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| <title>Go, Networked (January 21, 2010)</title> |
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| <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> |
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| <br><br> |
| <div style="color: #ffcc00;"> |
| <!-- <h3><i>rsc@google.com</i></h3> --> |
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