# repos_asf_cassandra-dtest **Repository Path**: mirrors_community_gitbox_apache/repos_asf_cassandra-dtest ## Basic Information - **Project Name**: repos_asf_cassandra-dtest - **Description**: No description available - **Primary Language**: Unknown - **License**: Apache-2.0 - **Default Branch**: trunk - **Homepage**: None - **GVP Project**: No ## Statistics - **Stars**: 0 - **Forks**: 0 - **Created**: 2021-07-29 - **Last Updated**: 2025-09-14 ## Categories & Tags **Categories**: Uncategorized **Tags**: None ## README Cassandra Distributed Tests (DTests) ==================================== Cassandra Distributed Tests (or better known as "DTests") are a set of Python-based tests for [Apache Cassandra](http://apache.cassandra.org) clusters. DTests aim to test functionality that requires multiple Cassandra instances. Functionality that of code that can be tested in isolation should ideally be a unit test (which can be found in the actual Cassandra repository). Setup and Prerequisites ------------ Some environmental setup is required before you can start running DTests. ### Native Dependencies DTests requires the following native dependencies: * Python 3 * PIP for Python 3 * libev * git * JDK 8 (Java) #### Linux 1. ``apt-get install git-core python3 python3-pip python3-dev libev4 libev-dev`` 2. (Optional - solves warning: "jemalloc shared library could not be preloaded to speed up memory allocations"): ``apt-get install -y --no-install-recommends libjemalloc1`` #### Mac On Mac, the easiest path is to install the latest [Xcode and Command Line Utilities](https://developer.apple.com) to bootstrap your development environment and then use [Homebrew](https://brew.sh) 1. (Optional) Make sure brew is in a good state on your system ``brew doctor`` 2. ``brew install python3 libev`` 3. Make sure that AirPlay receiver is turned off because it also listens to port 7000 ### Python Dependencies There are multiple external Python dependencies required to run DTests. The current Python dependency list is maintained in a file named [requirements.txt](https://github.com/apache/cassandra-dtest/blob/trunk/requirements.txt) in the root of the `cassandra-dtest` repository. The easiest way to install these dependencies is with pip and virtualenv. **Note**: While virtualenv isn't strictly required, using virtualenv is almost always the quickest path to success as it provides common base setup across various configurations. 1. Install virtualenv: ``pip install virtualenv`` 2. Create a new virtualenv: ``virtualenv --python=python3 --no-site-packages ~/dtest`` 3. Switch/Activate the new virtualenv: ``source ~/dtest/bin/activate`` 4. Install remaining DTest Python dependencies: ``pip install -r /path/to/cassandra-dtest/requirements.txt`` Usage ----- The tests are executed by the pytest framework which includes a helpful [Usage and Invocations](https://docs.pytest.org/en/latest/usage.html) document which is a great place to start for basic invocation options when using pytest. At minimum, The only thing the framework needs to know is the location of the (compiled (hint: ``ant clean jar``)) sources for Cassandra. There are two options: Use existing sources: pytest --cassandra-dir=~/path/to/cassandra Use ccm ability to download/compile released sources from archives.apache.org: pytest --cassandra-version=1.0.0 To run a specific test file, class or individual test, you only have to pass its path as an argument: pytest --cassandra-dir=~/path/to/cassandra pending_range_test.py pytest --cassandra-dir=~/path/to/cassandra pending_range_test.py::TestPendingRangeMovements pytest --cassandra-dir=~/path/to/cassandra pending_range_test.py::TestPendingRangeMovements::test_pending_range When adding a new test or modifying an existing one, it's always a good idea to run it several times to make sure it is stable. This can be easily done with the ``--count`` option. For example, to run a test class 10 times: pytest --count=10 --cassandra-dir=~/path/to/cassandra pending_range_test.py Existing tests are probably the best place to start to look at how to write tests. Each test spawns a new fresh cluster and tears it down after the test. If a test fails, the logs for the node are saved in a `logs/` directory for analysis (it's not perfect but has been good enough so far, I'm open to better suggestions). In case you want to run tests using your own CCM branch, please, refer to the comments in requirements.txt for details how to do that. Writing Tests ------------- If you'd like to know what to expect during a code review, please see the included [CONTRIBUTING file](CONTRIBUTING.md). Debugging Tests ------------- Some general tips for debugging dtest/pytest tests #### pytest.set_trace() If there is an unexpected value being asserted on and you'd like to inspect the state of all the tests variables just before a paricular assert, add ``pytest.set_trace()`` right before the problematic code. The next time you execute the test, when that line of code is reached pytest will drop you into an interactive python debugger (pdb). From there you can use standard python options to inspect various methods and variables for debugging. #### Hung tests/hung pytest framework Debugging hung tests can be very difficult but thanks to improvements in Python 3 it's now pretty painless to get a python thread dump of all the threads currently running in the pytest process. ```python import faulthandler faulthandler.enable() ``` Adding the above code will install a signal handler into your process. When the process recieves a *SIGABRT* signal, python will dump python thread dumps for all running threads in the process. DTests installs this by default with the install_debugging_signal_handler fixture. The following is an example of what you might see if you send a *SIGABRT* signal to the pytest process while in a hung state during the test teardown phase after the successful completion of the actual dtest. ```bash (env) cassandra-dtest vcooluser$ kill -SIGABRT 24142 Fatal Python error: Aborted Thread 0x000070000f739000 (most recent call first): File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 295 in wait File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 551 in wait File "/Users/mkjellman/src/cassandra-dtest/tools/data.py", line 31 in query_c1c2 File "/Users/mkjellman/src/cassandra-dtest/bootstrap_test.py", line 91 in File "/Users/mkjellman/src/cassandra-dtest/dtest.py", line 245 in run File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 916 in _bootstrap_inner File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 884 in _bootstrap Thread 0x000070000e32d000 (most recent call first): File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncore.py", line 183 in poll2 File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncore.py", line 207 in loop File "/Users/mkjellman/env3/src/cassandra-driver/cassandra/io/asyncorereactor.py", line 119 in loop File "/Users/mkjellman/env3/src/cassandra-driver/cassandra/io/asyncorereactor.py", line 258 in _run_loop File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 864 in run File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 916 in _bootstrap_inner File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 884 in _bootstrap Current thread 0x00007fffa00dd340 (most recent call first): File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 1072 in _wait_for_tstate_lock File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/threading.py", line 1056 in join File "/Users/mkjellman/src/cassandra-dtest/dtest.py", line 253 in stop File "/Users/mkjellman/src/cassandra-dtest/dtest.py", line 580 in tearDown File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/case.py", line 608 in run File "/usr/local/Cellar/python3/3.6.3/Frameworks/Python.framework/Versions/3.6/lib/python3.6/unittest/case.py", line 653 in __call__ File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/unittest.py", line 174 in runtest File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/runner.py", line 107 in pytest_runtest_call File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/callers.py", line 180 in _multicall File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 216 in File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 222 in _hookexec File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 617 in __call__ File "/Users/mkjellman/env3/lib/python3.6/site-packages/flaky/flaky_pytest_plugin.py", line 273 in File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/runner.py", line 191 in __init__ File "/Users/mkjellman/env3/lib/python3.6/site-packages/flaky/flaky_pytest_plugin.py", line 274 in call_runtest_hook File "/Users/mkjellman/env3/lib/python3.6/site-packages/flaky/flaky_pytest_plugin.py", line 118 in call_and_report File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/runner.py", line 77 in runtestprotocol File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/runner.py", line 63 in pytest_runtest_protocol File "/Users/mkjellman/env3/lib/python3.6/site-packages/flaky/flaky_pytest_plugin.py", line 81 in pytest_runtest_protocol File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/callers.py", line 180 in _multicall File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 216 in File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 222 in _hookexec File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 617 in __call__ File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/main.py", line 164 in pytest_runtestloop File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/callers.py", line 180 in _multicall File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 216 in File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 222 in _hookexec File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 617 in __call__ File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/main.py", line 141 in _main File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/main.py", line 103 in wrap_session File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/main.py", line 134 in pytest_cmdline_main File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/callers.py", line 180 in _multicall File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 216 in File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 222 in _hookexec File "/Users/mkjellman/env3/lib/python3.6/site-packages/pluggy/__init__.py", line 617 in __call__ File "/Users/mkjellman/env3/lib/python3.6/site-packages/_pytest/config.py", line 59 in main File "/Users/mkjellman/env3/bin/pytest", line 11 in Abort trap: 6 ``` #### Debugging Issues with Fixtures and Test Setup/Teardown pytest can appear to be doing "magic" more often than not. One place it may be hard to follow what actual code will get executed by normal code inspection alone is determining which fixtures will run for a given test and in what order. pytest provides a ``--setup-plan`` command line argument. When pytest is invoked with this argument it will print a execution plan including all fixtures and tests that actually running the test will invoke. The below is an example for the current execution plan pytest generates for dtest *auth_test.py::TestAuthRoles::test_create_drop_role* ```bash (env3) Michaels-MacBook-Pro:cassandra-dtest mkjellman$ pytest --cassandra-dir=/Users/mkjellman/src/mkjellman-oss-github-cassandra-trunk auth_test.py::TestAuthRoles::test_create_drop_role --setup-plan ====================================================================== test session starts ====================================================================== platform darwin -- Python 3.6.3, pytest-3.3.0, py-1.5.2, pluggy-0.6.0 rootdir: /Users/mkjellman/src/cassandra-dtest, inifile: pytest.ini plugins: timeout-1.2.1, raisesregexp-2.1, nose2pytest-1.0.8, flaky-3.4.0 collected 1 item auth_test.py SETUP S install_debugging_signal_handler SETUP C fixture_logging_setup SETUP F fixture_dtest_setup_overrides SETUP F fixture_log_test_name_and_date SETUP F fixture_maybe_skip_tests_requiring_novnodes SETUP F parse_dtest_config SETUP F fixture_dtest_setup (fixtures used: fixture_dtest_setup_overrides, fixture_logging_setup, parse_dtest_config) SETUP F fixture_since (fixtures used: fixture_dtest_setup) SETUP F fixture_dtest_config (fixtures used: fixture_logging_setup) SETUP F set_dtest_setup_on_function (fixtures used: fixture_dtest_config, fixture_dtest_setup) auth_test.py::TestAuthRoles::()::test_create_drop_role (fixtures used: fixture_dtest_config, fixture_dtest_setup, fixture_dtest_setup_overrides, fixture_log_test_name_and_date, fixture_logging_setup, fixture_maybe_skip_tests_requiring_novnodes, fixture_since, install_debugging_signal_handler, parse_dtest_config, set_dtest_setup_on_function) TEARDOWN F set_dtest_setup_on_function TEARDOWN F fixture_dtest_config TEARDOWN F fixture_since TEARDOWN F fixture_dtest_setup TEARDOWN F parse_dtest_config TEARDOWN F fixture_maybe_skip_tests_requiring_novnodes TEARDOWN F fixture_log_test_name_and_date TEARDOWN F fixture_dtest_setup_overrides TEARDOWN C fixture_logging_setup TEARDOWN S install_debugging_signal_handler ===Flaky Test Report=== ===End Flaky Test Report=== ====================================================================== 0 tests deselected ======================================================================= ================================================================= no tests ran in 0.12 seconds ================================================================== ``` #### Instances Failing to Start (Unclean Test Teardown) Getting into a state (especially while writing new tests or debugging problamatic ones) where pytest/dtest fails to fully tear-down all local C* instancse that were started. You can use this handy one liner to kill all C* instances in one go: ```bash ps aux | grep -ie CassandraDaemon | grep java | awk '{print $2}' | xargs kill ``` Links ------- * [ccm](https://github.com/apache/cassandra-ccm) * [pytest](https://docs.pytest.org/) * [Python Driver](http://datastax.github.io/python-driver/installation.html) * [CQL over Thrift Driver](http://code.google.com/a/apache-extras.org/p/cassandra-dbapi2/)