_content/talks/2010/go_talk-20100121.html - website - Git at Google

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 <img src="support/bumper480x270.png" style="margin: -135px 0 0 0;"/>
 </div>
 <br/>
 <img src="support/go-logo-white.png">
 <br/>
 <br/>
 <h1 style="padding-right: 0pt; margin-right: 0pt; color: #0066cc; font-size: 250%; border-bottom: 0px;">The Go Programming Language</h1>
 <div style="color: #ffcc00;">
 <h2>Russ Cox</h2>
 <!-- <h3><i>rsc@google.com</i></h3> -->
 <br/>
 <h3>CNS Winter Research Review<br/><br/>January 21, 2010</h3>
 <br/>
 <br/>
 <!--
 <h4><i>click to start; then left/right arrow to change slides</i></h4> -->
 </div>
 </div>

 <div class="slide">
 	<h1>Go</h1>

 	<h2>New</h2>
 	<h2>Experimental</h2>
 	<h2>Concurrent</h2>
 	<h2>Garbage-collected</h2>
 	<h2>Systems</h2>
 	<h2>Language</h2>
 </div>

 <div class="slide">
 	<h1>Hello, world</h1>
 <pre>
 package main

 import "fmt"

 func main() {
 	fmt.Printf("Hello, 世界\n")
 }
 </pre>
 </div>

 <div class="slide">
 	<h1>History</h1>

 	<h2>Design started in late 2007.</h2>
 	<h2>Implementation starting to work mid-2008.</h2>
 	<h2>Released as an open source project in November 2009.</h2>
 	<h2>Work continues.</h2>
 	<h2>Robert&nbsp;Griesemer, Ken&nbsp;Thompson, Rob&nbsp;Pike, Ian&nbsp;Lance&nbsp;Taylor, Russ&nbsp;Cox, many others</h2>
 </div>

 <div class="slide">
 	<h1>Goals and Motivation</h1>

 	<h2>Go fast!</h2>
 	<h2>Make programming fun again.</h2>
 	<h2>Targeted at systems software, broadly.</h2>
 </div>

 <div class="slide">
 	<h1>Why isn't programming fun?</h1>

 	<div class="incremental">
 	<h2>Compiled, statically-typed languages (C, C++, Java) require too much typing and too much typing:</h2>

 	<ul>
 		<li>verbose, lots of repetition</li>
 		<li>too much focus on type hierarchy</li>
 		<li>types get in the way as much as they help</li>
 		<li>compiles take far too long</li>
 	</ul>
 	</div>

 	<div class="incremental">
 	<h2>Dynamic languages (Python, JavaScript) fix these problems (no more types, no more compiler) but introduce others:</h2>

 	<ul>
 		<li>errors at run time that should be caught statically</li>
 		<li>no compilation means slow code</li>
 	</ul>
 	</div>

 	<h2 class="incremental">Can we combine the best of both?</h2>
 </div>

 <div class="slide">
 	<h1>Why a new language?</h1>

 	<div class="incremental">
 	<h2>No new systems language in 10+ years.</h2>
 	<h2>Current languages designed before ...</h2>
 	<h3>... rise of large-scale, networked and multicore computing</h3>
 	<h3>... rise of Internet-scale distributed development (many libraries)</h3>
 	</div>
 </div>

 <div class="slide">
 	<h1>Go</h1>

 	<h2>Make the language fast.</h2>
 	<h2>Make the tools fast.</h2>
 </div>

 <div class="slide">
 	<h1>Compilation Demo</h1>

 	<h2>Build all standard Go packages: ~120,000 lines of code.</h2>
 </div>

 <div class="slide">
 	<h1>Go in one slide</h1>

 	<h2 class="incremental">Lightweight syntax.</h2>

 	<h2 class="incremental">Static types: enough to compile well, but inferred much of the time.</h2>

 	<h2 class="incremental">Methods: on any type, orthogonal to type system.</h2>

 	<h2 class="incremental">Abstract types: interface values, relations inferred statically.</h2>

 	<h2 class="incremental">Visibility: inferred from case of name.</h2>

 	<h2 class="incremental">First-class functions.</h2>

 	<h2 class="incremental">Garbage collection.</h2>

 	<br/>

 	<h2 class="incremental">Lightweight feel of a scripting language but compiled.</h2>
 </div>

 <div class="slide">
 	<h1>Go, concurrently</h1>

 	<h2>Cheap to create a new flow of control (goroutine):</h2>

 <pre>
 func main() {
 	go expensiveComputation(x, y, z)
 	anotherExpensiveComputation(a, b, c)
 }
 </pre>

 	<h2>Two expensive computations in parallel.</h2>
 </div>

 <div class="slide">
 	<h1>Go, concurrently</h1>

 	<h2>Cheap to create a new flow of control (goroutine):</h2>

 <pre>
 	for {
 		rw := l.Accept()
 		conn := newConn(rw, handler)
 		go conn.serve()
 	}
 </pre>

 	<h2>Concurrent web server.</h2>
 	<h2>Network connections multiplexed onto epoll.</h2>
 		<ul>
 		<li>many blocked Read calls != many blocked OS threads</li>
 		</ul>

 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>Use explicit messages to communicate and synchronize.</h2>

 <pre>
 func computeAndSend(ch chan int, x, y, z int) {
 	ch &lt;- expensiveComputation(x, y, z)
 }

 func main() {
 	ch := make(chan int)
 	go computeAndSend(ch, x, y, z)
 	v2 := anotherExpensiveComputation(a, b, c)
 	v1 := &lt;-ch
 	fmt.Println(v1, v2)
 }
 </pre>
 	<h2>Notice communication of result in addition to synchronization.</h2>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client</h2>

 <pre>
 func (client *Client) Call(method string, args, reply interface{}) os.Error {
     // Send RPC message.
     call := client.Go(method, args, reply, nil)

     // Read reply from Done channel.
     &lt;-call.Done

     return call.Error
 }
 </pre>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client demux</h2>

 <pre>
 func (client *Client) input() {
 	for {
 		resp := client.readResponse()
 		client.mutex.Lock()
 		c := client.pending[resp.Seq]
 		client.pending[resp.Seq] = c, false
 		client.mutex.Unlock()
 		if resp.Error != "" {
 			c.Error = os.ErrorString(resp.error)
 		}
 		resp.Decode(c.Reply)
 		c.Done &lt;- c
 	}
 }
 </pre>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client demux</h2>

 <pre>
 func (client *Client) input() {
 	for {
 		<font style="color: black;">resp := client.readResponse()</font>
 		client.mutex.Lock()
 		c := client.pending[resp.Seq]
 		client.pending[resp.Seq] = c, false
 		client.mutex.Unlock()
 		if resp.Error != "" {
 			c.Error = os.ErrorString(resp.error)
 		}
 		resp.Decode(c.Reply)
 		c.Done &lt;- c
 	}
 }
 </pre>
 <h2>Read response from network.</h2>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client demux</h2>

 <pre>
 func (client *Client) input() {
 	for {
 		resp := client.readResponse()
 		<font style="color: black;">client.mutex.Lock()
 		c := client.pending[resp.Seq]
 		client.pending[resp.Seq] = c, false
 		client.mutex.Unlock()</font>
 		if resp.Error != "" {
 			c.Error = os.ErrorString(resp.error)
 		}
 		resp.Decode(c.Reply)
 		c.Done &lt;- c
 	}
 }
 </pre>
 <h2>Look up request by sequence number.</h2>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client demux</h2>

 <pre>
 func (client *Client) input() {
 	for {
 		resp := client.readResponse()
 		client.mutex.Lock()
 		c := client.pending[resp.Seq]
 		client.pending[resp.Seq] = c, false
 		client.mutex.Unlock()
 		<font style="color: black;">if resp.Error != "" {
 			c.Error = os.ErrorString(resp.error)
 		}
 		resp.Decode(c.Reply)</font>
 		c.Done &lt;- c
 	}
 }
 </pre>
 <h2>Decode response fields from payload.</h2>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client demux</h2>

 <pre>
 func (client *Client) input() {
 	for {
 		resp := client.readResponse()
 		client.mutex.Lock()
 		c := client.pending[resp.Seq]
 		client.pending[resp.Seq] = c, false
 		client.mutex.Unlock()
 		if resp.Error != "" {
 			c.Error = os.ErrorString(resp.error)
 		}
 		resp.Decode(c.Reply)
 		<font style="color: black;">c.Done &lt;- c</font>
 	}
 }
 </pre>
 <h2>Tell client that it finished.</h2>
 </div>

 <div class="slide">
 	<h1>Go, synchronized</h1>

 	<h2>RPC client demux</h2>

 <pre>
 func (client *Client) input() {
 	for {
 		resp := client.readResponse()
 		client.mutex.Lock()
 		c := client.pending[resp.Seq]
 		client.pending[resp.Seq] = c, false
 		client.mutex.Unlock()
 		if resp.Error != "" {
 			c.Error = os.ErrorString(resp.error)
 		}
 		resp.Decode(c.Reply)
 		c.Done &lt;- c
 	}
 }
 </pre>

 <h2>Can create multiple Calls with same Done channel
 and distinguish which finished by inspecting value sent on channel.
 </h2>

 </div>

 <div class="slide">
 	<h1>Goroutine demo</h1>

 	<h2>Chain together 100,000 goroutines connected by 100,001 channels.</h2>

 	<h2>Send a value to one end of the chain.</h2>

 	<h2>Each passes it along, increments.</h2>

 	<h2>Receive value out the other end of the chain.</h2>
 </div>


 <div class="slide">
 	<h1>Go Status</h1>
 </div>

 <div class="slide">
 	<h1>Go Status</h1>

 	<h2>Open source:</h2>
 	<ul>
 	<li>released on November 10, 2009
 	<li>regular releases (~ weekly)
 	<li>all development done in public Mercurial repository
 	<li>outside contributions welcome
 	<li>two independent compiler implementations
 	<li>XML, JSON, HTTP, TLS/SSL, native RPC, (network channels,) ...
 	</ul>
 </div>

 <div class="slide">
 	<h1>Go Status</h1>

 	<h2>Open source</h2>

 	<h2>Portable:</h2>
 	<ul>
 	<li>FreeBSD, Linux, OS X (x86, x86-64)
 	<li>(in progress) Linux arm, Native Client x86, Windows x86.
 	</ul>
 </div>

 <div class="slide">
 	<h1>Go Status</h1>

 	<h2>Open source</h2>
 	<h2>Portable</h2>

 	<h2>Still in progress, experimental.  Yet to come:</h2>
 	<ul>
 	<li>production garbage collector
 	<li>generics?
 	<li>exceptions?
 	<li>unions or sum types?
 	</ul>
 </div>

 <div class="slide titlepage">
 	<h1>Questions?</h1>
 	<br><br>
 	<center>
 	<img src="support/bumper640x360.png">
 	</center>
 	<br><br>
 	<div style="color: #ffcc00;">
 	<!-- <h3><i>rsc@google.com</i></h3> -->
 	</div>
 </div>

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	"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
	<head>
	<title>Go, Networked (January 21, 2010)</title>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<meta name="font-size-adjustment" content="-1" />
	<link rel="stylesheet" href="support/slidy.css"
	type="text/css" media="screen, projection, print" />
	<script src="support/slidy.js" type="text/javascript">
	</script>
	</head>
	<body>
	<!-- this defines the slide background -->

	<div class="background">

	<div class="header">
	<!-- sized and colored via CSS -->
	</div>

	<div class="footer"></div>
	</div>

	<div class="slide titlepage">
	<div style="height: 135px; width: 480px; overflow: hidden; position: fixed; top: auto; bottom: 10px; left: auto; right: 0; ">
	<img src="support/bumper480x270.png" style="margin: -135px 0 0 0;"/>
	</div>
	<br/>
	<img src="support/go-logo-white.png">
	<br/>
	<br/>
	<h1 style="padding-right: 0pt; margin-right: 0pt; color: #0066cc; font-size: 250%; border-bottom: 0px;">The Go Programming Language</h1>
	<div style="color: #ffcc00;">
	<h2>Russ Cox</h2>
	<!-- <h3><i>rsc@google.com</i></h3> -->
	<br/>
	<h3>CNS Winter Research Review<br/><br/>January 21, 2010</h3>
	<br/>
	<br/>
	<!--
	<h4><i>click to start; then left/right arrow to change slides</i></h4> -->
	</div>
	</div>

	<div class="slide">
	<h1>Go</h1>

	<h2>New</h2>
	<h2>Experimental</h2>
	<h2>Concurrent</h2>
	<h2>Garbage-collected</h2>
	<h2>Systems</h2>
	<h2>Language</h2>
	</div>

	<div class="slide">
	<h1>Hello, world</h1>
	<pre>
	package main

	import "fmt"

	func main() {
	fmt.Printf("Hello, 世界\n")
	}
	</pre>
	</div>

	<div class="slide">
	<h1>History</h1>

	<h2>Design started in late 2007.</h2>
	<h2>Implementation starting to work mid-2008.</h2>
	<h2>Released as an open source project in November 2009.</h2>
	<h2>Work continues.</h2>
	<h2>Robert Griesemer, Ken Thompson, Rob Pike, Ian Lance Taylor, Russ Cox, many others</h2>
	</div>

	<div class="slide">
	<h1>Goals and Motivation</h1>

	<h2>Go fast!</h2>
	<h2>Make programming fun again.</h2>
	<h2>Targeted at systems software, broadly.</h2>
	</div>

	<div class="slide">
	<h1>Why isn't programming fun?</h1>

	<div class="incremental">
	<h2>Compiled, statically-typed languages (C, C++, Java) require too much typing and too much typing:</h2>

	<ul>
	<li>verbose, lots of repetition</li>
	<li>too much focus on type hierarchy</li>
	<li>types get in the way as much as they help</li>
	<li>compiles take far too long</li>
	</ul>
	</div>

	<div class="incremental">
	<h2>Dynamic languages (Python, JavaScript) fix these problems (no more types, no more compiler) but introduce others:</h2>

	<ul>
	<li>errors at run time that should be caught statically</li>
	<li>no compilation means slow code</li>
	</ul>
	</div>

	<h2 class="incremental">Can we combine the best of both?</h2>
	</div>

	<div class="slide">
	<h1>Why a new language?</h1>

	<div class="incremental">
	<h2>No new systems language in 10+ years.</h2>
	<h2>Current languages designed before ...</h2>
	<h3>... rise of large-scale, networked and multicore computing</h3>
	<h3>... rise of Internet-scale distributed development (many libraries)</h3>
	</div>
	</div>

	<div class="slide">
	<h1>Go</h1>

	<h2>Make the language fast.</h2>
	<h2>Make the tools fast.</h2>
	</div>

	<div class="slide">
	<h1>Compilation Demo</h1>

	<h2>Build all standard Go packages: ~120,000 lines of code.</h2>
	</div>

	<div class="slide">
	<h1>Go in one slide</h1>

	<h2 class="incremental">Lightweight syntax.</h2>

	<h2 class="incremental">Static types: enough to compile well, but inferred much of the time.</h2>

	<h2 class="incremental">Methods: on any type, orthogonal to type system.</h2>

	<h2 class="incremental">Abstract types: interface values, relations inferred statically.</h2>

	<h2 class="incremental">Visibility: inferred from case of name.</h2>

	<h2 class="incremental">First-class functions.</h2>

	<h2 class="incremental">Garbage collection.</h2>

	<br/>

	<h2 class="incremental">Lightweight feel of a scripting language but compiled.</h2>
	</div>

	<div class="slide">
	<h1>Go, concurrently</h1>

	<h2>Cheap to create a new flow of control (goroutine):</h2>

	<pre>
	func main() {
	go expensiveComputation(x, y, z)
	anotherExpensiveComputation(a, b, c)
	}
	</pre>

	<h2>Two expensive computations in parallel.</h2>
	</div>

	<div class="slide">
	<h1>Go, concurrently</h1>

	<h2>Cheap to create a new flow of control (goroutine):</h2>

	<pre>
	for {
	rw := l.Accept()
	conn := newConn(rw, handler)
	go conn.serve()
	}
	</pre>

	<h2>Concurrent web server.</h2>
	<h2>Network connections multiplexed onto epoll.</h2>
	<ul>
	<li>many blocked Read calls != many blocked OS threads</li>
	</ul>

	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>Use explicit messages to communicate and synchronize.</h2>

	<pre>
	func computeAndSend(ch chan int, x, y, z int) {
	ch <- expensiveComputation(x, y, z)
	}

	func main() {
	ch := make(chan int)
	go computeAndSend(ch, x, y, z)
	v2 := anotherExpensiveComputation(a, b, c)
	v1 := <-ch
	fmt.Println(v1, v2)
	}
	</pre>
	<h2>Notice communication of result in addition to synchronization.</h2>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client</h2>

	<pre>
	func (client *Client) Call(method string, args, reply interface{}) os.Error {
	// Send RPC message.
	call := client.Go(method, args, reply, nil)

	// Read reply from Done channel.
	<-call.Done

	return call.Error
	}
	</pre>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client demux</h2>

	<pre>
	func (client *Client) input() {
	for {
	resp := client.readResponse()
	client.mutex.Lock()
	c := client.pending[resp.Seq]
	client.pending[resp.Seq] = c, false
	client.mutex.Unlock()
	if resp.Error != "" {
	c.Error = os.ErrorString(resp.error)
	}
	resp.Decode(c.Reply)
	c.Done <- c
	}
	}
	</pre>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client demux</h2>

	<pre>
	func (client *Client) input() {
	for {
	<font style="color: black;">resp := client.readResponse()</font>
	client.mutex.Lock()
	c := client.pending[resp.Seq]
	client.pending[resp.Seq] = c, false
	client.mutex.Unlock()
	if resp.Error != "" {
	c.Error = os.ErrorString(resp.error)
	}
	resp.Decode(c.Reply)
	c.Done <- c
	}
	}
	</pre>
	<h2>Read response from network.</h2>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client demux</h2>

	<pre>
	func (client *Client) input() {
	for {
	resp := client.readResponse()
	<font style="color: black;">client.mutex.Lock()
	c := client.pending[resp.Seq]
	client.pending[resp.Seq] = c, false
	client.mutex.Unlock()</font>
	if resp.Error != "" {
	c.Error = os.ErrorString(resp.error)
	}
	resp.Decode(c.Reply)
	c.Done <- c
	}
	}
	</pre>
	<h2>Look up request by sequence number.</h2>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client demux</h2>

	<pre>
	func (client *Client) input() {
	for {
	resp := client.readResponse()
	client.mutex.Lock()
	c := client.pending[resp.Seq]
	client.pending[resp.Seq] = c, false
	client.mutex.Unlock()
	<font style="color: black;">if resp.Error != "" {
	c.Error = os.ErrorString(resp.error)
	}
	resp.Decode(c.Reply)</font>
	c.Done <- c
	}
	}
	</pre>
	<h2>Decode response fields from payload.</h2>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client demux</h2>

	<pre>
	func (client *Client) input() {
	for {
	resp := client.readResponse()
	client.mutex.Lock()
	c := client.pending[resp.Seq]
	client.pending[resp.Seq] = c, false
	client.mutex.Unlock()
	if resp.Error != "" {
	c.Error = os.ErrorString(resp.error)
	}
	resp.Decode(c.Reply)
	<font style="color: black;">c.Done <- c</font>
	}
	}
	</pre>
	<h2>Tell client that it finished.</h2>
	</div>

	<div class="slide">
	<h1>Go, synchronized</h1>

	<h2>RPC client demux</h2>

	<pre>
	func (client *Client) input() {
	for {
	resp := client.readResponse()
	client.mutex.Lock()
	c := client.pending[resp.Seq]
	client.pending[resp.Seq] = c, false
	client.mutex.Unlock()
	if resp.Error != "" {
	c.Error = os.ErrorString(resp.error)
	}
	resp.Decode(c.Reply)
	c.Done <- c
	}
	}
	</pre>

	<h2>Can create multiple Calls with same Done channel
	and distinguish which finished by inspecting value sent on channel.
	</h2>

	</div>

	<div class="slide">
	<h1>Goroutine demo</h1>

	<h2>Chain together 100,000 goroutines connected by 100,001 channels.</h2>

	<h2>Send a value to one end of the chain.</h2>

	<h2>Each passes it along, increments.</h2>

	<h2>Receive value out the other end of the chain.</h2>
	</div>


	<div class="slide">
	<h1>Go Status</h1>
	</div>

	<div class="slide">
	<h1>Go Status</h1>

	<h2>Open source:</h2>
	<ul>
	<li>released on November 10, 2009
	<li>regular releases (~ weekly)
	<li>all development done in public Mercurial repository
	<li>outside contributions welcome
	<li>two independent compiler implementations
	<li>XML, JSON, HTTP, TLS/SSL, native RPC, (network channels,) ...
	</ul>
	</div>

	<div class="slide">
	<h1>Go Status</h1>

	<h2>Open source</h2>

	<h2>Portable:</h2>
	<ul>
	<li>FreeBSD, Linux, OS X (x86, x86-64)
	<li>(in progress) Linux arm, Native Client x86, Windows x86.
	</ul>
	</div>

	<div class="slide">
	<h1>Go Status</h1>

	<h2>Open source</h2>
	<h2>Portable</h2>

	<h2>Still in progress, experimental. Yet to come:</h2>
	<ul>
	<li>production garbage collector
	<li>generics?
	<li>exceptions?
	<li>unions or sum types?
	</ul>
	</div>

	<div class="slide titlepage">
	<h1>Questions?</h1>
	<br><br>
	<center>
	<img src="support/bumper640x360.png">
	</center>
	<br><br>
	<div style="color: #ffcc00;">
	<!-- <h3><i>rsc@google.com</i></h3> -->
	</div>
	</div>

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