ef250e58dd
Load balancer aims to preserve a balance in rack loads when generating tablet migrations. However, this balance might get broken when dead nodes are present. Currently, these nodes aren't include in rack load calculations, even if they own tablet replicas. As a result, load balancer treats racks with dead nodes as racks with a lower load, so I generates migrations to these racks. This is incorrect, because a dead node might come back alive, which would result in having multiple tablet replicas on the same rack. It's also inefficient even if we know that the node won't come back - when it's being replaced or removed. In that case we know we are going to rebuild the lost tablet replicas so migrating tablets to this rack just doubles the work. Allowing such migrations to happen would also require adjustments in the materialized view pairing code because we'd temporarily allow having multiple tablet replicas on the same rack. So in this patch we include dead nodes when calculating rack loads in the load balancer. The dead nodes still aren't treated as potential migration sources or destinations. We also add a test which verifies that no migrations are performed by doing a node replace with a mv workload in parallel. Before the patch, we'd get pairing errors and after the patch, no pairing errors are detected. Fixes https://github.com/scylladb/scylladb/issues/24485 Closes scylladb/scylladb#26028
Scylla in-source tests.
For details on how to run the tests, see docs/dev/testing.md
Shared C++ utils, libraries are in lib/, for Python - pylib/
alternator - Python tests which connect to a single server and use the DynamoDB API unit, boost, raft - unit tests in C++ cqlpy - Python tests which connect to a single server and use CQL topology* - tests that set up clusters and add/remove nodes cql - approval tests that use CQL and pre-recorded output rest_api - tests for Scylla REST API Port 9000 scylla-gdb - tests for scylla-gdb.py helper script nodetool - tests for C++ implementation of nodetool
If you can use an existing folder, consider adding your test to it. New folders should be used for new large categories/subsystems, or when the test environment is significantly different from some existing suite, e.g. you plan to start scylladb with different configuration, and you intend to add many tests and would like them to reuse an existing Scylla cluster (clusters can be reused for tests within the same folder).
To add a new folder, create a new directory, and then
copy & edit its suite.ini.