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Coverage in parallel failing #883

rowleya opened this issue Dec 16, 2019 · 23 comments

Coverage in parallel failing #883

rowleya opened this issue Dec 16, 2019 · 23 comments
bug Something isn't working fixed


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rowleya commented Dec 16, 2019

Describe the bug
When we run pytest using multiple processes with coverage on our tests, we get an error message that seems to be related to the integration of SQLite. The error we get is available from our integration test suite here:

Replicated a sample of the output here in case this disappears!

[gw7] linux -- Python 3.6.7 /usr/bin/python3
self = <SqliteDb @0x7f9efba0c1d0 debug=None filename='/var/lib/jenkins/workspace/ation_Tests_neuron_recorder_agdr/.coverage' nest=0 con=None>
sql = 'insert into meta (key, value) values (?, ?)'
parameters = ('has_arcs', '1')

    def execute(self, sql, parameters=()):
        """Same as :meth:`python:sqlite3.Connection.execute`."""
        if self.debug:
            tail = " with {!r}".format(parameters) if parameters else ""
            self.debug.write("Executing {!r}{}".format(sql, tail))
>           return self.con.execute(sql, parameters)
E           sqlite3.IntegrityError: UNIQUE constraint failed: meta.key

To Reproduce
How can we reproduce the problem? Please be specific.

  1. What version of Python are you using?
  2. What version of are you using? The output of coverage debug sys is helpful.
  3. What versions of what packages do you have installed? The output of pip freeze is helpful.
    See above link for details.
  4. What code are you running? Give us a specific commit of a specific repo that we can check out.
    Integration tests in Jenkins; see above for details.
  5. What commands did you run?
py.test SpiNNUtils/unittests -rs -n auto --forked --show-progress --cov-branch --cov spynnaker8 --cov spynnaker --cov spinn_front_end_common --cov pacman --cov data_specification --cov spinnman --cov spinn_machine --cov spinn_storage_handlers --cov spalloc --cov spinn_utilities --junitxml junit/SpiNNUtils.xml --cov-report xml:coverage.xml --cov-append --timeout 1200

Expected behavior
A clear and concise description of what you expected to happen.
No error message; protection against writing from mulitple processes through checking for key in database before attempted insert.

Additional context
Add any other context about the problem here.

@rowleya rowleya added the bug Something isn't working label Dec 16, 2019
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Facing the same issue. Is there any workaround, pls?

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nedbat commented Dec 16, 2019

The simplest way to avoid this issue for now is to pin to 4.5.4. Another thing that would help me find a solution for you is to provide me with specific, complete instructions that would let me reproduce the problem.

@nedbat nedbat added this to the 5.0.1 milestone Dec 16, 2019
@nedbat nedbat added the question Further information is requested label Dec 17, 2019
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nedbat commented Dec 17, 2019

@rowleya Can you give me specific instructions I can follow to reproduce the problem? What repo, what commit, what commands to run?

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I couldn't reproduce reliably the issue we have on this CI Pipeline

But here are few things that might help:

  • The bug happen when using pytest with both --cov-append --cov=X options. Without --cov-append, it works fine.
  • When the error sqlite3.IntegrityError: UNIQUE constraint failed: meta.key is raised (while inserting a new entry with has_arcs key in meta table), there is already an entry in the meta table with ('has_arcs', '0')

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rowleya commented Dec 17, 2019

The specific instructions that seem to fail for me are:

python3.6 -m virtualenv test
cd test
source bin/activate
git clone
cd SpiNNUtils && python develop && cd ..
pip install python-coveralls "coverage>=4.4"
pip install pytest-instafail pytest-xdist pytest-cov pytest-progress pytest-timeout pytest-forked
py.test SpiNNUtils/unittests -rs -n auto --forked --show-progress --cov-branch --cov spynnaker8 --cov spynnaker --cov spinn_front_end_common --cov pacman --cov data_specification --cov spinnman --cov spinn_machine --cov spinn_storage_handlers --cov spalloc --cov spinn_utilities --junitxml junit/SpiNNUtils.xml --cov-report xml:coverage.xml --cov-append --timeout 1200

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rowleya commented Dec 17, 2019

It makes sense that --cov-append is the issue; I am trying to achieve something specific with this, which is to run lots of tests from different repositories, including integration tests, and get the overall coverage, so this is essential.

A quick test shows that without the -n auto --forked but with the other arguments (including --cov-append) this also works. It fails some of the tests due to the above not installing all the requirements, but the coverage module doesn't fail; the extra dependencies are:

pip install numpy testfixtures httpretty

Christian-B added a commit to SpiNNakerManchester/sPyNNaker8 that referenced this issue Dec 17, 2019
Christian-B added a commit to SpiNNakerManchester/SpiNNakerGraphFrontEnd that referenced this issue Dec 17, 2019
Urth added a commit to Urth/coveragepy_883 that referenced this issue Dec 18, 2019
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Urth commented Dec 18, 2019

I found a reproducible configuration which was plaguing one of our projects. The coverage database/internals will enter a broken state when sub-process coverage is used.
A minimal example can be found at

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sco1 commented Dec 19, 2019

I believe I might be seeing a similar issue in one of my latest builds, though in our case it seems specific to having a test that invokes subprocess.

Here is the specific commit that triggers the CI failure (3.6 log, azure build link, tox config). While this fails in CI for 3.6, 3.7, and 3.8, on my MBP it only fails for 3.6. Removing the test (the one with subprocess) eliminates the failure.

I will work on capturing more details, but might not be able to get them up until tomorrow.

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nedbat commented Jan 1, 2020

This works to reproduce the problem:

git clone
cd flake8-annotations
git checkout 1dfaab8100a686e2171b0e27d0c21cc195be4db6
mktmpenv -p python3.6 -n
pip install tox
rm .coverage; tox -e py36 -- testing/

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nedbat commented Jan 1, 2020


While this fails in CI for 3.6, 3.7, and 3.8, on my MBP it only fails for 3.6.

The test fails if there is no .coverage file, which is why CI fails always, but only the first tox env fails on your laptop. With "rm .coverage", it fails on all versions of Python locally.

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nedbat commented Jan 1, 2020

One solution is to add this to a .coveragerc file:

parallel = True

Removing --cov-append also prevents the error. I'm not sure which of these gives you the proper measurements, if either.
I don't know if there's a better solution that can be built in to or to pytest-cov.

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sco1 commented Jan 2, 2020

Thanks Ned, away from a dev machine until this evening to check this out, but I don't think I'm following why the missing coverage file is ultimate source of the problem.

I can't speak for the OP, but for my project if the malfunctioning test is removed then the test suite runs fine, both locally and in CI. For example, the latest release commit (CI) runs without issue.

edit: I've added the suggested .coveragerc file and it seems to resolve the issue, yay!

sco1 added a commit to sco1/flake8-annotations that referenced this issue Jan 2, 2020
Per upstream issue, this workaround keeps coverage from failing when trying to append to a nonexistent .coverage file.

See: nedbat/coveragepy#883
@nedbat nedbat removed this from the 5.0.2 milestone Jan 6, 2020
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Is there any drawback to using:

parallel = True


And if there isn't, why is it not the default ? (honest question)

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nedbat commented Mar 9, 2020

The drawback to parallel = True is that you need an explicit coverage combine step before you can use coverage report or coverage html (or any other reporting).

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MartinThoma commented Mar 17, 2020

Just to highlight: Adding the following section to the setup.cfg fixes the issue:


edit: Strange ... I think this worked a while ago. Now it doesn't anymore.

MartinThoma added a commit to MartinThoma/edapy that referenced this issue Mar 17, 2020
MartinThoma added a commit to MartinThoma/edapy that referenced this issue Mar 17, 2020
skirpichev added a commit to skirpichev/diofant that referenced this issue Mar 17, 2020
@nedbat nedbat removed this from the 5.0.4 milestone Mar 17, 2020
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KingDarBoja commented Mar 17, 2020

Having the same issue since the update to 5.0.4. On 5.0.3 is working fine on GitHub Actions 😢

Does the parallel option is required if I am trying to do something like below?

pytest --cov-report= -vv &
pytest --cov-report= --cov-append -vv &
pytest --cov-report= --cov-append -vv &
coverage report -m

sf-project-io pushed a commit to softwarefactory-project/rdopkg that referenced this issue Mar 18, 2020
Since Fedora 31, some macros that we used in RDO packages need to
be fixed. Fixing this also exposed an issue when running coverage
tests in parallel [1], so we need to update the way we are running
tests to cope up.

[1] - nedbat/coveragepy#883

Change-Id: I5c106b31106d98efc0c115510aaf962e79cc0c69
skirpichev added a commit to skirpichev/diofant that referenced this issue Mar 30, 2020
Used parallel=True option to workaround nedbat/coveragepy#883
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JulienPalard commented Jun 27, 2020


The issue happen when running multiple coverage combine in parallel from multiple distincts coverage runs, as there is no way for coverage to tell which .coverage.* files are from which set of coverage run. It happen typically when using pytest-cov in parallel, as pytest-cov always uses a combine step, even when a single .coverage file is needed.

The way to tell coverage which set of .coverage.* file are from which set of runs (with or without tox), is to specify the .coverage filename. For tox, one can use:

setenv =

I think this issue can be closed, but pytest-cov may have to document this better.

Long version

I'm trying to reproduce it today, I'm able to reproduce it with either tox -p all and:

$ /tmp/3.6/bin/pytest --cov-report term-missing --cov-fail-under=100 --cov src/mediaserver/ &
/tmp/3.7/bin/pytest --cov-report term-missing --cov-fail-under=100 --cov src/mediaserver/ &
/tmp/3.8/bin/pytest --cov-report term-missing --cov-fail-under=100 --cov src/mediaserver/

It looks like it's always an issue near .coverage, as I got those errors:

coverage.misc.CoverageException: Couldn't use data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.40820.348297': no such table: file


INTERNALERROR> coverage.misc.CoverageException: Data file '/home/mdk/clones/coverage-reproducer/.coverage' doesn't seem to be a coverage data file: Couldn't use data file '/home/mdk/clones/coverage-reproducer/.coverage': no such table: coverage_schema

Interestingly I got a no such table: file in .coverage.seraph.41964.820593 while not using --parallel-mode. Happen that pytest-cov is adding it.


INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/coverage/", line 1048, in execute
INTERNALERROR>     return self.con.execute(sql, parameters)
INTERNALERROR> sqlite3.OperationalError: no such table: file
INTERNALERROR> During handling of the above exception, another exception occurred:
INTERNALERROR> Traceback (most recent call last):
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/_pytest/", line 191, in wrap_session
INTERNALERROR>     session.exitstatus = doit(config, session) or 0
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/_pytest/", line 247, in _main
INTERNALERROR>     config.hook.pytest_runtestloop(session=session)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pluggy/", line 286, in __call__
INTERNALERROR>     return self._hookexec(self, self.get_hookimpls(), kwargs)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pluggy/", line 93, in _hookexec
INTERNALERROR>     return self._inner_hookexec(hook, methods, kwargs)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pluggy/", line 87, in 
INTERNALERROR>     firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pluggy/", line 203, in _multicall
INTERNALERROR>     gen.send(outcome)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pytest_cov/", line 271, in pytest_runtestloop
INTERNALERROR>     self.cov_controller.finish()
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pytest_cov/", line 46, in ensure_topdir_wrapper
INTERNALERROR>     return meth(self, *args, **kwargs)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/pytest_cov/", line 231, in finish
INTERNALERROR>     self.cov.stop()
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/coverage/", line 687, in combine
INTERNALERROR>     combine_parallel_data(self._data, aliases=aliases, data_paths=data_paths, strict=strict)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/coverage/", line 117, in combine_parallel_data
INTERNALERROR>     data.update(new_data, aliases=aliases)
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/coverage/", line 575, in update
INTERNALERROR>     cur = conn.execute('select path from file')
INTERNALERROR>   File "/tmp/3.6/lib/python3.6/site-packages/coverage/", line 1065, in execute
INTERNALERROR>     raise CoverageException("Couldn't use data file {!r}: {}".format(self.filename, msg))
INTERNALERROR> coverage.misc.CoverageException: Couldn't use data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.41964.820593': no such table: file

I see that pytest-cov is instanciating two Coverage, which may lead to the two sqlite file being overwritten.

I'm trying with 3 pytest-cov in parallel, with export COVERAGE_DEBUG=dataio, what I'm getting is surprising:

First process (everything OK)
Erasing data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46134.640334'
Creating data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46134.640334'
Combining data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46134.640334'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46134.640334'
Erasing data file '/home/mdk/clones/coverage-reproducer/.coverage'
Creating data file '/home/mdk/clones/coverage-reproducer/.coverage'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage'
Deleting combined data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46134.640334'
2nd process (get mixed up with 3st one)
Erasing data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
Creating data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage'
Combining data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage'
Deleting combined data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Combining data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
3rd process (get mixed up with 2st one)
Erasing data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Creating data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage'
Combining data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage'
Deleting combined data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46132.615372'
Combining data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
Opening data file '/home/mdk/clones/coverage-reproducer/.coverage'
Deleting combined data file '/home/mdk/clones/coverage-reproducer/.coverage.seraph.46133.288847'
my test script
export COVERAGE_DEBUG=dataio
/tmp/3.6/bin/pytest --cov-report term-missing --cov-fail-under=100 --cov src/ > 1.log 2>1.err &
/tmp/3.7/bin/pytest --cov-report term-missing --cov-fail-under=100 --cov src/ > 2.log 2>2.err &
/tmp/3.8/bin/pytest --cov-report term-missing --cov-fail-under=100 --cov src/ > 3.log 2>3.err

Looks like the problem tighten up around pytest-cov using coverage combine, which can't really work when multiple process are spawning files in parallel.

Reproducer, which I run using while tox -p all; do :; done and wait (it can take from a few seconds to ... I don't know sorry).

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Following up on this one, I successfully use coverage in parallel since enough time to tell it's stable, but without pytest-cov which uses an intermediate combine step (see previous message).

An example using tox to run pytest and coverage for multiple Python versions in parallel and then combining the result can be found here:

I think this issue can be closed.

Carreau added a commit to Carreau/zarr-python that referenced this issue Dec 16, 2020
Carreau added a commit to Carreau/zarr-python that referenced this issue Dec 16, 2020
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nedbat commented Jan 20, 2022

I believe this is now fixed in commit b41be3f

@nedbat nedbat closed this as completed Jan 20, 2022
@nedbat nedbat added the fixed label Jan 20, 2022
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nedbat commented Jan 25, 2022

This is now released as part of coverage 6.3.

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coverage==6.3.1 no errors.
Thank you

netbsd-srcmastr pushed a commit to NetBSD/pkgsrc that referenced this issue Aug 24, 2022
Version 6.4.4 — 2022-08-16

- Wheels are now provided for Python 3.11.

.. _changes_6-4-3:

Version 6.4.3 — 2022-08-06

- Fix a failure when combining data files if the file names contained
  glob-like patterns (`pull 1405`_).  Thanks, Michael Krebs and Benjamin

- Fix a messaging failure when combining Windows data files on a different
  drive than the current directory. (`pull 1430`_, fixing `issue 1428`_).
  Thanks, Lorenzo Micò.

- Fix path calculations when running in the root directory, as you might do in
  a Docker container: `pull 1403`_, thanks Arthur Rio.

- Filtering in the HTML report wouldn't work when reloading the index page.
  This is now fixed (`pull 1413`_).  Thanks, Marc Legendre.

- Fix a problem with Cython code measurement (`pull 1347`_, fixing `issue
  972`_).  Thanks, Matus Valo.

.. _issue 972: nedbat/coveragepy#972
.. _pull 1347: nedbat/coveragepy#1347
.. _pull 1403: nedbat/coveragepy#1403
.. _pull 1405: nedbat/coveragepy#1405
.. _pull 1413: nedbat/coveragepy#1413
.. _issue 1428: nedbat/coveragepy#1428
.. _pull 1430: nedbat/coveragepy#1430

.. _changes_6-4-2:

Version 6.4.2 — 2022-07-12

- Updated for a small change in Python 3.11.0 beta 4: modules now start with a
  line with line number 0, which is ignored.  This line cannnot be executed, so
  coverage totals were thrown off.  This line is now ignored by,
  but this also means that truly empty modules (like ````) have no
  lines in them, rather than one phantom line.  Fixes `issue 1419`_.

- Internal debugging data added to sys.modules is now an actual module, to
  avoid confusing code that examines everything in sys.modules.  Thanks,
  Yilei Yang (`pull 1399`_).

.. _pull 1399: nedbat/coveragepy#1399
.. _issue 1419: nedbat/coveragepy#1419

.. _changes_6-4-1:

Version 6.4.1 — 2022-06-02

- Greatly improved performance on PyPy, and other environments that need the
  pure Python trace function.  Thanks, Carl Friedrich Bolz-Tereick (`pull
  1381`_ and `pull 1388`_).  Slightly improved performance when using the C
  trace function, as most environments do.  Closes `issue 1339`_.

- The conditions for using tomllib from the standard library have been made
  more precise, so that 3.11 alphas will continue to work. Closes `issue

.. _issue 1339: nedbat/coveragepy#1339
.. _pull 1381: nedbat/coveragepy#1381
.. _pull 1388: nedbat/coveragepy#1388
.. _issue 1390: nedbat/coveragepy#1390

.. _changes_64:

Version 6.4 — 2022-05-22

- A new setting, :ref:`config_run_sigterm`, controls whether a SIGTERM signal
  handler is used.  In 6.3, the signal handler was always installed, to capture
  data at unusual process ends.  Unfortunately, this introduced other problems
  (see `issue 1310`_).  Now the signal handler is only used if you opt-in by
  setting ``[run] sigterm = true``.

- Small changes to the HTML report:

  - Added links to next and previous file, and more keyboard shortcuts: ``[``
    and ``]`` for next file and previous file; ``u`` for up to the index; and
    ``?`` to open/close the help panel.  Thanks, `J. M. F. Tsang
    <pull 1364_>`_.

  - The timestamp and version are displayed at the top of the report.  Thanks,
    `Ammar Askar <pull 1354_>`_. Closes `issue 1351`_.

- A new debug option ``debug=sqldata`` adds more detail to ``debug=sql``,
  logging all the data being written to the database.

- Previously, running ``coverage report`` (or any of the reporting commands) in
  an empty directory would create a .coverage data file.  Now they do not,
  fixing `issue 1328`_.

- On Python 3.11, the ``[toml]`` extra no longer installs tomli, instead using
  tomllib from the standard library.  Thanks `Shantanu <pull 1359_>`_.

- In-memory CoverageData objects now properly update(), closing `issue 1323`_.

.. _issue 1310: nedbat/coveragepy#1310
.. _issue 1323: nedbat/coveragepy#1323
.. _issue 1328: nedbat/coveragepy#1328
.. _issue 1351: nedbat/coveragepy#1351
.. _pull 1354: nedbat/coveragepy#1354
.. _pull 1359: nedbat/coveragepy#1359
.. _pull 1364: nedbat/coveragepy#1364

.. _changes_633:

Version 6.3.3 — 2022-05-12

- Fix: now builds successfully on CPython 3.11 (3.11.0b1) again.
  Closes `issue 1367`_.  Some results for generators may have changed.

.. _issue 1367: nedbat/coveragepy#1367

.. _changes_632:

Version 6.3.2 — 2022-02-20

- Fix: adapt to pypy3.9's decorator tracing behavior.  It now traces function
  decorators like CPython 3.8: both the @-line and the def-line are traced.
  Fixes `issue 1326`_.

- Debug: added ``pybehave`` to the list of :ref:`coverage debug <cmd_debug>`
  and :ref:`cmd_run_debug` options.

- Fix: show an intelligible error message if ``--concurrency=multiprocessing``
  is used without a configuration file.  Closes `issue 1320`_.

.. _issue 1320: nedbat/coveragepy#1320
.. _issue 1326: nedbat/coveragepy#1326

.. _changes_631:

Version 6.3.1 — 2022-02-01

- Fix: deadlocks could occur when terminating processes.  Some of these
  deadlocks (described in `issue 1310`_) are now fixed.

- Fix: a signal handler was being set from multiple threads, causing an error:
  "ValueError: signal only works in main thread".  This is now fixed, closing
  `issue 1312`_.

- Fix: ``--precision`` on the command-line was being ignored while considering
  ``--fail-under``.  This is now fixed, thanks to
  `Marcelo Trylesinski <pull 1317_>`_.

- Fix: releases no longer provide 3.11.0-alpha wheels. uses CPython
  internal fields which are moving during the alpha phase. Fixes `issue 1316`_.

.. _issue 1310: nedbat/coveragepy#1310
.. _issue 1312: nedbat/coveragepy#1312
.. _issue 1316: nedbat/coveragepy#1316
.. _pull 1317: nedbat/coveragepy#1317

.. _changes_63:

Version 6.3 — 2022-01-25

- Feature: Added the ``lcov`` command to generate reports in LCOV format.
  Thanks, `Bradley Burns <pull 1289_>`_. Closes issues `587 <issue 587_>`_
  and `626 <issue 626_>`_.

- Feature: the coverage data file can now be specified on the command line with
  the ``--data-file`` option in any command that reads or writes data.  This is
  in addition to the existing ``COVERAGE_FILE`` environment variable.  Closes
  `issue 624`_. Thanks, `Nikita Bloshchanevich <pull 1304_>`_.

- Feature: coverage measurement data will now be written when a SIGTERM signal
  is received by the process.  This includes
  :meth:`Process.terminate <python:multiprocessing.Process.terminate>`,
  and other ways to terminate a process.  Currently this is only on Linux and
  Mac; Windows is not supported.  Fixes `issue 1307`_.

- Dropped support for Python 3.6, which reached end-of-life on 2021-12-23.

- Updated Python 3.11 support to 3.11.0a4, fixing `issue 1294`_.

- Fix: the coverage data file is now created in a more robust way, to avoid
  problems when multiple processes are trying to write data at once. Fixes
  issues `1303 <issue 1303_>`_ and `883 <issue 883_>`_.

- Fix: a .gitignore file will only be written into the HTML report output
  directory if the directory is empty.  This should prevent certain unfortunate
  accidents of writing the file where it is not wanted.

- Releases now have MacOS arm64 wheels for Apple Silicon, fixing `issue 1288`_.

.. _issue 587: nedbat/coveragepy#587
.. _issue 624: nedbat/coveragepy#624
.. _issue 626: nedbat/coveragepy#626
.. _issue 883: nedbat/coveragepy#883
.. _issue 1288: nedbat/coveragepy#1288
.. _issue 1294: nedbat/coveragepy#1294
.. _issue 1303: nedbat/coveragepy#1303
.. _issue 1307: nedbat/coveragepy#1307
.. _pull 1289: nedbat/coveragepy#1289
.. _pull 1304: nedbat/coveragepy#1304

.. _changes_62:

Version 6.2 — 2021-11-26

- Feature: Now the ``--concurrency`` setting can now have a list of values, so
  that threads and another lightweight threading package can be measured
  together, such as ``--concurrency=gevent,thread``.  Closes `issue 1012`_ and
  `issue 1082`_.

- Fix: A module specified as the ``source`` setting is imported during startup,
  before the user program imports it.  This could cause problems if the rest of
  the program isn't ready yet.  For example, `issue 1203`_ describes a Django
  setting that is accessed before settings have been configured.  Now the early
  import is wrapped in a try/except so errors then don't stop execution.

- Fix: A colon in a decorator expression would cause an exclusion to end too
  early, preventing the exclusion of the decorated function. This is now fixed.

- Fix: The HTML report now will not overwrite a .gitignore file that already
  exists in the HTML output directory (follow-on for `issue 1244`_).

- API: The exceptions raised by have been specialized, to provide
  finer-grained catching of exceptions by third-party code.

- API: Using ``suffix=False`` when constructing a Coverage object with
  multiprocessing wouldn't suppress the data file suffix (`issue 989`_).  This
  is now fixed.

- Debug: The ``coverage debug data`` command will now sniff out combinable data
  files, and report on all of them.

- Debug: The ``coverage debug`` command used to accept a number of topics at a
  time, and show all of them, though this was never documented.  This no longer
  works, to allow for command-line options in the future.

.. _issue 989: nedbat/coveragepy#989
.. _issue 1012: nedbat/coveragepy#1012
.. _issue 1082: nedbat/coveragepy#1082
.. _issue 1203: nedbat/coveragepy#1203

.. _changes_612:

Version 6.1.2 — 2021-11-10

- Python 3.11 is supported (tested with 3.11.0a2).  One still-open issue has to
  do with `exits through with-statements <issue 1270_>`_.

- Fix: When remapping file paths through the ``[paths]`` setting while
  combining, the ``[run] relative_files`` setting was ignored, resulting in
  absolute paths for remapped file names (`issue 1147`_).  This is now fixed.

- Fix: Complex conditionals over excluded lines could have incorrectly reported
  a missing branch (`issue 1271`_). This is now fixed.

- Fix: More exceptions are now handled when trying to parse source files for
  reporting.  Problems that used to terminate can now be handled
  with ``[report] ignore_errors``.  This helps with plugins failing to read
  files (`django_coverage_plugin issue 78`_).

- Fix: Removed another vestige of jQuery from the source tarball
  (`issue 840`_).

- Fix: Added a default value for a new-to-6.x argument of an internal class.
  This unsupported class is being used by coveralls (`issue 1273`_). Although
  I'd rather not "fix" unsupported interfaces, it's actually nicer with a
  default value.

.. _django_coverage_plugin issue 78: nedbat/django_coverage_plugin#78
.. _issue 1147: nedbat/coveragepy#1147
.. _issue 1270: nedbat/coveragepy#1270
.. _issue 1271: nedbat/coveragepy#1271
.. _issue 1273: nedbat/coveragepy#1273

.. _changes_611:

Version 6.1.1 — 2021-10-31

- Fix: The sticky header on the HTML report didn't work unless you had branch
  coverage enabled. This is now fixed: the sticky header works for everyone.
  (Do people still use coverage without branch measurement!? j/k)

- Fix: When using explicitly declared namespace packages, the "already imported
  a file that will be measured" warning would be issued (`issue 888`_).  This
  is now fixed.

.. _issue 888: nedbat/coveragepy#888

.. _changes_61:

Version 6.1 — 2021-10-30

- Deprecated: The ``annotate`` command and the ``Coverage.annotate`` function
  will be removed in a future version, unless people let me know that they are
  using it.  Instead, the ``html`` command gives better-looking (and more
  accurate) output, and the ``report -m`` command will tell you line numbers of
  missing lines.  Please get in touch if you have a reason to use ``annotate``
  over those better options:

- Feature: Coverage now sets an environment variable, ``COVERAGE_RUN`` when
  running your code with the ``coverage run`` command.  The value is not
  important, and may change in the future.  Closes `issue 553`_.

- Feature: The HTML report pages for Python source files now have a sticky
  header so the file name and controls are always visible.

- Feature: The ``xml`` and ``json`` commands now describe what they wrote

- Feature: The ``html``, ``combine``, ``xml``, and ``json`` commands all accept
  a ``-q/--quiet`` option to suppress the messages they write to stdout about
  what they are doing (`issue 1254`_).

- Feature: The ``html`` command writes a ``.gitignore`` file into the HTML
  output directory, to prevent the report from being committed to git.  If you
  want to commit it, you will need to delete that file.  Closes `issue 1244`_.

- Feature: Added support for PyPy 3.8.

- Fix: More generated code is now excluded from measurement.  Code such as
  `attrs`_ boilerplate, or doctest code, was being measured though the
  synthetic line numbers meant they were never reported.  Once Cython was
  involved though, the generated .so files were parsed as Python, raising
  syntax errors, as reported in `issue 1160`_.  This is now fixed.

- Fix: When sorting human-readable names, numeric components are sorted
  correctly: will appear after  This applies to file names,
  module names, environment variables, and test contexts.

- Performance: Branch coverage measurement is faster, though you might only
  notice on code that is executed many times, such as long-running loops.

- Build: jQuery is no longer used or vendored (`issue 840`_ and `issue 1118`_).
  Huge thanks to Nils Kattenbeck (septatrix) for the conversion to vanilla
  JavaScript in `pull request 1248`_.

.. _issue 553: nedbat/coveragepy#553
.. _issue 840: nedbat/coveragepy#840
.. _issue 1118: nedbat/coveragepy#1118
.. _issue 1160: nedbat/coveragepy#1160
.. _issue 1244: nedbat/coveragepy#1244
.. _pull request 1248: nedbat/coveragepy#1248
.. _issue 1254: nedbat/coveragepy#1254
.. _attrs:

.. _changes_602:

Version 6.0.2 — 2021-10-11

- Namespace packages being measured weren't properly handled by the new code
  that ignores third-party packages. If the namespace package was installed, it
  was ignored as a third-party package.  That problem (`issue 1231`_) is now

- Packages named as "source packages" (with ``source``, or ``source_pkgs``, or
  pytest-cov's ``--cov``) might have been only partially measured.  Their
  top-level statements could be marked as unexecuted, because they were
  imported by before measurement began (`issue 1232`_).  This is
  now fixed, but the package will be imported twice, once by, then
  again by your test suite.  This could cause problems if importing the package
  has side effects.

- The :meth:`.CoverageData.contexts_by_lineno` method was documented to return
  a dict, but was returning a defaultdict.  Now it returns a plain dict.  It
  also no longer returns negative numbered keys.

.. _issue 1231: nedbat/coveragepy#1231
.. _issue 1232: nedbat/coveragepy#1232

.. _changes_601:

Version 6.0.1 — 2021-10-06

- In 6.0, the exceptions moved from coverage.misc to
  coverage.exceptions. These exceptions are not part of the public supported
  API, CoverageException is. But a number of other third-party packages were
  importing the exceptions from coverage.misc, so they are now available from
  there again (`issue 1226`_).

- Changed an internal detail of how tomli is imported, so that tomli can use for their own test suite (`issue 1228`_).

- Defend against an obscure possibility under code obfuscation, where a
  function can have an argument called "self", but no local named "self"
  (`pull request 1210`_).  Thanks, Ben Carlsson.

.. _pull request 1210: nedbat/coveragepy#1210
.. _issue 1226: nedbat/coveragepy#1226
.. _issue 1228: nedbat/coveragepy#1228

.. _changes_60:

Version 6.0 — 2021-10-03

- The ``coverage html`` command now prints a message indicating where the HTML
  report was written.  Fixes `issue 1195`_.

- The ``coverage combine`` command now prints messages indicating each data
  file being combined.  Fixes `issue 1105`_.

- The HTML report now includes a sentence about skipped files due to
  ``skip_covered`` or ``skip_empty`` settings.  Fixes `issue 1163`_.

- Unrecognized options in the configuration file are no longer errors. They are
  now warnings, to ease the use of coverage across versions.  Fixes `issue

- Fix handling of exceptions through context managers in Python 3.10. A missing
  exception is no longer considered a missing branch from the with statement.
  Fixes `issue 1205`_.

- Fix another rarer instance of "Error binding parameter 0 - probably
  unsupported type." (`issue 1010`_).

- Creating a directory for the coverage data file now is safer against
  conflicts when two coverage runs happen simultaneously (`pull 1220`_).
  Thanks, Clément Pit-Claudel.

.. _issue 1035: nedbat/coveragepy#1035
.. _issue 1105: nedbat/coveragepy#1105
.. _issue 1163: nedbat/coveragepy#1163
.. _issue 1195: nedbat/coveragepy#1195
.. _issue 1205: nedbat/coveragepy#1205
.. _pull 1220: nedbat/coveragepy#1220

.. _changes_60b1:

Version 6.0b1 — 2021-07-18

- Dropped support for Python 2.7, PyPy 2, and Python 3.5.

- Added support for the Python 3.10 ``match/case`` syntax.

- Data collection is now thread-safe.  There may have been rare instances of
  exceptions raised in multi-threaded programs.

- Plugins (like the `Django coverage plugin`_) were generating "Already
  imported a file that will be measured" warnings about Django itself.  These
  have been fixed, closing `issue 1150`_.

- Warnings generated by are now real Python warnings.

- Using ``--fail-under=100`` with coverage near 100% could result in the
  self-contradictory message :code:`total of 100 is less than fail-under=100`.
  This bug (`issue 1168`_) is now fixed.

- The ``COVERAGE_DEBUG_FILE`` environment variable now accepts ``stdout`` and
  ``stderr`` to write to those destinations.

- TOML parsing now uses the `tomli`_ library.

- Some minor changes to usually invisible details of the HTML report:

  - Use a modern hash algorithm when fingerprinting, for high-security
    environments (`issue 1189`_).  When generating the HTML report, we save the
    hash of the data, to avoid regenerating an unchanged HTML page. We used to
    use MD5 to generate the hash, and now use SHA-3-256.  This was never a
    security concern, but security scanners would notice the MD5 algorithm and
    raise a false alarm.

  - Change how report file names are generated, to avoid leading underscores
    (`issue 1167`_), to avoid rare file name collisions (`issue 584`_), and to
    avoid file names becoming too long (`issue 580`_).

.. _Django coverage plugin:
.. _issue 580: nedbat/coveragepy#580
.. _issue 584: nedbat/coveragepy#584
.. _issue 1150: nedbat/coveragepy#1150
.. _issue 1167: nedbat/coveragepy#1167
.. _issue 1168: nedbat/coveragepy#1168
.. _issue 1189: nedbat/coveragepy#1189
.. _tomli:

.. _changes_56b1:

Version 5.6b1 — 2021-04-13

Note: 5.6 final was never released. These changes are part of 6.0.

- Third-party packages are now ignored in coverage reporting.  This solves a
  few problems:

  - Coverage will no longer report about other people's code (`issue 876`_).
    This is true even when using ``--source=.`` with a venv in the current

  - Coverage will no longer generate "Already imported a file that will be
    measured" warnings about coverage itself (`issue 905`_).

- The HTML report uses j/k to move up and down among the highlighted chunks of
  code.  They used to highlight the current chunk, but 5.0 broke that behavior.
  Now the highlighting is working again.

- The JSON report now includes ``percent_covered_display``, a string with the
  total percentage, rounded to the same number of decimal places as the other
  reports' totals.

.. _issue 876: nedbat/coveragepy#876
.. _issue 905: nedbat/coveragepy#905
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