770b91447b
`dirty_memory_manager` tracks two quantities about memtable memory usage: "real" and "unspooled" memory usage. "real" is the total memory usage (sum of `occupancy().total_space()`) by all memtable LSA regions, plus a upper-bound estimate of the size of memtable data which has already moved to the cache region but isn't evictable (merged into the cache) yet. "unspooled" is the difference between total memory usage by all memtable LSA regions, and the total flushed memory (sum of `_flushed_memory`) of memtables. `dirty_memory_manager` controls the shares of compaction and/or blocks writes when these quantities cross various thresholds. "Total flushed memory" isn't a well defined notion, since the actual consumption of memory by the same data can vary over time due to LSA compactions, and even the data present in memtable can change over the course of the flush due to removals of outdated MVCC versions. So `_flushed_memory` is merely an approximation computed by `flush_reader` based on the data passing through it. This approximation is supposed to be a conservative lower bound. In particular, `_flushed_memory` should be not greater than `occupancy().total_space()`. Otherwise, for example, "unspooled" memory could become negative (and/or wrap around) and weird things could happen. There is an assertion in `~flush_memory_accounter` which checks that `_flushed_memory < occupancy().total_space()` at the end of flush. But it can fail. Without additional treatment, the memtable reader sometimes emits data which is already deleted. (In particular, it emites rows covered by a partition tombstone in a newer MVCC version.) This data is seen by `flush_reader` and accounted in `_flushed_memory`. But this data can be garbage-collected by the `mutation_cleaner` later during the flush and decrease `total_memory` below `_flushed_memory`. There is a piece of code in `mutation_cleaner` intended to prevent that. If `total_memory` decreases during a `mutation_cleaner` run, `_flushed_memory` is lowered by the same amount, just to preserve the asserted property. (This could also make `_flushed_memory` quite inaccurate, but that's considered acceptable). But that only works if `total_memory` is decreased during that run. It doesn't work if the `total_memory` decrease (enabled by the new allocator holes made by `mutation_cleaner`'s garbage collection work) happens asynchronously (due to memory reclaim for whatever reason) after the run. This patch fixes that by tracking the decreases of `total_memory` closer to the source. Instead of relying on `mutation_cleaner` to notify the memtable if it lowers `total_memory`, the memtable itself listens for notifications about LSA segment deallocations. It keeps `_flushed_memory` equal to the reader's estimate of flushed memory decreased by the change in `total_memory` since the beginning of flush (if it was positive), and it keeps the amount of "spooled" memory reported to the `dirty_memory_manager` at `max(0, _flushed_memory)`. Fixes scylladb/scylladb#21413 Backport candidate because it fixes a crash that can happen in existing stable branches. Closes scylladb/scylladb#21638 * github.com:scylladb/scylladb: memtable: ensure _flushed_memory doesn't grow above total memory usage replica/memtable: move region_listener handlers from dirty_memory_manager to memtable
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.