[CASSANDRA-14078] Fix dTest test_bulk_round_trip_blogposts_with_max_connections

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Not A Problem
• Component/s: Test/dtest/python
• Labels: dtest
• Assignee: Jaydeepkumar Chovatia
• Reporter: Jaydeepkumar Chovatia

Authors

Jaydeepkumar Chovatia

• Created: 29/Nov/17 23:56
• Updated: 30/Jun/21 15:20
• Resolved: 30/Jun/21 15:20

Description

This ticket is regarding following dTest cqlsh_tests.cqlsh_copy_tests.CqlshCopyTest.test_bulk_round_trip_blogposts_with_max_connections

This test is trying to limit number of client connections and assumes that once connection count has reached then client will fail-over to other node and do the request. The reason is, it is not deterministic test case as it totally depends on what hardware you run, timing, etc.
For example
If we look at https://builds.apache.org/view/A-D/view/Cassandra/job/Cassandra-trunk-dtest/353/testReport/cqlsh_tests.cqlsh_copy_tests/CqlshCopyTest/test_bulk_round_trip_blogposts_with_max_connections/

...
Processed: 5000 rows; Rate: 2551 rows/s; Avg. rate: 2551 rows/s

All replicas busy, sleeping for 4 second(s)...
Processed: 10000 rows; Rate: 2328 rows/s; Avg. rate: 2307 rows/s

All replicas busy, sleeping for 1 second(s)...
Processed: 15000 rows; Rate: 2137 rows/s; Avg. rate: 2173 rows/s

All replicas busy, sleeping for 11 second(s)...
Processed: 20000 rows; Rate: 2138 rows/s; Avg. rate: 2164 rows/s

Processed: 25000 rows; Rate: 2403 rows/s; Avg. rate: 2249 rows/s

Processed: 30000 rows; Rate: 2582 rows/s; Avg. rate: 2321 rows/s

Processed: 35000 rows; Rate: 2835 rows/s; Avg. rate: 2406 rows/s

Processed: 40000 rows; Rate: 2867 rows/s; Avg. rate: 2458 rows/s

Processed: 45000 rows; Rate: 3163 rows/s; Avg. rate: 2540 rows/s

Processed: 50000 rows; Rate: 3200 rows/s; Avg. rate: 2596 rows/s

Processed: 50234 rows; Rate: 2032 rows/s; Avg. rate: 2572 rows/s

All replicas busy, sleeping for 23 second(s)...
Replicas too busy, given up
...

Here we can see request is timing out, sometimes it resumes after 1 second, next time 11 seconds and some times it doesn't work at all.

In my opinion this test is not a good fit for dTest as dTest(s) should be deterministic.