golang：字节数组的gzip或zlib压缩偶尔会挂起

I have the following function to compress a byte array:

func compress(input []byte) []byte {
        var buf bytes.Buffer
        compr := gzip.NewWriter(&buf)
        compr.Write(input) // here it appears to hang until
                           // Enter is pressed
        compr.Close()
        output := buf.Bytes()

        return output
}

Sporadically the function will hang. When I press [Enter] the function will continue and return the expected result. Am I missing something here?

It will hang about one times out of five, even when the same input is given. Whether I use gzip or zlib, it doesn't matter.

I am using go 1.6 on Linux x86_64