Fix mango tests using custom db name

[jiahuili430]

Overview

When running mango tests, sometimes get
org.apache.lucene.store.NoSuchDirectoryException error. This is because each test in the same class used the same database name, and in the setUp function always delete and recreate it, which caused a race condition.

Using custom database names should solve it.

Testing recommendations

make mango-test

Related Issues or Pull Requests

Checklist

• Code is written and works correctly
• Changes are covered by tests
• Any new configurable parameters are documented in rel/overlay/etc/default.ini
• Documentation changes were made in the src/docs folder
• Documentation changes were backported (separated PR) to affected branches

[iilyak]

There are many tests files which use self.db.recreate() did you consider modifying that function?

[jiahuili430]

If using the same db name, 0.13 is the shortest time to avoid 500 locally.
This approach also increased the overall Mango test time to 60.730s, compared to 49.936s using custom database name.

def recreate(self):
-    NUM_TRIES = 10
+    NUM_TRIES = 3

-    for k in range(NUM_TRIES):
+    for k in range(1, NUM_TRIES):
         r = self.sess.get(self.url)
         if r.status_code == 200:
             db_info = r.json()
             docs = db_info["doc_count"] + db_info["doc_del_count"]
                 if docs == 0:
                     # db exists and it is empty -- exit condition is met
                     return
                 self.delete()
+        time.sleep(k * 0.13)
         self.create()
-        time.sleep(k * 0.1)
     raise Exception(
         "Failed to recreate the database after {} tries".format(NUM_TRIES)
     )

[jaydoane]

There was recent work done on the recreate function, but it didn't seem to address the raciness of reusing db names.

[jiahuili430]

Thank you for the link!