How do you determine the true size impact of imported packages on a Go executable?

Assessing the Size of a Go Project

Measuring the size of a Go project can be beneficial for optimizing performance or monitoring resource utilization.

Checking Binary Size

To determine the size of the project's binaries, navigate to the $GOPATH/pkg directory, where $GOPATH represents the installed Go packages path. For example:

$ cd $GOPATH/pkg/darwin_amd64/github.com/gorilla/

Within this directory, execute the following command to display the binary sizes in kilobytes (KB):

$ du -k *

Considerations for Package Size

While the above method provides information about library binary sizes, it's crucial to note that the actual space occupied within the executable after linking may vary. This is due to package dependencies and the potential for shared dependencies between imported packages.

To illustrate this, consider the following example:

package main

import "net/http"

var _ = http.Serve

func main() {}

Compared to:

package main

import "github.com/gorilla/mux"

var _ = mux.NewRouter

func main() {}

Both programs execute zero user code, but their dependencies differ. The resulting binary sizes demonstrate the additional space required due to dependency inheritance:

$ du -k *

1028    empty  (no dependencies)
5812    http  (depends on net/http)
5832    mux  (depends on net/http, inherits extra baggage)

Conclusion

The Go linker effectively strips unnecessary baggage during the build process. However, to fully understand the impact of imported packages on the executable size, it's essential to consider their sub-dependencies as well. By examining both the package size and dependencies, developers can optimize their Go projects for performance and resource efficiency.

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