2dcd2b21ae
Fixes the following scenario: 1. Scale out adds new nodes to each rack 2. Table is created - all tablets are allocated to new nodes because they have low load 3. Rebalancing moves tablets from old nodes to new nodes - table balance for the new table is not fixed We're wrong to try to equalize global load when allocating tablets, and we should equalize per-table load instead, and let background load balancing fix it in a fair way. It will add to the allocated storage imbalance, but: 1. The table is initially empty, so doesn't impact actual storage imbalance. 2. It's more important to avoid overloading CPU on the nodes - imbalance hurts this aspect immediately. 3. If the table was created before imbalance was formed, we would end up in the same situation as in the problematic scenario after the patch. 4. It's the job of the load balancing to keep up with storage growing, and if it's not, scale out should kick in. Before we have CPU-aware tablet allocation, and thus can prove we have CPU capacity on the small nodes, we should respect per-table balance as this is the way in which we achieve full CPU utilization. Fixes #23631 Backport to 2025.1 because load imbalance is a serious problem in production. Closes scylladb/scylladb#23708 * github.com:scylladb/scylladb: tablets: Equalize per-table balance when allocating tablets for a new table load_sketch: Tolerate missing tablet_map when selecting for a given table tests: tablets: Simplify tests by moving common code to topology_builder
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.