do not sleep to kill a process that has already cleaned up and exited by itself

runner/util_linux.go

@@ -1,6 +1,8 @@
 package runner
 
 import (
+	"context"
+	"errors"
 	"io"
 	"os/exec"
 	"syscall"
@@ -12,20 +14,65 @@ import (
 func (e *Engine) killCmd(cmd *exec.Cmd) (pid int, err error) {
 	pid = cmd.Process.Pid
 
+	var killDelay time.Duration
+
+	waitResult := make(chan error)
+	go func() {
+		defer close(waitResult)
+		_, _ = cmd.Process.Wait()
+	}()
+
 	if e.config.Build.SendInterrupt {
-		// Sending a signal to make it clear to the process that it is time to turn off
+		e.mainDebug("sending interrupt to process %d", pid)
+		// Sending a signal to make it clear to the process group that it is time to turn off
 		if err = syscall.Kill(-pid, syscall.SIGINT); err != nil {
 			return
 		}
-		time.Sleep(e.config.killDelay())
+		// the kill delay is 0 by default unless the user has configured send_interrupt=true
+		// in which case it is fetched from the kill_delay setting in the .air.toml
+		killDelay = e.config.killDelay()
+		e.mainDebug("setting a kill timer for %s", killDelay.String())
 	}
 
-	// https://stackoverflow.com/questions/22470193/why-wont-go-kill-a-child-process-correctly
-	err = syscall.Kill(-pid, syscall.SIGKILL)
+	// prepare a cancel context that can stop the killing if it is not needed
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	killResult := make(chan error)
+	// Spawn a goroutine that will kill the process after kill delay if we have not
+	// received a wait result before that.
+	go func() {
+		select {
+		case <-time.After(killDelay):
+			e.mainDebug("kill timer expired")
+			// https://stackoverflow.com/questions/22470193/why-wont-go-kill-a-child-process-correctly
+			killResult <- syscall.Kill(-pid, syscall.SIGKILL)
+		case <-ctx.Done():
+			e.mainDebug("kill timer canceled")
+			return
+		}
+	}()
+
+	results := make([]error, 0, 2)
 
-	// Wait releases any resources associated with the Process.
-	_, _ = cmd.Process.Wait()
-	return
+	for {
+		// collect the responses from the kill and wait goroutines
+		select {
+		case err = <-killResult:
+			results = append(results, err)
+		case err = <-waitResult:
+			results = append(results, err)
+			// if we have a kill delay, we ignore the kill result
+			if killDelay > 0 && len(results) == 1 {
+				results = append(results, nil)
+			}
+		}
+
+		if len(results) == 2 {
+			err = errors.Join(results...)
+			return
+		}
+	}
 }
 
 func (e *Engine) startCmd(cmd string) (*exec.Cmd, io.ReadCloser, io.ReadCloser, error) {

runner/util_test.go

@@ -1,7 +1,6 @@
 package runner
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"os/exec"
@@ -10,7 +9,6 @@ import (
 	"runtime"
 	"strconv"
 	"strings"
-	"syscall"
 	"testing"
 	"time"
 
@@ -148,27 +146,6 @@ func TestAdaptToVariousPlatforms(t *testing.T) {
 	}
 }
 
-func Test_killCmd_no_process(t *testing.T) {
-	e := Engine{
-		config: &Config{
-			Build: cfgBuild{
-				SendInterrupt: false,
-			},
-		},
-	}
-	_, err := e.killCmd(&exec.Cmd{
-		Process: &os.Process{
-			Pid: 9999,
-		},
-	})
-	if err == nil {
-		t.Errorf("expected error but got none")
-	}
-	if !errors.Is(err, syscall.ESRCH) {
-		t.Errorf("expected '%s' but got '%s'", syscall.ESRCH, errors.Unwrap(err))
-	}
-}
-
 func Test_killCmd_SendInterrupt_false(t *testing.T) {
 	_, b, _, _ := runtime.Caller(0)
 

runner/util_unix.go

@@ -3,6 +3,8 @@
 package runner
 
 import (
+	"context"
+	"errors"
 	"io"
 	"os"
 	"os/exec"
@@ -13,18 +15,65 @@ import (
 func (e *Engine) killCmd(cmd *exec.Cmd) (pid int, err error) {
 	pid = cmd.Process.Pid
 
+	var killDelay time.Duration
+
+	waitResult := make(chan error)
+	go func() {
+		defer close(waitResult)
+		_, _ = cmd.Process.Wait()
+	}()
+
 	if e.config.Build.SendInterrupt {
-		// Sending a signal to make it clear to the process that it is time to turn off
+		e.mainDebug("sending interrupt to process %d", pid)
+		// Sending a signal to make it clear to the process group that it is time to turn off
 		if err = syscall.Kill(-pid, syscall.SIGINT); err != nil {
 			return
 		}
-		time.Sleep(e.config.killDelay())
+		// the kill delay is 0 by default unless the user has configured send_interrupt=true
+		// in which case it is fetched from the kill_delay setting in the .air.toml
+		killDelay = e.config.killDelay()
+		e.mainDebug("setting a kill timer for %s", killDelay.String())
+	}
+
+	// prepare a cancel context that can stop the killing if it is not needed
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	killResult := make(chan error)
+	// Spawn a goroutine that will kill the process after kill delay if we have not
+	// received a wait result before that.
+	go func() {
+		select {
+		case <-time.After(killDelay):
+			e.mainDebug("kill timer expired")
+			// https://stackoverflow.com/questions/22470193/why-wont-go-kill-a-child-process-correctly
+			killResult <- syscall.Kill(-pid, syscall.SIGKILL)
+		case <-ctx.Done():
+			e.mainDebug("kill timer canceled")
+			return
+		}
+	}()
+
+	results := make([]error, 0, 2)
+
+	for {
+		// collect the responses from the kill and wait goroutines
+		select {
+		case err = <-killResult:
+			results = append(results, err)
+		case err = <-waitResult:
+			results = append(results, err)
+			// if we have a kill delay, we ignore the kill result
+			if killDelay > 0 && len(results) == 1 {
+				results = append(results, nil)
+			}
+		}
+
+		if len(results) == 2 {
+			err = errors.Join(results...)
+			return
+		}
 	}
-	// https://stackoverflow.com/questions/22470193/why-wont-go-kill-a-child-process-correctly
-	err = syscall.Kill(-pid, syscall.SIGKILL)
-	// Wait releases any resources associated with the Process.
-	_, _ = cmd.Process.Wait()
-	return pid, err
 }
 
 func (e *Engine) startCmd(cmd string) (*exec.Cmd, io.ReadCloser, io.ReadCloser, error) {