mysqlctl: Error out on stale socket (#14650)

Signed-off-by: Dirkjan Bussink <[email protected]>

go/vt/mysqlctl/mysqld.go

@@ -461,13 +461,13 @@ func cleanupLockfile(socket string, ts string) error {
 	if err == nil {
 		// If the process still exists, it's not safe to
 		// remove the lock file, so we have to keep it around.
-		log.Warningf("%v: not removing socket lock file: %v", ts, lockPath)
-		return nil
+		log.Errorf("%v: not removing socket lock file: %v with pid %v", ts, lockPath, p)
+		return fmt.Errorf("process %v is still running", p)
 	}
 	if !errors.Is(err, os.ErrProcessDone) {
 		// Any errors except for the process being done
 		// is unexpected here.
-		log.Errorf("%v: error checking process: %v", ts, err)
+		log.Errorf("%v: error checking process %v: %v", ts, p, err)
 		return err
 	}
 

go/vt/mysqlctl/mysqld_test.go

@@ -195,6 +195,6 @@ func TestCleanupLockfile(t *testing.T) {
 
 	// If the lockfile exists, and the process is found, we don't clean it up.
 	os.WriteFile("mysql.sock.lock", []byte(strconv.Itoa(os.Getpid())), 0o600)
-	assert.NoError(t, cleanupLockfile("mysql.sock", ts))
+	assert.Error(t, cleanupLockfile("mysql.sock", ts))
 	assert.FileExists(t, "mysql.sock.lock")
 }