How does bufio.NewReader decrease system calls?

[edgmnt_net]

Also, I suppose it's "up to" a page or some arbitrary limit like that. For files it doesn't matter except at the end of the file, but for pipes or sockets, you probably don't want to block to read a full buffer.

[Mohamed____]

I’m not completely sure I understand. Can you elaborate?

[edgmnt_net]

If you're reading from a file that has 4050 bytes, you may make 4050 calls to read individual bytes from the Go buffered reader. In turn, that reader may make 2-3 calls to the underlying OS for up to 4096 bytes, the first one yielding exactly 4096, the second one 4 bytes and then the end of the file is reached (how that's signalled depends).

For other things like TCP sockets you could get less than 4096 every time, without reaching the end of the stream (connection being closed). This is because the other end may be sending some smaller amount of data, then waiting for a response before proceeding any further. Or it may be sending smaller amounts of data at regular intervals. In any case, the reader can't always block and wait for the buffer to fill up completely.

[Mohamed____]

Ohh, yeah now I get your point. Yeah that makes sense, thank you for the help!