Use emulated POSIX module backend in sandboxed mode

Author: fangerer

mx.graalpython/mx_graalpython.py

@@ -1514,14 +1514,14 @@ def _register_vms(namespace):
         '--experimental-options', '--engine.MultiTier=true',
     ]), SUITE, 10)
     python_vm_registry.add_vm(GraalPythonVm(config_name=CONFIGURATION_SANDBOXED, extra_polyglot_args=[
-        '--llvm.managed',
+        '--llvm.managed', '--python.PosixModuleBackend=java'
     ]), SUITE, 10)
     python_vm_registry.add_vm(GraalPythonVm(config_name=CONFIGURATION_NATIVE, extra_polyglot_args=[
     ]), SUITE, 10)
     python_vm_registry.add_vm(GraalPythonVm(config_name=CONFIGURATION_NATIVE_INTERPRETER, extra_polyglot_args=[
         '--experimental-options', '--engine.Compilation=false']), SUITE, 10)
     python_vm_registry.add_vm(GraalPythonVm(config_name=CONFIGURATION_SANDBOXED_MULTI, extra_polyglot_args=[
-        '--experimental-options', '-multi-context', '--llvm.managed',
+        '--experimental-options', '-multi-context', '--llvm.managed', '--python.PosixModuleBackend=java'
     ]), SUITE, 10)
     python_vm_registry.add_vm(GraalPythonVm(config_name=CONFIGURATION_NATIVE_MULTI, extra_polyglot_args=[
         '--experimental-options', '-multi-context',

mx.graalpython/mx_graalpython_benchmark.py

@@ -414,7 +414,9 @@ def __init__(self, config_name=CONFIGURATION_DEFAULT, distributions=None, cp_suf
                                             extra_polyglot_args=extra_polyglot_args, env=env)
 
     def launcher_class(self):
-        return 'com.oracle.graal.python.shell.GraalPythonMain'
+        # We need to do it lazily because 'mx_graalpython' is importing this module
+        from mx_graalpython import GRAALPYTHON_MAIN_CLASS
+        return GRAALPYTHON_MAIN_CLASS
 
     def run_in_graalvm(self, cwd, args, extra_polyglot_args, host_vm):
         with environ(self._env or {}):