Add test for global overcommit tracker

tests/integration/test_global_overcommit_tracker/configs/config.xml

@@ -0,0 +1,3 @@
+<clickhouse>
+    <max_server_memory_usage>5000000</max_server_memory_usage>
+</clickhouse>

tests/integration/test_global_overcommit_tracker/test.py

@@ -0,0 +1,43 @@
+import pytest
+
+from helpers.cluster import ClickHouseCluster
+
+cluster = ClickHouseCluster(__file__)
+
+node = cluster.add_instance('node', main_configs=['configs/config.xml'])
+
+@pytest.fixture(scope='module', autouse=True)
+def start_cluster():
+    try:
+        cluster.start()
+        yield cluster
+    finally:
+        cluster.shutdown()
+
+TEST_QUERY_A = 'SELECT number FROM numbers(130000) GROUP BY number SETTINGS max_guaranteed_memory_usage_for_user=1,memory_usage_overcommit_max_wait_microseconds=500'
+TEST_QUERY_B = 'SELECT number FROM numbers(130000) GROUP BY number SETTINGS max_guaranteed_memory_usage_for_user=2,memory_usage_overcommit_max_wait_microseconds=500'
+
+def test_overcommited_is_killed():
+    node.query("CREATE USER A")
+    node.query("GRANT ALL ON *.* TO A")
+    node.query("CREATE USER B")
+    node.query("GRANT ALL ON *.* TO B")
+
+    responses_A = list()
+    responses_B = list()
+    for _ in range(100):
+        responses_A.append(node.get_query_request(TEST_QUERY_A, user="A"))
+        responses_B.append(node.get_query_request(TEST_QUERY_B, user="B"))
+
+    overcommited_killed = False
+    for response in responses_A:
+        err = response.get_error()
+        if "MEMORY_LIMIT_EXCEEDED" in err:
+            overcommited_killed = True
+    for response in responses_B:
+        response.get_answer_and_error()
+
+    assert overcommited_killed, "no overcommited task was killed"
+
+    node.query("DROP USER IF EXISTS A")
+    node.query("DROP USER IF EXISTS B")