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lbrycrd/test/README.md
MarcoFalke 5029e94f85
Merge #14519: tests: add utility to easily profile node performance with perf 
13782b8ba8 docs: add perf section to developer docs (James O'Beirne)
58180b5fd4 tests: add utility to easily profile node performance with perf (James O'Beirne)

Pull request description:

  Adds a context manager to easily (and selectively) profile node performance during functional test execution using `perf`.

  While writing some tests, I encountered some odd bitcoind slowness. I wrote up a utility (`TestNode.profile_with_perf`) that generates performance diagnostics for a node by running `perf` during the execution of a particular region of test code.

  `perf` usage is detailed in the excellent (and sadly unmerged) https://github.com/bitcoin/bitcoin/pull/12649; all due props to @eklitzke.

  ### Example

  ```python
  with node.profile_with_perf("large-msgs"):
      for i in range(200):
          node.p2p.send_message(some_large_msg)
      node.p2p.sync_with_ping()
  ```

  This generates a perf data file in the test node's datadir (`/tmp/testtxmpod0y/node0/node-0-TestName-large-msgs.perf.data`).

  Running `perf report` generates nice output about where the node spent most of its time while running that part of the test:

  ```bash
  $ perf report -i /tmp/testtxmpod0y/node0/node-0-TestName-large-msgs.perf.data --stdio \
    | c++filt \
    | less

  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 135  of event 'cycles:pp'
  # Event count (approx.): 1458205679493582
  #
  # Children      Self  Command          Shared Object        Symbol
  # ........  ........  ...............  ...................  ........................................................................................................................................................................................................................................................................
  #
      70.14%     0.00%  bitcoin-net      bitcoind             [.] CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)
                  |
                  ---CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)

      70.14%     0.00%  bitcoin-net      bitcoind             [.] CNetMessage::readData(char const*, unsigned int)
                  |
                  ---CNetMessage::readData(char const*, unsigned int)
                     CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)

      35.52%     0.00%  bitcoin-net      bitcoind             [.] std::vector<char, zero_after_free_allocator<char> >::_M_fill_insert(__gnu_cxx::__normal_iterator<char*, std::vector<char, zero_after_free_allocator<char> > >, unsigned long, char const&)
                  |
                  ---std::vector<char, zero_after_free_allocator<char> >::_M_fill_insert(__gnu_cxx::__normal_iterator<char*, std::vector<char, zero_after_free_allocator<char> > >, unsigned long, char const&)
                     CNetMessage::readData(char const*, unsigned int)
                     CNode::ReceiveMsgBytes(char const*, unsigned int, bool&)

  ...
  ```

Tree-SHA512: 9ac4ceaa88818d5eca00994e8e3c8ad42ae019550d6583972a0a4f7b0c4f61032e3d0c476b4ae58756bc5eb8f8015a19a7fc26c095bd588f31d49a37ed0c6b3e
2019-02-05 17:40:16 -05:00

7 KiB
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This directory contains integration tests that test bitcoind and its utilities in their entirety. It does not contain unit tests, which can be found in /src/test, /src/wallet/test, etc.

This directory contains the following sets of tests:

  • functional which test the functionality of bitcoind and bitcoin-qt by interacting with them through the RPC and P2P interfaces.
  • util which tests the bitcoin utilities, currently only bitcoin-tx.
  • lint which perform various static analysis checks.

The util tests are run as part of make check target. The functional tests and lint scripts are run by the travis continuous build process whenever a pull request is opened. All sets of tests can also be run locally.

Running tests locally

Before tests can be run locally, Bitcoin Core must be built. See the building instructions for help.

Functional tests

Dependencies

The ZMQ functional test requires a python ZMQ library. To install it:

  • on Unix, run sudo apt-get install python3-zmq
  • on mac OS, run pip3 install pyzmq

Running the tests

Individual tests can be run by directly calling the test script, e.g.:

test/functional/feature_rbf.py

or can be run through the test_runner harness, eg:

test/functional/test_runner.py feature_rbf.py

You can run any combination (incl. duplicates) of tests by calling:

test/functional/test_runner.py <testname1> <testname2> <testname3> ...

Run the regression test suite with:

test/functional/test_runner.py

Run all possible tests with

test/functional/test_runner.py --extended

By default, up to 4 tests will be run in parallel by test_runner. To specify how many jobs to run, append --jobs=n

The individual tests and the test_runner harness have many command-line options. Run test_runner.py -h to see them all.

Troubleshooting and debugging test failures

Resource contention

The P2P and RPC ports used by the bitcoind nodes-under-test are chosen to make conflicts with other processes unlikely. However, if there is another bitcoind process running on the system (perhaps from a previous test which hasn't successfully killed all its bitcoind nodes), then there may be a port conflict which will cause the test to fail. It is recommended that you run the tests on a system where no other bitcoind processes are running.

On linux, the test_framework will warn if there is another bitcoind process running when the tests are started.

If there are zombie bitcoind processes after test failure, you can kill them by running the following commands. Note that these commands will kill all bitcoind processes running on the system, so should not be used if any non-test bitcoind processes are being run.

killall bitcoind

or

pkill -9 bitcoind
Data directory cache

A pre-mined blockchain with 200 blocks is generated the first time a functional test is run and is stored in test/cache. This speeds up test startup times since new blockchains don't need to be generated for each test. However, the cache may get into a bad state, in which case tests will fail. If this happens, remove the cache directory (and make sure bitcoind processes are stopped as above):

rm -rf cache
killall bitcoind
Test logging

The tests contain logging at different levels (debug, info, warning, etc). By default:

  • when run through the test_runner harness, all logs are written to test_framework.log and no logs are output to the console.
  • when run directly, all logs are written to test_framework.log and INFO level and above are output to the console.
  • when run on Travis, no logs are output to the console. However, if a test fails, the test_framework.log and bitcoind debug.logs will all be dumped to the console to help troubleshooting.

To change the level of logs output to the console, use the -l command line argument.

test_framework.log and bitcoind debug.logs can be combined into a single aggregate log by running the combine_logs.py script. The output can be plain text, colorized text or html. For example:

combine_logs.py -c <test data directory> | less -r

will pipe the colorized logs from the test into less.

Use --tracerpc to trace out all the RPC calls and responses to the console. For some tests (eg any that use submitblock to submit a full block over RPC), this can result in a lot of screen output.

By default, the test data directory will be deleted after a successful run. Use --nocleanup to leave the test data directory intact. The test data directory is never deleted after a failed test.

Attaching a debugger

A python debugger can be attached to tests at any point. Just add the line:

import pdb; pdb.set_trace()

anywhere in the test. You will then be able to inspect variables, as well as call methods that interact with the bitcoind nodes-under-test.

If further introspection of the bitcoind instances themselves becomes necessary, this can be accomplished by first setting a pdb breakpoint at an appropriate location, running the test to that point, then using gdb to attach to the process and debug.

For instance, to attach to self.node[1] during a run:

2017-06-27 14:13:56.686000 TestFramework (INFO): Initializing test directory /tmp/user/1000/testo9vsdjo3

use the directory path to get the pid from the pid file:

cat /tmp/user/1000/testo9vsdjo3/node1/regtest/bitcoind.pid
gdb /home/example/bitcoind <pid>

Note: gdb attach step may require ptrace_scope to be modified, or sudo preceding the gdb. See this link for considerations: https://www.kernel.org/doc/Documentation/security/Yama.txt

Profiling

An easy way to profile node performance during functional tests is provided for Linux platforms using perf.

Perf will sample the running node and will generate profile data in the node's datadir. The profile data can then be presented using perf report or a graphical tool like hotspot.

To generate a profile during test suite runs, use the --perf flag.

To see render the output to text, run

perf report -i /path/to/datadir/send-big-msgs.perf.data.xxxx --stdio | c++filt | less

For ways to generate more granular profiles, see the README in test/functional.

Util tests

Util tests can be run locally by running test/util/bitcoin-util-test.py. Use the -v option for verbose output.

Lint tests

Dependencies

The lint tests require codespell and flake8. To install: pip3 install codespell flake8.

Running the tests

Individual tests can be run by directly calling the test script, e.g.:

test/lint/lint-filenames.sh

You can run all the shell-based lint tests by running:

test/lint/lint-all.sh

Writing functional tests

You are encouraged to write functional tests for new or existing features. Further information about the functional test framework and individual tests is found in test/functional.