What causes this race condition

[st ov]

I'm trying to understand what is causing this race condition.

From what I can tell, this function will behave as expected.

The assignment will eventually end the for loop and execute the print statement.

Yet go test -race will detect a race condition.

Does the presence of any concurrent unprotected read trigger a data race, disregarding the logic as a whole?

  package main
  
  import (  
      "fmt"
      "runtime"
  )

  func main() {  
      done := false
  
      go func(){
          done = true
      }()
  
      for !done {
          runtime.Gosched()
      }
      fmt.Println("done!")
  }

  $ go run -race racy.go
  ==================
  WARNING: DATA RACE
  Write at 0x00c42009800f by goroutine 6:
    main.main.func1()
        /home/eric/racy.go:12 +0x38
  
  Previous read at 0x00c42009800f by main goroutine:
    main.main()
        /home/eric/racy.go:15 +0x8b
  
  Goroutine 6 (running) created at:
    main.main()
        /home/eric/racy.go:11 +0x76
  ==================
  done!
  Found 1 data race(s)
  exit status 66

[Dave Cheney]

I recommend this, https://golang.org/doc/articles/race_detector.html

Specifically to your question, “ A data race occurs when two goroutines access the same variable concurrently and at least one of the accesses is a write. ”

[st ov]

Thanks Dave, that answers my question.