In the case of high performance IO, where probably most strings are converted,
you use a ByteBuffer to avoid many small kernel calls anyway, and these can
copy the string data (WriteString) to the buffer directly without an
intermediate allocation.
> On Jul 5, 2019, at 7:00 AM, Slawomir Pryczek <slawek1...@gmail.com> wrote:
>
> Not sure if that's a good idea. Strings are immutable so you can pass string
> to function by reference, in thread safe manner. So if you pass same string
> to 2 threads and one of them modify it - you'll really have
> allocate+copy+modify so you're never touching the original thing so you can't
> have a race.
>
> Now if go introduced readolny []byte, we'd probably want to change all io
> functions to use that... and this would create a lot of confusion, because
> it'd be required to cast []byte to readonly version. And this casted variable
> wouldn't be readonly nor thread-safe at all, because underlying memory could
> still be changed using the original slice. So we'd need allocate+memcopy for
> readonly cast to do a network write.
>
> Or maybe there could be readonly []byte version for each io op. But it'd
> result only in many unnecessary OS calls.
>
> So what is needed in this case (i guess) is a reusable buffer anyway, and
> then you can do a copy to a byte buffer without a cast and allocation
> tstr := "abc"
> t := make([]byte, 10, 10)
> copy(t, tstr)
>
> W dniu piątek, 5 lipca 2019 04:27:58 UTC+2 użytkownik Ally Dale napisał:
>>
>> []byte is mutable in Go, but string is readonly, so []byte(string) in Go is
>> actually allocate&memcopy, and this operation is costly.
>> Sometimes, we need a readonly []byte parameter but we have string only, and
>> we have no choice but allocate&memcopy to make a new []byte variable from
>> string.
>> Eg: net.Send([]byte("ping")) is costly, but net.Send(readonly
>> []byte("ping")) can be cheaply.
>
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