Blocked detector

[komuw]

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Now,

What(What have you changed?)

Why(Why did you change it?)

• fixes: validate that code inside Task.async_run is not blocking #4

References:

[komuw]

def BLOCKING_DISK_IO(the_broker) -> xyzabc.task.Task:
    class BlockingDiskIOTask(xyzabc.task.Task):
        async def async_run(self, *args, **kwargs):
            print()
            print("RUNNING BlockingDiskIOTask:")
            import subprocess

            subprocess.run(["dd", "if=/dev/zero", "of=/dev/null", "bs=500000", "count=1000000"])

    task = BlockingDiskIOTask(
        the_broker=the_broker,
        queue_name="BlockingDiskIOTask",
        eta=60.0,
        retries=3,
        log_id="myLogID",
        hook_metadata='{"email": "example@example.com"}',
    )
    return task

[komuw]

For the blocking disk IO task above, the TaskBlocker Watchdog generates this stack trace:

File "cli/cli.py", line 327, in <module>
    asyncio.run(async_main(), debug=True)

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/runners.py", line 43, in run
    return loop.run_until_complete(main)

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 555, in run_until_complete
    self.run_forever()

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 523, in run_forever
    self._run_once()

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/base_events.py", line 1750, in _run_once
    handle._run()

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/asyncio/events.py", line 88, in _run
    self._context.run(self._callback, *self._args)

  File "/Users/komuw/mystuff/xyzabc/xyzabc/worker.py", line 222, in consume_forever
    await self.run(*task_args, **task_kwargs)

  File "/Users/komuw/mystuff/xyzabc/xyzabc/worker.py", line 123, in run
    return_value = await self.the_task.async_run(*task_args, **task_kwargs)

  File "cli/cli.py", line 79, in async_run
    subprocess.run(["dd", "if=/dev/zero", "of=/dev/null", "bs=500000", "count=1000000"])

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 455, in run
    stdout, stderr = process.communicate(input, timeout=timeout)

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 912, in communicate
    self.wait()

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 971, in wait
    return self._wait(timeout=timeout)

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 1601, in _wait
    (pid, sts) = self._try_wait(0)

  File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 1559, in _try_wait
    (pid, sts) = os.waitpid(self.pid, wait_flags)