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Highlights of Go 1.1

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Talk on highlights of Go 1.1 presented at Golang London User Group, May 29, 2013.

Talk on highlights of Go 1.1 presented at Golang London User Group, May 29, 2013.

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  • Good presentation! Nitpick: slide 4 example is missing a closing parenthesis, should be:

    fmt.Println(scanner.Text())
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  • 1. www.cloudflare.com!Highlights of Go 1.1May 29, 2013John Graham-Cumming
  • 2. www.cloudflare.com!Method Values•  Function value bound to specific receivertype Prefixer struct {!prefix string!}!!func (p Prefixer) Add(s string) string {!return p.prefix + ": " + s!}!!func main() {!hawaii := Prefixer{"Aloha”}!fmt.Printf("%sn", hawaii.Add("Welcome to Honolulu"))!!adder := hawaii.Add!fmt.Printf("%sn", adder("Welcome to Honolulu"))!}!
  • 3. www.cloudflare.com!Change to return handling•  return statement not needed at end of functions iffunction termination is unambiguous•  Worth reading the specification on ‘terminatingstatements’•  http://golang.org/ref/spec#Terminating_statementsfunc even() int {!for {!if i := rand.Intn(100); i%2 == 0 {!return i!}!}!}!
  • 4. www.cloudflare.com!bufio.Scanner•  Simple, fast type for doing command tasks like readingos.Stdin line by line, or reading word by word from afile•  Built in scanners for lines, words, characters and runes•  Can provide a custom scanner functionscanner := bufio.NewScanner(os.Stdin)!!for scanner.Scan() {!fmt.Println(scanner.Text()!}!!if err := scanner.Err(); err != nil {!// Handle error!}!
  • 5. www.cloudflare.com!Size of int•  On 64-bit platforms int and uint are now 64 bits•  Elsewhere they are 32-bits.•  Couple of consequences:•  If your code was relying on them being 32-bits then you may havetrouble•  Slice indexes are ints which means they can have 2 billionmembersx := ^uint32(0) !// x is 0xffffffff!i := int(x) !// i is -1 on 32-bit systems, !! ! !// 0xffffffff on 64-bit!fmt.Println(i)!
  • 6. www.cloudflare.com!Heap size and Platforms•  On 64-bit machines heap can now be tens of GB•  No change on 32-bit•  If you were running off tip in recent months you alreadyhad massive heaps•  Experimental support for: linux/arm, freebsd/arm,netbsd/386, amd64 and arm, openbsd/386 andamd64
  • 7. www.cloudflare.com!Nanosecond timing •  FreeBSD, Linux, NetBSD, OpenBSD, OS X time packagehas nanosecond precision•  time.Round and time.Truncate to round up/down tonearest multiples of any time.Durationt, _ := time.Parse("2006 Jan 02 15:04:05", "2012 Dec07 12:15:30.918273645")!trunc := []time.Duration{!time.Nanosecond, time.Microsecond,!time.Millisecond, time.Second,!2 * time.Second, time.Minute,!10 * time.Minute, time.Hour, !}!for _, d := range trunc {!fmt.Printf("t.Truncate(%6s) = %sn", d,t.Truncate(d).Format("15:04:05.999999999"))!}!
  • 8. www.cloudflare.com!Performance•  Claimed 30 to 40% performance increase over Go 1.0.3•  Best analysis by Dave Cheney:•  http://dave.cheney.net/2013/05/21/go-11-performance-improvements•  http://dave.cheney.net/2013/05/25/go-11-performance-improvements-part-2•  http://dave.cheney.net/2013/05/28/go-11-performance-improvements-part-3•  Dave’s summary: 30-40% performance increase is real
  • 9. www.cloudflare.com!Performance Highlights•  Code generation improvements across all three gccompilers•  Improvements to inlining•  Reduction in stack usage•  Parallel garbage collector. •  More precise garbage collection, which reduces the sizeof the heap, leading to lower GC pause times.•  New runtime scheduler; tight integration of the schedulerwith the net package•  Parts of the runtime and standard library have beenrewritten in assembly to take advantage of specific bulkmove or crypto instructions.
  • 10. www.cloudflare.com!Race Detector •  http://golang.org/doc/articles/race_detector.html•  Detects concurrent access by two goroutines to thesame variable where one access is write•  go build –race example.gofunc main() {!c := make(chan bool)!m := make(map[string]string)!!go func() {!m["1"] = "a" // First conflicting access.!c <- true!}()!!m["2"] = "b" // Second conflicting access.!<-c!}!
  • 11. www.cloudflare.com!Full release notes•  http://golang.org/doc/go1.1•  Go 1.1 is backwards compatible with Go 1.0.3•  Go 1.2 targeted for December 1