如何减少已编译文件的大小？

Note: This answer is outdated

Please note that this answer is outdated. Please refer to the other higher-voted answers. I would like to delete this post, accepted answers can't be deleted though.

Is it a problem that the file is larger? I don't know Go but I would assume that it statically links some runtime lib which is not the case for the C program. But probably that is nothing to worry about as soon as your program gets larger.

As described here, statically linking the Go runtime is the default. That page also tells you how to set up for dynamic linking.

Go binaries are large because they are statically linked (except for library bindings using cgo). Try statically linking a C program and you'll see it grow to a comparable size.

If this is really a problem for you (which I have a hard time believing), you can compile with gccgo and dynamically link.

More compact hello-world example:

package main


func main() {
print("Hello world!")
}

We are skiped large fmt package and noticeably reduced binary:

  $ go build hello.go
$ ls -lh hello
... 259K ... hello2
$ strip hello
$ ls -lh hello
... 162K ... hello2

Not so compact as C, but though measured in K not M :) Ok, it is not general way just shows some ways to optimize a size: use strip and try to use minimum packages. Anyway Go is not language for making tiny sized binaries.

The binary contains by default the garbage collector, the schedulding system that manage the go routines, and all the libraries you import.

The result is a minimal size of about 1 Mb.

If you are using a Unix-based system (e.g. Linux or Mac OSX) you could try removing the debugging information included in the executable by building it with the -w flag:

go build -ldflags "-w" prog.go

The file sizes are reduced dramatically.

For more details visit the GDB's page: http://golang.org/doc/gdb

You should get goupx, it will "fix" Golang ELF executables to work with upx. I've already got around 78% file size shrink in some cases ~16MB >> ~3MB.

Compression ratio usually tends to 25%, so it's worth a try:

$ go get github.com/pwaller/goupx
$ go build -o filename
$ goupx filename

>>

2014/12/25 10:10:54 File fixed!


File size         Ratio      Format      Name
--------------------   ------   -----------   -----------
16271132 ->   3647116   22.41%  linux/ElfAMD   filename


Packed 1 file.

EXTRA: -s flag (strip) can shrink bin file even more goupx -s filename

The 2016 answer:

1. Use Go 1.7

2. Compile with go build -ldflags "-s -w"

➜ ls -lh hello
-rwxr-xr-x 1 oneofone oneofone 976K May 26 20:49 hello*

3. Then use upx, goupx is no longer needed since 1.6.

➜ ls -lh hello
-rwxr-xr-x 1 oneofone oneofone 367K May 26 20:49 hello*

From Go 1.8 you can also use the new plugin system to split up your binary into something that resembles shared libraries. For this release it only works on Linux, but other platforms will probably be supported in the future.

https://tip.golang.org/pkg/plugin/

create a file named main.go, let's try with simple hello world program.

package main


import "fmt"


func main(){
fmt.Println("Hello World!")
}

I use go version 1.9.1

$ go version
go version go1.9.1 linux/amd64

Compile with standard go build command.

$ go build main.go
$ ls -lh
-rwxr-xr-x-x 1 nil nil 1.8M Oct 27 07:47 main

Let's compile once again with go build but with ldflags as suggested above,

$ go build -ldflags "-s -w" main.go
$ ls -lh
-rwxr-xr-x-x 1 nil nil 1.2M Oct 27 08:15 main

File size is reduced by 30%.

Now, lets use gccgo,

$ go version
go version go1.8.1 gccgo (GCC) 7.2.0 linux/amd64

Building go with gccgo,

$ go build main.go
$ ls -lh
-rwxr-xr-x 1 nil nil 34K Oct 27 12:18 main

Binary size is reduced by almost 100%. Let's once again try building our main.go with gccgo but with build flags,

$ go build -gccgoflags "-s -w" main.go
-rwxr-xr-x 1 nil nil 23K Oct 27 13:02 main

As gccgo binaries were dynamically linked. If you have a binary which is very big in size, your binary when compiled with gccgo will not be decreased by 100%, but it will be reduced in size by considerable amount.