[KAFKA-1954] Speed Up The Unit Tests

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Labels: newbie++
• Assignee: Balint Molnar
• Reporter: Jay Kreps
• Created: 14/Feb/15 19:43
• Updated: 03/Mar/18 06:21

Description

The server unit tests are pretty slow. They take about 8m40s on my machine. Combined with slow scala compile time this is kind of painful.

Almost all of this time comes from the integration tests which start one or more brokers and then shut them down.

Our finding has been that these integration tests are actually quite useful so we probably can't just get rid of them.

Here are some times:
Zk startup: 100ms
Kafka server startup: 600ms
Kafka server shutdown: 500ms

So you can see that an integration test suite with 10 tests that starts and stops a 3 node cluster for each test will take ~34 seconds even if the tests themselves are instantaneous.

I think the best solution to this is to get the test harness classes in shape and then performance tune them a bit as this would potentially speed everything up. There are several test harness classes:

• ZooKeeperTestHarness
• KafkaServerTestHarness
• ProducerConsumerTestHarness
• IntegrationTestHarness (similar to ProducerConsumerTestHarness but using new clients)

Unfortunately often tests don't use the right harness, they often use a lower-level harness than they should and manually create stuff. Usually the cause of this is that the harness is missing some feature.

I think the right thing to do here is
1. Get the tests converted to the best possible harness. If you are testing producers and consumers then you should use the harness that creates all that and shuts it down for you.
2. Optimize the harnesses to be faster.

How can we optimize the harnesses? I'm not sure, I would solicit ideas. Here are a few:
1. It's worth analyzing the logging to see what is taking up time in the startup and shutdown.
2. There may be things like controlled shutdown that we can disable (since we are anyway going to discard the brokers after shutdown.
3. The harnesses could probably start all the servers and all the clients in parallel.
4. We maybe able to tune down the resource usage in the server config for test cases a bit.

Issue Links

• is related to: KAFKA-1402 Create unit test helper that stops and starts a cluster