bfdd4f7776
Split prepare can run concurrently with repair.
Consider this:
1) split prepare starts
2) incremental repair starts
3) split prepare finishes
4) incremental repair produces unsplit sstable
5) split is not happening on sstable produced by repair
5.1) that sstable is not marked as repaired yet
5.2) might belong to repairing set (has compaction disabled)
6) split executes
7) repairing or repaired set has unsplit sstable
If split was acked to coordinator (meaning prepare phase finished),
repair must make sure that all sstables produced by it are split.
It's not happening today with incremental repair because it disables
split on sstables belonging to repairing group. And there's a window
where sstables produced by repair belong to that group.
To solve the problem, we want the invariant where all sealed sstables
will be split.
To achieve this, streaming consumers are patched to produce unsealed
sstable, and the new variant add_new_sstable_and_update_cache() will
take care of splitting the sstable while it's unsealed.
If no split is needed, the new sstable will be sealed and attached.
This solution was also needed to interact nicely with out of space
prevention too. If disk usage is critical, split must not happen on
restart, and the invariant aforementioned allows for it, since any
unsplit sstable left unsealed will be discarded on restart.
The streaming consumer will fail if disk usage is critical too.
The reason interposer consumer doesn't fully solve the problem is
because incremental repair can start before split, and the sstable
being produced when split decision was emitted must be split before
attached. So we need a solution which covers both scenarios.
Fixes #26041.
Fixes #27414.
Should be backported to 2025.4 that contains incremental repair
Closes scylladb/scylladb#26528
* github.com:scylladb/scylladb:
test: Add reproducer for split vs intra-node migration race
test: Verify split failure on behalf of repair during critical disk utilization
test: boost: Add failure_when_adding_new_sstable_test
test: Add reproducer for split vs incremental repair race condition
compaction: Fail split of new sstable if manager is disabled
replica: Don't split in do_add_sstable_and_update_cache()
streaming: Leave sstables unsealed until attached to the table
replica: Wire add_new_sstables_and_update_cache() into intra-node streaming
replica: Wire add_new_sstable_and_update_cache() into file streaming consumer
replica: Wire add_new_sstable_and_update_cache() into streaming consumer
replica: Document old add_sstable_and_update_cache() variants
replica: Introduce add_new_sstables_and_update_cache()
replica: Introduce add_new_sstable_and_update_cache()
replica: Account for sstables being added before ACKing split
replica: Remove repair read lock from maybe_split_new_sstable()
compaction: Preserve state of input sstable in maybe_split_new_sstable()
Rename maybe_split_sstable() to maybe_split_new_sstable()
sstables: Allow storage::snapshot() to leave destination sstable unsealed
sstables: Add option to leave sstable unsealed in the stream sink
test: Verify unsealed sstable can be compacted
sstables: Allow unsealed sstable to be loaded
sstables: Restore sstable_writer_config::leave_unsealed
Scylla unit tests using C++ and the Boost test framework
The source files in this directory are Scylla unit tests written in C++ using the Boost.Test framework. These unit tests come in three flavors:
-
Some simple tests that check stand-alone C++ functions or classes use Boost's
BOOST_AUTO_TEST_CASE. -
Some tests require Seastar features, and need to be declared with Seastar's extensions to Boost.Test, namely
SEASTAR_TEST_CASE. -
Even more elaborate tests require not just a functioning Seastar environment but also a complete (or partial) Scylla environment. Those tests use the
do_with_cql_env()ordo_with_cql_env_thread()function to set up a mostly-functioning environment behaving like a single-node Scylla, in which the test can run.
While we have many tests of the third flavor, writing new tests of this type should be reserved to white box tests - tests where it is necessary to inspect or control Scylla internals that do not have user-facing APIs such as CQL. In contrast, black-box tests - tests that can be written only using user-facing APIs, should be written in one of newer test frameworks that we offer - such as test/cqlpy or test/alternator (in Python, using the CQL or DynamoDB APIs respectively) or test/cql (using textual CQL commands), or - if more than one Scylla node is needed for a test - using the test/topology* framework.
Running tests
Because these are C++ tests, they need to be compiled before running.
To compile a single test executable row_cache_test, use a command like
ninja build/dev/test/boost/row_cache_test
You can also use ninja dev-test to build all C++ tests, or use
ninja deb-build to build the C++ tests and also the full Scylla executable
(however, note that full Scylla executable isn't needed to run Boost tests).
Replace "dev" by "debug" or "release" in the examples above and below to use the "debug" build mode (which, importantly, compiles the test with ASAN and UBSAN enabling on and helps catch difficult-to-catch use-after-free bugs) or the "release" build mode (optimized for run speed).
To run an entire test file row_cache_test, including all its test
functions, use a command like:
build/dev/test/boost/row_cache_test -- -c1 -m1G
to run a single test function test_reproduce_18045() from the longer test
file, use a command like:
build/dev/test/boost/row_cache_test -t test_reproduce_18045 -- -c1 -m1G
In these command lines, the parameters before the -- are passed to
Boost.Test, while the parameters after the -- are passed to the test code,
and in particular to Seastar. In this example Seastar is asked to run on one
CPU (-c1) and use 1G of memory (-m1G) instead of hogging the entire
machine. The Boost.Test option -t test_reproduce_18045 asks it to run just
this one test function instead of all the test functions in the executable.
Unfortunately, interrupting a running test with control-C while doesn't
work. This is a known bug (#5696). Kill a test with SIGKILL (-9) if you
need to kill it while it's running.
Boost tests can also be run using test.py - which is a script that provides a uniform way to run all tests in scylladb.git - C++ tests, Python tests, etc.
Execution with pytest
To run all tests with pytest execute
pytest test/boost
To execute all tests in one file, provide the path to the source filename as a parameter
pytest test/boost/aggregate_fcts_test.cc
Since it's a normal path, autocompletion works in the terminal out of the box.
To execute only one test function, provide the path to the source file and function name
pytest --mode dev test/boost/aggregate_fcts_test.cc::test_aggregate_avg
To provide a specific mode, use the next parameter --mode dev,
if parameter isn't provided pytest tries to use ninja mode_list to find out the compiled modes.
Parallel execution is controlled by pytest-xdist and the parameter -n auto.
This command starts tests with the number of workers equal to CPU cores.
The useful command to discover the tests in the file or directory is
pytest --collect-only -q --mode dev test/boost/aggregate_fcts_test.cc
That will return all test functions in the file.
To execute only one function from the test, you can invoke the output from the previous command.
However, suffix for mode should be skipped.
For example,
output shows in the terminal something like this test/boost/aggregate_fcts_test.cc::test_aggregate_avg.dev.
So to execute this specific test function, please use the next command
pytest --mode dev test/boost/aggregate_fcts_test.cc::test_aggregate_avg
Writing tests
Because of the large build time and build size of each separate test executable, it is recommended to put test functions into relatively large source files. But not too large - to keep compilation time of a single source file (during development) at reasonable levels.
When adding new source files in test/boost, don't forget to list the new source file in configure.py and also in CMakeLists.txt. The former is needed by our CI, but the latter is preferred by some developers.