A 4 minutes speech about the low-level mechanisms of the Go language.

1. Seen by a C++ developer
The low-level awesomeness of
Go

2. Concurrent I/O programming in
C++

3. Concurrent I/O programming in
C++
Complicated: Program intent diluted
into synchronization tooling (threads,
mutexes, event loops).

4. Concurrent I/O programming in
C++
Verbose: A lot of code to write to do
simple things.

5. Concurrent I/O programming in
C++
Delicate: One step out of the way and
you blow the whole thing up.

6. Why Go appeals C++
developers

7. Why Go appeals C++
developers
Goroutines: Break the code into logical
parts

8. Why Go appeals C++
developers
I/O friendly: Netpoller frees the
developer from infamous callbacks

9. Why Go appeals C++
developers
Code as data flow: Channels makes it
easy to write application as a data
pipeline

10. Goroutines : how does it do it

11. Goroutines : how does it do it
Go is written in assembly and Go
exclusively (except for cgo).
ASM code

12. Goroutines : how does it do it
Jumping the execution flow between a
goroutine and the scheduler is fast
Fast context switching

13. Process/Thread 3000 to 4500 ns
CPU Affinity 1300 to 1900 ns
CPU
Affinity
Goroutine: < 10 ns
Goroutines : how does it do it
Fast context switching

14. Goroutines : how does it do it
TLS is used to jump from a Goroutine to the
scheduler
Classic TLS can be costly depending on the
platform
Thread Local Storage

15. Goroutines : how does it do it
Go takes advantage of a unused MMU
registry if possible
Thread Local Storage

16. Netpoller: how does it do it

17. Netpoller: how does it do it
The scheduler unparks Goroutines just
when I/O is available.
Hidden in the scheduler

18. Netpoller: how does it do it
epoll for Linux
kqueue for Mac OS
I/O Completion ports for Windows
Syscalls depending on the OS

19. Channels : how does it do it

20. Channels : how does it do it
Lock-free for a writer in a non-full channel.
Lock-free for a reader in a non-empty
channel.
Critical section stays short for blocking
calls.
Limited usage of mutexes

21. Channels : how does it do it
Lock-free operations use atomic
CopyAndSwap for modern processors
Atomics

22. Channels : how does it do it
Go mutexes are implemented with futexes
(Fast Userspace muTEX).
Fast mutexes

23. duckie.github.io/boson
See those things implemented
in C++

24. Thank you very much