benchcmp: removed and replaced by go.tools/cmd/benchcmp (CL 47980043)</li>
<li> TODO: misc/dist: renamed misc/makerelease (CL 39920043)</li>
</ul>


<h2 id="performance">Performance</h2>

<p>
TODO
</p>

<ul> 

<li>
TODO
</li>

</ul>

<h2 id="library">Changes to the standard library</h2>

<p>
TODO: Which should be called out?
</p>

<p>
There is an important new type added to the standard library: <a href="/pkg/sync/pool/"><code>sync/pool</code></a>.
TODO: sync: add Pool (CL 41860043, 46010043)
</p>



<h3 id="new_packages">New packages</h3>

<p>
No new packages appear in the core libraries in Go 1.3.
</p>

<h3 id="minor_library_changes">Minor changes to the library</h3>

<p>
The following list summarizes a number of minor changes to the library, mostly additions.
See the relevant package documentation for more information about each change.
</p>

<ul>

<li> TODO: cmplx.Pow(0, x): https://codereview.appspot.com/76940044</li>
<li> TODO: crypto/tls: ServerName or InsecureSkipVerify (CL 67010043)</li>
<li> TODO: crypto/tls: add DialWithDialer (CL 68920045)</li>
<li> TODO: crypto/tls: report TLS version in ConnectionState (CL 68250043)</li>
<li> TODO: crypto/x509: support CSRs (CL 49830048)</li>
<li> TODO: fmt %F: 77580044</li>
<li> TODO: liblink: pull linker i/o into separate liblink C library (CL 35790044)</li>
<li> TODO: net/http: add Request.TLS (CL 52660047)</li>
<li> TODO: net/http: add Server.ErrorLog; log and test TLS handshake errors (CL 70250044)</li>
<li> TODO: net/http: add Server.SetKeepAlivesEnabled (CL 69670043)</li>
<li> TODO: net/http: add Transport.TLSHandshakeTimeout; set it by default (CL 68150045)</li>
<li> TODO: net/http: add optional Server.ConnState callback (CL 69260044)</li>
<li> TODO: net/http: use TCP Keep-Alives on DefaultTransport's connections (CL 68330046)</li>
<li> TODO: net/http: use TCP keep-alives for ListenAndServe and ListenAndServeTLS (CL 48300043)</li>
<li> TODO: net: add Dialer.KeepAlive option (CL 68380043)</li>
<li> TODO: net: enable fast socket creation using SOCK_CLOEXEC and Accept4 on FreeBSD 10 (69100043)</li>
<li> TODO: os/exec: fix Command with relative paths (CL 59580044)</li>
<li> TODO: regexp: add one-pass optimization from RE2 (CL 13345046)</li>
<li> TODO: runtime/debug: add SetPanicOnFault (CL 66590044)</li>
<li> TODO: runtime: output how long goroutines are blocked (CL 50420043)</li>
<li> TODO: runtime: better handling of defers, reduces goroutine memory footprint by 2K (CL 42750044)</li>
<li> TODO: runtime: faster GC: concurrent sweep, better parallelization, 8K pages (up to 50-70% pause reduction) (CL 46430043, 46860043, 58230043)</li>
<li> TODO: runtime/race: faster by ~40% (CL 55100044)</li>
<li> TODO: strconv.CanBackquote rejects U+007F CL 77300043</li>
<li> TODO: syscall: add Accept4 for freebsd (CL 68880043)</li>
<li> TODO: syscall: add NewCallbackCDecl to use for windows callbacks (CL 36180044)</li>
<li> TODO: syscall: add support for FreeBSD 10 (CL 56770044, 56980043)</li>
<li> TODO: testing: add b.RunParallel function (CL 57270043)</li>
<li> TODO: testing: diagnose buggy tests that panic(nil) (CL 55780043)</li>
<li> TODO: unicode: upgrade from Unicode 6.2.0 to 6.3.0 (CL 65400044)</li>
</ul>