Highlights of Go 1.1
2 likes937 views
This document summarizes the key highlights of Go 1.1, including improvements to method values, return handling, the bufio.Scanner utility, size of ints, heap size on different platforms, nanosecond timing capabilities, performance improvements of 30-40%, highlights of performance optimizations, and introduction of a race detector. The full release notes can be found at http://golang.org/doc/go1.1.
![Nanosecond timing
• FreeBSD, Linux, NetBSD, OpenBSD, OS X time package
has nanosecond precision
• time.Round and time.Truncate to round up/down to
nearest multiples of any time.Duration
t, _ := time.Parse("2006 Jan 02 15:04:05", "2012 Dec
07 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"))!
}!
www.cloudflare.com!](https://image.slidesharecdn.com/cloudflarejgc-highlightsofgo1-140111095348-phpapp01/85/Highlights-of-Go-1-1-7-320.jpg)
![Race Detector
• http://golang.org/doc/articles/race_detector.html
• Detects concurrent access by two goroutines to the
same variable where one access is write
func 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!
}!
• go build –race example.go
www.cloudflare.com!](https://image.slidesharecdn.com/cloudflarejgc-highlightsofgo1-140111095348-phpapp01/85/Highlights-of-Go-1-1-10-320.jpg)
Highlights of Go 1.1
- 1. Highlights of Go 1.1 May 29, 2013 John Graham-Cumming www.cloudflare.com!
- 2. Method Values • Function value bound to specific receiver type 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"))! }! www.cloudflare.com!
- 3. Change to return handling • return statement not needed at end of functions if function termination is unambiguous func even() int {! for {! if i := rand.Intn(100); i%2 == 0 {! return i! }! }! }! • Worth reading the specification on ‘terminating statements’ • http://golang.org/ref/spec#Terminating_statements www.cloudflare.com!
- 4. bufio.Scanner • Simple, fast type for doing command tasks like reading os.Stdin line by line, or reading word by word from a file scanner := bufio.NewScanner(os.Stdin)! ! for scanner.Scan() {! fmt.Println(scanner.Text()! }! ! if err := scanner.Err(); err != nil {! // Handle error! }! • Built in scanners for lines, words, characters and runes • Can provide a custom scanner function www.cloudflare.com!
- 5. 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 have trouble x := ^uint32(0) i := int(x) ! ! fmt.Println(i)! !// x is 0xffffffff! !// i is -1 on 32-bit systems, ! !// 0xffffffff on 64-bit! • Slice indexes are ints which means they can have 2 billion members www.cloudflare.com!
- 6. 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 already had massive heaps • Experimental support for: linux/arm, freebsd/arm, netbsd/386, amd64 and arm, openbsd/386 and amd64 www.cloudflare.com!
- 7. Nanosecond timing • FreeBSD, Linux, NetBSD, OpenBSD, OS X time package has nanosecond precision • time.Round and time.Truncate to round up/down to nearest multiples of any time.Duration t, _ := time.Parse("2006 Jan 02 15:04:05", "2012 Dec 07 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"))! }! www.cloudflare.com!
- 8. 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-performanceimprovements-part-2 • http://dave.cheney.net/2013/05/28/go-11-performanceimprovements-part-3 • Dave’s summary: 30-40% performance increase is real www.cloudflare.com!
- 9. Performance Highlights • Code generation improvements across all three gc compilers • Improvements to inlining • Reduction in stack usage • Parallel garbage collector. • More precise garbage collection, which reduces the size of the heap, leading to lower GC pause times. • New runtime scheduler; tight integration of the scheduler with the net package • Parts of the runtime and standard library have been rewritten in assembly to take advantage of specific bulk move or crypto instructions. www.cloudflare.com!
- 10. Race Detector • http://golang.org/doc/articles/race_detector.html • Detects concurrent access by two goroutines to the same variable where one access is write func 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! }! • go build –race example.go www.cloudflare.com!
- 11. 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 www.cloudflare.com!