alter stress: try to avoid running out of host disk space

alter/stress/tests/actions.py

@@ -503,12 +503,12 @@ def clear_random_column(self):
 @TestStep
 @Retry(timeout=step_retry_timeout, delay=step_retry_delay)
 @Name("delete row")
-def delete_random_rows(self):
+def delete_random_rows(self, table_name=None):
     """Delete a few rows at random."""
-    table_name = get_random_table_name()
+    table_name = table_name or get_random_table_name()
     node = get_random_node_for_table(table_name=table_name)
     column_name = get_random_column_name(node=node, table_name=table_name)
-    divisor = random.choice([5, 11, 17, 23])
+    divisor = random.choice([2, 3, 5])
     remainder = random.randint(0, divisor - 1)
 
     By(
@@ -534,7 +534,7 @@ def delete_random_rows_lightweight(self):
     table_name = get_random_table_name()
     node = get_random_node_for_table(table_name=table_name)
     column_name = get_random_column_name(node=node, table_name=table_name)
-    divisor = random.choice([5, 11, 17, 23])
+    divisor = random.choice([2, 3, 5])
     remainder = random.randint(0, divisor - 1)
 
     with By(f"delete rows from {table_name} with {node.name}"):

alter/stress/tests/stress_alter.py

@@ -265,7 +265,7 @@ def alter_combinations(
                         join()
 
                 finally:
-                    with Then("I make sure that the replicas are consistent", flags=TE):
+                    with Finally("I make sure that the replicas are consistent", flags=TE):
                         if kill_stuck_mutations:
                             with By("killing any failing mutations"):
                                 for node in self.context.ch_nodes:
@@ -285,6 +285,14 @@ def alter_combinations(
                                 restore_consistent_structure=enforce_table_structure
                             )
 
+                    with And("I make sure that there is still free disk space on the host"):
+                        r = self.context.cluster.command(None, "df -h .")
+                        if "100%" in r.output:
+                            with When("I drop rows to free up space"):
+                                for table_name in self.context.table_names:
+                                    delete_random_rows(table_name=table_name)
+                                    delete_random_rows(table_name=table_name)
+
             note(f"Average time per test combination {(time.time()-t)/(i+1):.1f}s")
 
     finally: