Go1.2 Introduction to new features

This is a creation in Article, where the information may have evolved or changed.

Go1.1.2 was officially released in 2013.08.12 for about 1 months.
The go language has entered the Go1.2 release process and is expected to be released by the end of 2013.

This article mainly lists some of the major improvements in Go1.2 and will continue to keep up to date.

Changes in language

Disable Nil object values

For Go1.0, the following code is available:

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1 2 3 4 5 6 7 8

type T struct { x [ ] 1 24 byte     Field int32 }func main() {     var x *T }

The operation x.Field will correspond to 1<<24 the memory of the location.
In Go1.2, this will cause panic or error.

Slice syntax increases the CAP field

Before slicing, the cap defaults to maximum.
Like what:

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1 2	10 int slice := array[2:4]

sliceThe capacity is 8. In Go1.2, if you want to have a capacity of 6, you can:

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1	slice = array[2:4:6]

If the start address of the first part is omitted, the default is 0.

With the customizable cap syntax, you can create your own new large memory and then construct the Malloc/free memory management function yourself.

The cap for slice returned by malloc is strictly limited to the size requested.

Design document for this syntax: https://docs.google.com/document/d/1GKKdiGYAghXRxC2BFrSEbHBZZgAGKQ-yXK-hRKBo0Kk/pub

CGO Support C + + source code

CGO supports function pointers, please refer to https://code.google.com/p/go/source/browse/misc/cgo/test/fpvar.gofor usage.

CGO supports C + + syntax, but only C-language import symbols are supported.

Added CPPFLAGS and parameter setting options for C + + CXXFLAGS .

More suitable for C-language export, but in C + + implementation of the library.

Note: The Windows version of MinGW also does not support external links, please refer to Issue6533for details.

Changes in runtime implementations

The function entry of Goroutines adopts preemptive scheduling.

In previous versions, if there was a dead loop inside the Goroutines,
Then other goroutines may not be able to get CPU resources for this thread.
Especially when the Gomaxprocs is set to 1 threads.

This problem is partially fixed in Go1.2: the Scheduler
The entrance is occasionally triggered. In other words, if any loop
A non-inline function is called internally, and the other Goroutines
There will also be an opportunity to execute on the same thread.

In Go1.2, the default stack size for Goroutine is temporarily changed from 4KB to 8KB.
The newly changed 8KB size can bring some performance gains for many practical applications.
Of course, a larger default stack also causes the program to use more memory.
Better stack technology is used to solve this problem in the subsequent go development.

At the same time the Goroutine stack has the maximum limit (not infinite), the 64-bit system default limit is 1GB,
The 32-bit system model is limited to 250MB.
If you need to adjust the default values, you can call runtime/debug the package's SetMaxStack function modifications.
For details, please refer to: CL12541052

The maximum number of system threads opened by the program has been increased (default is 10000).
If you need to adjust the default values, you can call runtime/debug the package's SetMaxThreads function modifications.
For details, please refer to: CL13037043

About Dynamic Library Support

External links are already supported in the Linux/arm version.
This is a key part of the Go compiler tool chain that supports dynamic library features.

The state of Gccgo

Expect the GCC4.9 to contain the complete Go1.2. The current GCC4.8.2 contains Go1.1.2.

Performance optimization

• Performance improvement of compress/bzip2:30%

• Crypto/des:5-fold Performance improvement

• Performance improvement for encoding/json:encoding 30%

• Net:windows/bsd Network and runtime deep integration (Linux/os X has been supported in Go1.1), 30% performance improvements

Changes to the standard library

The larger changes are:

• Encoding: A new package that provides a common encoding interface

• FMT: The introduction of parametric index support, mainly to deal with the change of parameter order after the translation of different languages

• Sync/atomic: Added a Swap function

• Text/template: Add eq / lt equal comparison functions, add {{else if ... }} simplified syntax

• Runtime: Limit the parameter SetFinalizer f type of the parameter, as long as you can assign a value

• Testing: Added TB interface

• image/gifAdded a encode function

• Md5/hash and other functions to increase convenience

New supported parameter index for FMT:

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1 2	"a" ' B ' ' C ' // output: c a a b

Simplified Hash Usage:

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1 2	hash: = SHA1. Sum ([] ( "123" fmt. Printf ( "H ( data) =%x\n "

Miscellaneous messages (Personal supplement)

• Go command line tool migrated to go.tools , and will greatly improve the layout

• go.text/encodingAdded support for GBK, completely solve the Chinese Windows command line Chinese garbled problem.

• go.imageAdded BMP storage and block TIFF read support, and currently does not support large TIFF images.

• notepad++ better highlighting, builtin function auto-completion, function/method list and other functions.