test: add test_multiprocess_resource_limits to test memory limit sharing

This test ensures that spawned child processes inherit the same resource group as the parent by spawning 2 child processes which each allocate a 40MB object, it then verifies that one of the child processes was killed with SIGKILL for violating the resource quota.

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/test_nsjail.py b/tests/test_nsjail.py
index ec5c56f..c0ed96b 100644
--- a/tests/test_nsjail.py
+++ b/tests/test_nsjail.py
@@ -67,6 +67,34 @@ class NsJailTests(unittest.TestCase):
         self.assertIn("Resource temporarily unavailable", result.stdout)
         self.assertEqual(result.stderr, None)
 
+    def test_multiprocess_resource_limits(self):
+        code = dedent("""
+            import time
+            from multiprocessing import Process
+
+            def f():
+                object = "A" * 40_000_000
+                time.sleep(0.5)
+
+
+            proc_1 = Process(target=f)
+            proc_2 = Process(target=f)
+
+            proc_1.start()
+            proc_2.start()
+
+            proc_1.join()
+            proc_2.join()
+
+            print(proc_1.exitcode, proc_2.exitcode)
+        """)
+
+        result = self.nsjail.python3(code)
+
+        exit_codes = result.stdout.strip().split()
+        self.assertIn("-9", exit_codes)
+        self.assertEqual(result.stderr, None)
+
     def test_read_only_file_system(self):
         for path in ("/", "/etc", "/lib", "/lib64", "/snekbox", "/usr"):
             with self.subTest(path=path):