exec/linux: move Limit to after Start

client/driver/exec.go

@@ -52,15 +52,16 @@ func (d *ExecDriver) Start(ctx *ExecContext, task *structs.Task) (DriverHandle,
 
 	// Setup the command
 	cmd := executor.Command(command, args...)
-	err := cmd.Limit(task.Resources)
-	if err != nil {
-		return nil, fmt.Errorf("failed to constrain resources: %s", err)
-	}
-	err = cmd.Start()
+	err := cmd.Start()
 	if err != nil {
 		return nil, fmt.Errorf("failed to start command: %v", err)
 	}
 
+	err = cmd.Limit(task.Resources)
+	if err != nil {
+		return nil, fmt.Errorf("failed to constrain resources: %s", err)
+	}
+
 	// Return a driver handle
 	h := &execHandle{
 		cmd:    cmd,

client/executor/exec_linux.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"os/user"
+	"strconv"
 	"syscall"
 
 	"github.com/hashicorp/go-multierror"