Try to lower default parallelism

Author: msimacek

graalpython/com.oracle.graal.python.test/src/runner.py

@@ -744,7 +744,7 @@ def run_in_subprocess_and_watch(self):
                         cmd.append('--failfast')
                     self.process = subprocess.Popen(cmd, stdout=self.out_file, stderr=self.out_file)
 
-                    server.settimeout(300.0)
+                    server.settimeout(600.0)
                     with server.accept()[0] as sock:
                         conn = Connection(sock)
 

mx.graalpython/mx_graalpython.py

@@ -916,7 +916,7 @@ def run_python_unittests(python_binary, args=None, paths=None, exclude=None, env
         lock.acquire()
 
     if parallel is None:
-        parallel = 6 if paths is None else 1
+        parallel = 4 if paths is None else 1
 
     args = args or []
     args = [