Slides from the talk "Safe Go" at the Go West event "Going Electric and Autonomous @ Einride". https://www.meetup.com/sweden-go-west/events/289161938/

1. SAFE GO
GOTHENBURG, SWEDEN, OCT 26 2022
Max Ekman
Software Engineer
Einride

2. “Look ma! No hands!”
A Gopher in an autonomous vehicle? 01
The case for Safe Go
Unsafe code situations
Do’s and don’ts
Safe Go style guide
Questions?
02
03
04
05
06

3. A Gopher in an
autonomous
vehicle?
SECTION ONE

4. {
WHY A GOPHER THERE IN THE FIRST PLACE?
Simplicity.
Even “hard” AD
development
should be easy
to approach.
01. A GOPHER IN AN AUTONOMOUS VEHICLE

5. {
WHY A GOPHER THERE IN THE FIRST PLACE?
Commonality.
Engineers
should be able
to jump teams:
AD vs cloud.
01. A GOPHER IN AN AUTONOMOUS VEHICLE

6. {
WHY A GOPHER THERE IN THE FIRST PLACE?
Ecosystem.
Go has a huge open
source ecosystem.
Einride is part of it!
01. A GOPHER IN AN AUTONOMOUS VEHICLE

7. The case for
Safe Go
SECTION TWO

8. 03
Can Go be used in a
mixed criticality system?
CAN GO BE USED IN A SAFETY CRITICAL ENVIRONMENT?
02. THE CASE FOR SAFE GO
02

9. 03
We think yes!
But with the right
approach and tooling.
CAN GO BE USED IN A SAFETY CRITICAL ENVIRONMENT?
02. THE CASE FOR SAFE GO
02

10. Differences to “common” Go development
03. THE CASE FOR SAFE GO
● Long running processes - not req/resp
● Resource constrained environment
● “Soft” realtime requirements
● Debug challanges
● Requirements of high correctness

11. Unsafe code
situations
SECTION THREE

12. EXAMPLES OF UNSAFE CODE SITUATIONS
03. UNSAFE CODE SITUATIONS
🧮 Unbounded memory usage
🧠 Unbounded concurrency
⏱ Garbage collection latency
🔄 Synchronization and deadlocks

13. 🧮 UNBOUNDED MEMORY USAGE
03. UNSAFE CODE SITUATIONS
● Occurs when allocating during iterations:
loops, recursions, net RX etc
● Negatively impacts:
○ Resource usage
○ GC load
○ Heap fragmentation

14. 🧠 UNBOUNDED CONCURRENCY
03. UNSAFE CODE SITUATIONS
● Occurs when spawning goroutines during
iterations: loops, recursions, net RX etc
● Negatively impacts:
○ Runtime context switching
○ OS thread context switching
○ Goroutine heap allocations

15. ⏱ GARBAGE COLLECTION LATENCY
03. UNSAFE CODE SITUATIONS
● Occurs when there are many deallocations:
functions returns, variables out of scope etc
● Negatively impacts:
○ Time spent in runtime vs user code
○ CPU context switching waste

16. 🔄 SYNCHRONIZATION AND DEADLOCKS
03. UNSAFE CODE SITUATIONS
● Deadlocks can be a big problem when trying
to synchronize concurrent code
● Negatively impacts:
○ Less throughput
○ Leads to hard-to-find bugs

17. Do’s and
don’ts
SECTION FOUR

18. 🧮 UNBOUNDED MEMORY USAGE
04. DO’S AND DON’TS
Watch out for append() inside loops, especially when the input length is unknown
Don’t…

19. 🧮 UNBOUNDED MEMORY USAGE
04. DO’S AND DON’TS
Instead try to preallocate any slices to a given capacity
Do!

20. 🧠 UNBOUNDED CONCURRENCY
04. DO’S AND DON’TS
Don’t start goroutines in a loop without checking the length of the input
Don’t…

21. 🧠 UNBOUNDED CONCURRENCY
04. DO’S AND DON’TS
Instead spawn a known amount of “workers” and pass them the input.
Do! But use something
robust, like errgroup!

22. ⏱ GARBAGE COLLECTION LATENCY
04. DO’S AND DON’TS
Allocs can happen where you least expect it. Dig into the code to find out!
Don’t…

23. ⏱ GARBAGE COLLECTION LATENCY
04. DO’S AND DON’TS
In this case strings.Count() was enough, which doesn’t alloc anything.
Do!

24. 🔄 SYNCHRONIZATION AND DEADLOCKS
04. DO’S AND DON’TS
Watch out when getting access to references, mutexes doesn’t help here.
Don’t…

25. 🔄 SYNCHRONIZATION AND DEADLOCKS
04. DO’S AND DON’TS
Instead copy data inside locked section, if needed outside.
Do!

26. 🍑

27. ROB PIKE
Don't communicate by
sharing memory,
share memory by
communicating.
go-proverbs.github.io

28. Safe Go
style guide
and tooling
SECTION FIVE

29. 01
Watch this space!
einride.engineering/blog
github.com/einride
05. SAFE GO STYLE GUIDE
THE NEED FOR A STYLE GUIDE
05

30. Official docs rulez!
go.dev/doc/effective_go
go.dev/doc/gc-guide
go.dev/doc/diagnostics
Another good guide:
peter.bourgon.org/go-for-industrial-programming
OTHER RESOURCES

31. Questions?
And thanks!
SECTION SIX