Added support to track and limit the memory usage by sstable components. A reclaimable component of an SSTable is one from which memory can be reclaimed. SSTables and their managers now track such reclaimable memory and limit the component memory usage accordingly. A new configuration variable defines the memory reclaim threshold. If the total memory of the reclaimable components exceeds this limit, memory will be reclaimed to keep the usage under the limit. This PR considers only the bloom filters as reclaimable and adds support to track and limit them as required.
The feature can be manually verified by doing the following :
1. run a single-node single-shard 1GB cluster
2. create a table with bloom-filter-false-positive-chance of 0.001 (to intentionally cause large bloom filter)
3. populate with tiny partitions
4. watch the bloom filter metrics get capped at 100MB
The default value of the `components_memory_reclaim_threshold` config variable which controls the reclamation process is `.1`. This can also be reduced further during manual tests to easily hit the threshold and verify the feature.
Fixes#17747Closesscylladb/scylladb#17771
* github.com:scylladb/scylladb:
test_bloom_filter.py: disable reclaiming memory from components
sstable_datafile_test: add tests to verify auto reclamation of components
test/lib: allow overriding available memory via test_env_config
sstables_manager: support reclaiming memory from components
sstables_manager: store available memory size
sstables_manager: add variable to track component memory usage
db/config: add a new variable to limit memory used by table components
sstable_datafile_test: add testcase to verify reclamation from sstables
sstables: support reclaiming memory from components
ffdd47c2b1