| The State of Go |
| Where we are in February 2016 |
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| Francesc Campoy |
| Gopher at Google |
| @francesc |
| campoy@golang.org |
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| * Time flies |
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| Go 1.4 is one year old (happy birthday!) |
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| Go 1.5 is already 6 months old! |
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| Go 1.6 to be released sometime in February. |
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| Go 1.6 Candidate Release 1 was released on January 28th |
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| * Notes |
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| The slides are available on [[https://talks.golang.org/2016/state-of-go.slide]] |
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| Most of the code examples won't run except locally and using Go 1.6. |
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| The playground still runs Go 1.5. |
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| * Agenda |
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| Changes since Go 1.5: |
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| - the language |
| - the standard library |
| - the runtime |
| - the tooling |
| - the community |
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| * Changes to the language |
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| * Changes to the language |
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| None. |
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| This is a feature. |
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| * Changes to the standard library |
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| * Changes to the standard library |
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| A couple of new things, in order of excitement. |
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| - net/http |
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| - {text,html}/template |
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| - sort |
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| Also more speed and fewer bugs. |
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| * net/http |
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| If: |
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| - you're using HTTPS |
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| - and Go 1.6 |
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| you're using HTTP/2! |
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| * HTTP/2 |
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| At a high level, HTTP/2: |
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| - is binary, instead of textual |
| - is fully multiplexed, instead of ordered and blocking |
| - can therefore use one connection for parallelism |
| - uses header compression to reduce overhead |
| - allows servers to “push” responses proactively into client caches |
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| .link https://http2.golang.org/gophertiles |
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| * text/template |
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| Imagine that given a slice of strings: |
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| []string{"one", "two", "three"} |
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| We want to write a template that will generate: |
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| <ul> |
| <li>one</li> |
| <li>two</li> |
| <li>three</li> |
| </ul> |
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| What template would you write? |
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| * text/template: first try |
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| Naturally, I write this: |
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| .play state-of-go/template/old.go /`/,/`/ |
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| But unfortunately it's not exactly what I want! |
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| * text/template: let's fix it |
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| We need to be careful with the line breaks. |
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| .play state-of-go/template/fixed.go /`/,/`/ |
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| This works now, but ... I don't really like my code! |
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| * text/template: meet {{- and -}} |
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| Go 1.6 brings two new delimiters: |
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| - `{{-` |
| - `-}}` |
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| Similar to `{{` and `}}`, but _all_ white space on the `-` side will be trimmed. |
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| The template: |
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| {{23 -}} |
| < |
| {{- 45}} |
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| generates: |
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| 23<45 |
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| * text/template: back to our problem |
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| We can now have: |
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| - the result we expected |
| - without sacrificing the readability of our templates. |
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| .play state-of-go/template/new.go /`/,/`/ |
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| * text/template: the block action |
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| Go 1.6 brings also a new action named `block`. |
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| Let's see what it is useful for. |
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| * Factoring out repetition in templates |
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| Both `<ul>` share the same structure. |
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| {{define "presentation"}} |
| Authors: |
| <ul> |
| {{range .Authors}} |
| <li>{{.}}</li> |
| {{end}} |
| </ul> |
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| Topics: |
| <ul> |
| {{range .Topics}} |
| <li>{{.}}</li> |
| {{end}} |
| </ul> |
| {{end}} |
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| Templates can be used to avoid repetition. |
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| * Factoring out repetition with templates (cont.) |
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| We can define a new template: |
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| .code state-of-go/template/define.go /define "list"/,/^{{end}}/ |
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| And use it where needed: |
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| .code state-of-go/template/define.go /define "presentation"/,/^{{end}}/ |
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| * Factoring out repetition with templates (cont.) |
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| We can parse that template and execute it. |
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| .play state-of-go/template/define.go /func main/,/^}/ |
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| * Template redefinition |
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| We made also our template easier to reuse, as we can redefine `list`. |
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| .play state-of-go/template/redefine.go /func main/,/^}/ |
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| * Meet the block action |
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| The `block` action defines and executes a template in place. |
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| .code state-of-go/template/blocks.go /define/,/`/ |
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| That template defined by `block` can be: |
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| - referenced later by the same template, |
| - redefined with `define`. |
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| * Why do we need it? |
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| It is more compact when |
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| - we're not factoring out repetition, |
| - but we need to provide an extension point. |
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| We can make the following template more compact with `block`. |
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| {{define "content" .}} |
| <h1>{{.Heading}}<h1> |
| <p>{{.Content}}</p> |
| {{end}} |
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| {{define "page"}} |
| <title>{{.Title}}</title> |
| <body> |
| {{template "content" .}} |
| </body> |
| {{end}} |
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| * Why do we need it? (cont.) |
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| We can make the following template more compact with `block`. |
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| {{define "page"}} |
| <title>{{.Title}}</title> |
| <body> |
| {{block "content" .}} |
| <h1>{{.Heading}}<h1> |
| <p>{{.Content}}</p> |
| {{end}} |
| </body> |
| {{end}} |
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| And still easily redefine `content`. |
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| * sort.Sort is faster |
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| `Sort` sorts your data by calling `Less`, `Swap`, and `Len`. |
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| We reduced the number of comparisons and swaps by about 10%. |
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| Sort `[]int` with Go 1.5 |
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| BenchmarkSort_1-4 20000000 67.2 ns/op |
| BenchmarkSort_10-4 10000000 227 ns/op |
| BenchmarkSort_100-4 500000 3863 ns/op |
| BenchmarkSort_1000-4 30000 52189 ns/op |
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| Sort `[]int` with Go 1.6 |
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| BenchmarkSort_1-4 20000000 64.7 ns/op |
| BenchmarkSort_10-4 10000000 137 ns/op |
| BenchmarkSort_100-4 500000 2849 ns/op |
| BenchmarkSort_1000-4 30000 46949 ns/op |
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| * sort.Sort is faster - plot |
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| .image state-of-go/img/bench-sort.png _ 800 |
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| * Sort order and sort.Stable |
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| Reminder: sort.Sort is not a _stable_ sort. |
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| .play state-of-go/sort/unstable.go /byLength/, |
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| Use `sort.Stable`: |
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| .play state-of-go/sort/stable.go /func main/, |
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| * Minor changes |
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| .image state-of-go/img/minorchanges.png _ 900 |
| .caption too many to discuss: find them [[https://golang.org/doc/go1.6#minor_library_changes][here]] |
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| * Let's just discuss one |
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| `time.Parse` is smarter! |
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| .play state-of-go/time/time.go /func main/,/^}/ |
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| * Changes to the runtime |
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| * Detection of concurrent map accesses |
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| Detection of unsafe concurrent access to maps. |
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| .play state-of-go/runtime/crash.go /const/,/Wait\(\)/ |
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| Outputs: |
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| fatal error: concurrent map read and map write |
| fatal error: concurrent map writes |
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| * Does it make it slower? |
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| No! |
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| Let's benchmark it - with a correct solution. |
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| .code state-of-go/runtime/good/good.go /func count/,/^}/ |
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| * Benchmark results |
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| Go 1.4 - GOMAXPROCS = 4 |
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| BenchmarkCount_1 1000000 1862 ns/op |
| BenchmarkCount_10 100000 21214 ns/op |
| BenchmarkCount_100 1000 1602507 ns/op |
| BenchmarkCount_1000 10 141712948 ns/op |
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| Go 1.5 - GOMAXPROCS = 4 |
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| BenchmarkCount_1-4 2000000 867 ns/op |
| BenchmarkCount_10-4 200000 6909 ns/op |
| BenchmarkCount_100-4 1000 1025092 ns/op |
| BenchmarkCount_1000-4 20 94093719 ns/op |
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| Go 1.6 - GOMAXPROCS = 4 |
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| BenchmarkCount_1-4 2000000 750 ns/op |
| BenchmarkCount_10-4 200000 6582 ns/op |
| BenchmarkCount_100-4 2000 1113790 ns/op |
| BenchmarkCount_1000-4 20 87998054 ns/op |
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| * Benchmark results plot |
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| .image state-of-go/img/bench4.png _ 800 |
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| * Benchmark results |
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| Go 1.4 - GOMAXPROCS = 1 |
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| BenchmarkCount_1 100000 1370 ns/op |
| BenchmarkCount_10 20000 8622 ns/op |
| BenchmarkCount_100 500 362725 ns/op |
| BenchmarkCount_1000 50 31378803 ns/op |
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| Go 1.5 - GOMAXPROCS = 1 |
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| BenchmarkCount_1-4 2000000 776 ns/op |
| BenchmarkCount_10-4 200000 6288 ns/op |
| BenchmarkCount_100-4 3000 345037 ns/op |
| BenchmarkCount_1000-4 50 31751625 ns/op |
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| Go 1.6 - GOMAXPROCS = 1 |
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| BenchmarkCount_1-4 2000000 767 ns/op |
| BenchmarkCount_10-4 200000 6041 ns/op |
| BenchmarkCount_100-4 5000 329328 ns/op |
| BenchmarkCount_1000-4 50 30176034 ns/op |
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| * Benchmark results plot |
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| .image state-of-go/img/bench1.png _ 800 |
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| * Garbage Collector in Go 1.5 |
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| At [[https://www.youtube.com/watch?v=aiv1JOfMjm0][GopherCon 2015 Rick Hudson gave a presentation]] about the Go 1.5 low latency collector |
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| .image state-of-go/img/gc345.png 500 _ |
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| * Garbage Collector in Go 1.6 |
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| At [[http://www.infoq.com/presentations/go-gc-performance][QCon SF in November Rick Hudson]] gave an updated presentation which showed this comparison of Go 1.5 to the upcoming Go 1.6 |
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| .image state-of-go/img/gc56.png 400 _ |
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| _Yes,_that_is_gigabytes_on_the_X_axis_ |
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| * Garbage Collector on tip |
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| Right now it's even better! |
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| .image state-of-go/img/gcgotip.png _ 600 |
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| * People loved it with Go 1.5 |
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| .image state-of-go/img/twitter1.png _ 550 |
| .caption [[https://twitter.com/brianhatfield/status/634166123605331968][original tweet]] |
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| * People love it even more with Go 1.6 |
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| .image state-of-go/img/twitter2.png _ 600 |
| .caption [[https://twitter.com/brianhatfield/status/692778741567721473][original tweet]] |
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| * Oops |
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| .image state-of-go/img/twitter3.png _ 600 |
| .caption [[https://twitter.com/bradfitz/status/692787593558118400][original tweet]] and [[https://www.youtube.com/watch?v=CduA0TULnow&t=1m29s][video]] |
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| * New ports |
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| Experimental ports to Linux on 64-bit MIPS (linux/mips64 and linux/mips64le). |
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| Experimental port to Android on 32-bit x86 (android/386). |
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| On Linux on little-endian 64-bit PowerPC (linux/ppc64le), Go 1.6 now supports cgo with external linking and is roughly feature complete. |
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| On NaCl, Go 1.5 required SDK version pepper-41. Go 1.6 adds support for later SDK versions. |
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| * Changes to the tooling |
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| * The cgo tool |
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| Go is garbage collected, can C and Go share memory? |
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| In short: |
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| - Go can pass a pointer to C |
| - the referenced memory can't have pointers to Go allocated memory |
| - C can't keep pointers to the memory after the call returns |
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| In more detail: |
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| - the `cgo` [[https://tip.golang.org/cmd/cgo/#hdr-Passing_pointers][docs]]. |
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| This is checked by the runtime at execution. |
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| You could disable the checks, but you probably shouldn't. |
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| * Sharing pointers between Go and C |
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| .code state-of-go/cgo/main.go |
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| Outputs: |
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| panic: runtime error: cgo argument has Go pointer to Go pointer |
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| * The go tool |
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| GO15VENDOREXPERIMENT is now enabled by default. |
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| How does it work? |
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| /home/user/gocode/ |
| src/ |
| server-one/ |
| main.go (import "github.com/gorilla/mux") |
| server-two/ |
| main.go (import "github.com/gorilla/mux") |
| vendor/ |
| github.com/ |
| gorilla/ |
| mux/ |
| ... |
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| `server-one` uses the `mux` package in `$GOPATH/src/github.com/gorilla/mux`. |
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| `server-two` uses the `mux` package in `vendor`. |
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| * Vendoring demo |
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| * go doc |
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| Go 1.5 added the possibility of searching by name |
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| go doc math Pi |
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| Go 1.6 defines priority of packages with import paths with less elements. |
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| Non vendored packages appear first. |
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| * go vet |
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| Go vet warns if the code prints a function instead of its result. |
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| .play state-of-go/govet/main.go |
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| `go`vet` output: |
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| main.go:8: arg foo in Println call is a function value, not a function call |
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| The warning can be removed using `%p` in the format string. |
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| * The community |
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| * The community |
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| Code of Conduct announced on November 24th 2015 |
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| Go meetups: |
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| - [[http://go-meetups.appspot.com]] |
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| Women Who Go - 7 chapters already! |
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| - [[http://www.womenwhogo.org]] |
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| * Conferences: |
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| - [[http://gophergala.com/][GopherGala]] Jan 22-24th (judging proposals now) |
| - [[https://fosdem.org/2016/][FOSDEM]] Right here, right now. Hello! |
| - [[http://gophercon.ae][GopherCon Dubai]], Feb 23rd |
| - [[http://www.gophercon.in/][GopherCon India]], Feb 19-20th |
| - [[https://gophercon.com/][Gophercon Denver]], Jul 11-13th |
| - [[http://2016.dotgo.eu/][dotGo]], Nov 9th |
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| * Go 1.6 release party, February 17th |
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| Go 1.6 ships soon! |
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| Go meetups are organising to hold a [[https://github.com/golang/go/wiki/Go-1.6-release-party][release party]] on the 17th of February. |
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| .image state-of-go/img/party-gopher.png _ 300 |
| .caption Join the party!!! |