cgo: processes started from exported function are not scheduled correctly. #1560
Description
Unpack the attached archive and run gotest.
I would expect the output to be around 1000, as both
sleeps should sleep concurrently.
Instead it prints around 2000 for me - the sleeps execute
sequentially.
If GOMAXPROCS > 0, it works as expected.
6g macos d9ff478c4ed3+ tip
Here is the salient code from the archive:
package tst
//#include <unistd.h>
// extern void BackgroundSleep(int);
// void twoSleeps(int n){
// BackgroundSleep(n);
// sleep(n);
// }
import "C"
var sleepDone = make(chan bool)
func ParSleep(n int){
C.twoSleeps(C.int(n))
<-sleepDone
}
//export BackgroundSleep
func BackgroundSleep(n int){
// This function should start running immediately,
// but it actually starts after twoSleeps has returned.
go func(){
C.sleep(C.uint(n))
sleepDone <- true
}()
}
func TestParSleep(t *testing.T) {
t0 := time.Nanoseconds()
ParSleep(1)
fmt.Printf("%d\n", (time.Nanoseconds() - t0) / 1e6)
}
Attachments:
- tstcgo.tgz (659 bytes)