Fix Single Threaded Client Usage Issues in Parallel ACL SETUSER Tests

[kevinmichaelbowersox]

Summary

The ParallelTests#ParallelAclSetUserTest and ParallelTests#ParallelAclSetUserAvoidsMapContentionTest have issues surrounding the client selected for the test and how the client is used within the test. This misuse can lead to sporadic thread safety and memory access violation issues when executing tests.

ParallelAclSetUserTest

The ParallelAclSetUserTest uses the single threaded GarnetClientSession, however it launches concurrent tasks using Task.WhenAll. This violates the contract of the single threaded client causing sporadic issues with the test. To fix this problem unnecessary usage of Task.WhenAll was removed and each individual async command executed by the client was awaited.

ParallelAclSetUserAvoidsMapContentionTest

The ParallelAclSetUserAvoidsMapContentionTest uses the single threaded GarnetClientSession to start many tasks concurrently using Task.WhenAll. The goal is to create a close race between the first successful task and the runner up, causing contention on the ACL map. However, it launches the concurrent tasks using Task.WhenAll, violating the contract of the ingle threaded client. To fix this problem, the test was updated to use the GarnetClient, which has support for multiple threads.

[badrishc]

If we want to create server side races, shouldn't we be using multiple GarnetClientSession (one GCS per parallel thread/task) instead of a shared GarnetClient? Because a single GarnetClient will linearize all the requests into a fifo stream on a single TCP connection at the server.

[kevinmichaelbowersox]

If we want to create server side races, shouldn't we be using multiple GarnetClientSession (one GCS per parallel thread/task) instead of a shared GarnetClient? Because a single GarnetClient will linearize all the requests into a fifo stream on a single TCP connection at the server.

Agree. Thanks for pointing this out. I switched back to using multiple clients and was able to create the race (testing with our fixes from the change that introduced the test removed).