Re: [PATCH] kunit: tool: yield output from run_kernel in real time

[David Gow]

On Tue, Oct 5, 2021 at 7:46 AM Daniel Latypov <dlatypov@xxxxxxxxxx> wrote:
>
> On Mon, Oct 4, 2021 at 4:34 PM 'David Gow' via KUnit Development
> <kunit-dev@xxxxxxxxxxxxxxxx> wrote:
> >
> > On Tue, Oct 5, 2021 at 1:01 AM Daniel Latypov <dlatypov@xxxxxxxxxx> wrote:
> > >
> > > Currently, `run_kernel()` dumps all the kernel output to a file
> > > (.kunit/test.log) and then opens the file and yields it to callers.
> > > This made it easier to respect the requested timeout, if any.
> > >
> > > But it means that we can't yield the results in real time, either to the
> > > parser or to stdout (if --raw_output is set).
> > >
> > > This change spins up a background thread to enforce the timeout, which
> > > allows us to yield the kernel output in real time, while also copying it
> > > to the .kunit/test.log file.
> > > It's also careful to ensure that the .kunit/test.log file is complete,
> > > even in the kunit_parser throws an exception/otherwise doesn't consume
> > > every line, see the new `finally` block and unit test.
> > >
> > > For example:
> > >
> > > $ ./tools/testing/kunit/kunit.py run --arch=x86_64 --raw_output
> > > <configure + build steps>
> > > ...
> > > <can now see output from QEMU in real time>
> > >
> > > This does not currently have a visible effect when --raw_output is not
> > > passed, as kunit_parser.py currently only outputs everything at the end.
> > > But that could change, and this patch is a necessary step towards
> > > showing parsed test results in real time.
> > >
> > > Signed-off-by: Daniel Latypov <dlatypov@xxxxxxxxxx>
> > > ---
> > >  tools/testing/kunit/kunit_kernel.py    | 73 +++++++++++++++-----------
> > >  tools/testing/kunit/kunit_tool_test.py | 17 ++++++
> > >  2 files changed, 60 insertions(+), 30 deletions(-)
> > >
> > > diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
> > > index 2c6f916ccbaf..b8cba8123aa3 100644
> > > --- a/tools/testing/kunit/kunit_kernel.py
> > > +++ b/tools/testing/kunit/kunit_kernel.py
> > > @@ -12,7 +12,8 @@ import subprocess
> > >  import os
> > >  import shutil
> > >  import signal
> > > -from typing import Iterator, Optional, Tuple
> > > +import threading
> > > +from typing import Iterator, List, Optional, Tuple
> > >
> > >  from contextlib import ExitStack
> > >
> > > @@ -103,8 +104,8 @@ class LinuxSourceTreeOperations(object):
> > >                 if stderr:  # likely only due to build warnings
> > >                         print(stderr.decode())
> > >
> > > -       def run(self, params, timeout, build_dir, outfile) -> None:
> > > -               pass
> > > +       def start(self, params: List[str], build_dir: str) -> subprocess.Popen:
> > > +               raise RuntimeError('not implemented!')
> > >
> > >
> > >  class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
> > > @@ -123,7 +124,7 @@ class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
> > >                 kconfig.parse_from_string(self._kconfig)
> > >                 base_kunitconfig.merge_in_entries(kconfig)
> > >
> > > -       def run(self, params, timeout, build_dir, outfile):
> > > +       def start(self, params: List[str], build_dir: str) -> subprocess.Popen:
> > >                 kernel_path = os.path.join(build_dir, self._kernel_path)
> > >                 qemu_command = ['qemu-system-' + self._qemu_arch,
> > >                                 '-nodefaults',
> > > @@ -134,18 +135,10 @@ class LinuxSourceTreeOperationsQemu(LinuxSourceTreeOperations):
> > >                                 '-nographic',
> > >                                 '-serial stdio'] + self._extra_qemu_params
> > >                 print('Running tests with:\n$', ' '.join(qemu_command))
> > > -               with open(outfile, 'w') as output:
> > > -                       process = subprocess.Popen(' '.join(qemu_command),
> > > -                                                  stdin=subprocess.PIPE,
> > > -                                                  stdout=output,
> > > -                                                  stderr=subprocess.STDOUT,
> > > -                                                  text=True, shell=True)
> > > -               try:
> > > -                       process.wait(timeout=timeout)
> > > -               except Exception as e:
> > > -                       print(e)
> > > -                       process.terminate()
> > > -               return process
> > > +               return subprocess.Popen(' '.join(qemu_command),
> > > +                                          stdout=subprocess.PIPE,
> > > +                                          stderr=subprocess.STDOUT,
> > > +                                          text=True, shell=True)
> > >
> > >  class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
> > >         """An abstraction over command line operations performed on a source tree."""
> > > @@ -175,17 +168,13 @@ class LinuxSourceTreeOperationsUml(LinuxSourceTreeOperations):
> > >                 kunit_parser.print_with_timestamp(
> > >                         'Starting Kernel with all configs takes a few minutes...')
> > >
> > > -       def run(self, params, timeout, build_dir, outfile):
> > > +       def start(self, params: List[str], build_dir: str) -> subprocess.Popen:
> > >                 """Runs the Linux UML binary. Must be named 'linux'."""
> > >                 linux_bin = get_file_path(build_dir, 'linux')
> > > -               outfile = get_outfile_path(build_dir)
> > > -               with open(outfile, 'w') as output:
> > > -                       process = subprocess.Popen([linux_bin] + params,
> > > -                                                  stdin=subprocess.PIPE,
> >
> > This breaks --raw_output under UML for me. Including the
> > stdin=subprocess.PIPE again seems to fix it.
>
> Can you give an example of what it does?
>
> I don't see any issues with --raw_output under UML with the patch as-is.
> I was mainly testing this with UML, and I must have ran it some 10s of
> times, so I'm a bit surprised.
>
> On an earlier version, I saw some mangling of --raw_output (\n was
> missing), but that went away after some revisions.
>

Yeah, that's the sort of thing I'm seeing: \n being treated as just a
new line (without the carriage return).
It happens pretty consistently, though sometimes the text wraps and
sometimes (well, once) everything gets forced into the last column of
the terminal. I've not been able to get it to work at all without
having stdin be subprocess.PIPE.

It occurs both under tmux and not, and under Konsole and xterm, so it
doesn't appear to be specific to any given terminal implementation.
Still occurs even after running 'reset', and with a clean build.
QEMU-based --raw_output works fine.


> >
> > > -                                                  stdout=output,
> > > -                                                  stderr=subprocess.STDOUT,
> > > -                                                  text=True)
> > > -                       process.wait(timeout)
> > > +               return subprocess.Popen([linux_bin] + params,
> > > +                                          stdout=subprocess.PIPE,
> > > +                                          stderr=subprocess.STDOUT,
> > > +                                          text=True)
> > >
> > >  def get_kconfig_path(build_dir) -> str:
> > >         return get_file_path(build_dir, KCONFIG_PATH)
> > > @@ -330,12 +319,36 @@ class LinuxSourceTree(object):
> > >                 args.extend(['mem=1G', 'console=tty', 'kunit_shutdown=halt'])
> > >                 if filter_glob:
> > >                         args.append('kunit.filter_glob='+filter_glob)
> > > -               outfile = get_outfile_path(build_dir)
> > > -               self._ops.run(args, timeout, build_dir, outfile)
> > > -               subprocess.call(['stty', 'sane'])
> > > -               with open(outfile, 'r') as file:
> > > -                       for line in file:
> > > +
> > > +               process = self._ops.start(args, build_dir)
> > > +               assert process.stdout is not None  # tell mypy it's set
> > > +
> > > +               # Enforce the timeout in a background thread.
> > > +               def _wait_proc():
> > > +                       try:
> > > +                               process.wait(timeout=timeout)
> > > +                       except Exception as e:
> > > +                               print(e)
> > > +                               process.terminate()
> > > +                               process.wait()
> > > +               waiter = threading.Thread(target=_wait_proc)
> > > +               waiter.start()
> > > +
> > > +               output = open(get_outfile_path(build_dir), 'w')
> > > +               try:
> > > +                       # Tee the output to the file and to our caller in real time.
> > > +                       for line in process.stdout:
> > > +                               output.write(line)
> > >                                 yield line
> > > +               # This runs even if our caller doesn't consume every line.
> > > +               finally:
> > > +                       # Flush any leftover output to the file
> > > +                       output.write(process.stdout.read())
> > > +                       output.close()
> > > +                       process.stdout.close()
> > > +
> > > +                       waiter.join()
> > > +                       subprocess.call(['stty', 'sane'])
> > >
> > >         def signal_handler(self, sig, frame) -> None:
> > >                 logging.error('Build interruption occurred. Cleaning console.')
> > > diff --git a/tools/testing/kunit/kunit_tool_test.py b/tools/testing/kunit/kunit_tool_test.py
> > > index 619c4554cbff..f9a7398a9584 100755
> > > --- a/tools/testing/kunit/kunit_tool_test.py
> > > +++ b/tools/testing/kunit/kunit_tool_test.py
> > > @@ -14,6 +14,7 @@ import tempfile, shutil # Handling test_tmpdir
> > >  import itertools
> > >  import json
> > >  import signal
> > > +import subprocess
> > >  import os
> > >
> > >  import kunit_config
> > > @@ -291,6 +292,22 @@ class LinuxSourceTreeTest(unittest.TestCase):
> > >                                 pass
> > >                         tree = kunit_kernel.LinuxSourceTree('', kunitconfig_path=dir)
> > >
> > > +       def test_run_kernel_hits_exception(self):
> > > +               def fake_start(unused_args, unused_build_dir):
> > > +                       return subprocess.Popen(['echo "hi\nbye"'], shell=True, text=True, stdout=subprocess.PIPE)
> > > +
> > > +               with tempfile.TemporaryDirectory('') as build_dir:
> > > +                       tree = kunit_kernel.LinuxSourceTree(build_dir, load_config=False)
> > > +                       mock.patch.object(tree._ops, 'start', side_effect=fake_start).start()
> > > +
> > > +                       with self.assertRaises(ValueError):
> > > +                               for line in tree.run_kernel(build_dir=build_dir):
> > > +                                       self.assertEqual(line, 'hi\n')
> > > +                                       raise ValueError('uh oh, did not read all output')
> > > +
> > > +                       with open(kunit_kernel.get_outfile_path(build_dir), 'rt') as outfile:
> > > +                               self.assertEqual(outfile.read(), 'hi\nbye\n', msg='Missing some output')
> > > +
> > >         # TODO: add more test cases.
> > >
> > >
> > >
> > > base-commit: 3b29021ddd10cfb6b2565c623595bd3b02036f33
> > > --
> > > 2.33.0.800.g4c38ced690-goog
> > >
> >
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