d8cc029a5e
The initial problem:
Some of the tests in test_protocol_exceptions.py started failing. The failure is
on the condition that no more than `cpp_exception_threshold` happened.
Test logic:
These tests assert that specific code paths do not throw an exception anymore.
Initial implementation ran a code path once, and asserted there were 0 exceptions.
Sometimes an exception or several can occur, not directly related to the code paths
the tests check, but those would fail the tests.
The solution was to run the tests multiple times. If there is a regression, there
would be at least as many exceptions thrown as there are test runs. If there is no
regression, a few exceptions might happen, up to 10 per 100 test runs.
I have arbitrarily chosen `run_count = 100` and `cpp_exception_threshold = 10` values.
Note that the exceptions are counted per shard, not per code path.
The new problem:
The occassional exceptions thrown by some parts of the server now throw a bit more
than before. Based on the logs linked on the issues, it is usually 12.
There are possibly multiple ways to resolve the issue. I have considered logging
exceptions and parsing them. I would have to filter exception logs only for wanted
exceptions. However, if a new, different exception is introduced, it might not be
counted.
Another approach is to just increase the threshold a bit. The issue of throwing
more exceptions than before in some other server modules should be addressed by
a set of tests for that module, just like these tests check protocol exceptions,
not caring who used protocol check code paths.
For those reasons, the solution implemented here is to increase `cpp_exception_threshold`
to `20`. It will not make the tests unreliable, because, as mentioned, if there is a
regression, there would be at least `run_count` exceptions per `run_count` test runs
(1 exception per single test run).
Still, to make "background exceptions" occurence a bit more normalized, `run_count` too
is doubled, from `100` to `200`. At the first glance this looks like nothing is changed,
but actually doubling both run count and exception threshold here implies that the
exception burst does not scale as much as run count, it is just that the "jitter" is
bigger than the old threshold.
Fixes #27247
Fixes #27325
(cherry picked from commit 807fc68dc5)
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.