[jira] [Created] (AURORA-1799) Thermos does not handle low memory scenarios gracefully

["Zameer Manji (JIRA)" <ji...@apache.org>]

Zameer Manji created AURORA-1799:
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             Summary: Thermos does not handle low memory scenarios gracefully
                 Key: AURORA-1799
                 URL: https://issues.apache.org/jira/browse/AURORA-1799
             Project: Aurora
          Issue Type: Bug
            Reporter: Zameer Manji


Background:
In an environment where Aurora is used to launch Docker containers via the DockerContainerizer, it was observed that some tasks would not be killed.

What happened is that a task was allocated with a low amount of memory but demanded a lot. This caused the linux OOM killer to be invoked. Unlike the MesosContainerizer, the agent doesn't tear down the container when the OOM killer is invoked. Instead the OOM killer just kills a process in the container and thermos and mesos are unaware (unless a process directly launched by thermos is killed).

I observed in the scheduler logs that the scheduler was trying to kill a container every reconciliation period but it never died. The slave had the logs indicating it received the killTask RPC and forwarded it to Thermos.

The thermos logs had several entries like every hour:
{noformat}
I1018 20:39:18.102894 6 executor_base.py:45] Executor [aaeac4c8-2b2f-4351-874b-a16bea1b36b0-S147]: Activating kill manager.
I1018 20:39:18.103034 6 executor_base.py:45] Executor [aaeac4c8-2b2f-4351-874b-a16bea1b36b0-S147]: killTask returned.
I1018 21:39:17.859935 6 executor_base.py:45] Executor [aaeac4c8-2b2f-4351-874b-a16bea1b36b0-S147]: killTask got task_id: value: "<task_id>"
{noformat}

However, the tasks was never killed. Looking at the stderr of thermos I saw the following entries:
{noformat}
Logged from file resource.py, line 155
Traceback (most recent call last):
  File "/usr/lib/python2.7/logging/__init__.py", line 883, in emit
    self.flush()
  File "/usr/lib/python2.7/logging/__init__.py", line 843, in flush
    self.stream.flush()
IOError: [Errno 12] Cannot allocate memory
{noformat}

and 
{noformat}
Logged from file thermos_task_runner.py, line 171
Traceback (most recent call last):
  File "/root/.pex/install/twitter.common.exceptions-0.3.3-py2-none-any.whl.2a67b833b1517d179ef1c8dc6f2dac1023d51e3c/twitter.common.exceptions-0.3.3-py2-none-any.whl/twitter/common/exceptions/__init__.py", line 126, in _excepting_run

  File "apache/aurora/executor/status_manager.py", line 47, in run
  File "apache/aurora/executor/common/status_checker.py", line 97, in status
  File "apache/aurora/executor/thermos_task_runner.py", line 358, in status
  File "apache/aurora/executor/thermos_task_runner.py", line 186, in compute_status
  File "apache/aurora/executor/thermos_task_runner.py", line 136, in task_state
  File "apache/thermos/monitoring/monitor.py", line 118, in task_state
  File "apache/thermos/monitoring/monitor.py", line 114, in get_state
  File "apache/thermos/monitoring/monitor.py", line 77, in _apply_states
  File "/root/.pex/install/twitter.common.recordio-0.3.3-py2-none-any.whl.9f1e9394eca1bc33ad7d10ae3025301866824139/twitter.common.recordio-0.3.3-py2-none-any.whl/twitter/common/recordio/recordio.py", line 182, in try_read
    class InvalidTypeException(Error): pass
  File "/root/.pex/install/twitter.common.recordio-0.3.3-py2-none-any.whl.9f1e9394eca1bc33ad7d10ae3025301866824139/twitter.common.recordio-0.3.3-py2-none-any.whl/twitter/common/recordio/recordio.py", line 168, in read
    return RecordIO.Reader.do_read(self._fp, self._codec)
  File "/root/.pex/install/twitter.common.recordio-0.3.3-py2-none-any.whl.9f1e9394eca1bc33ad7d10ae3025301866824139/twitter.common.recordio-0.3.3-py2-none-any.whl/twitter/common/recordio/recordio.py", line 135, in do_read
    header = fp.read(RecordIO.RECORD_HEADER_SIZE)
  File "/root/.pex/install/twitter.common.recordio-0.3.3-py2-none-any.whl.9f1e9394eca1bc33ad7d10ae3025301866824139/twitter.common.recordio-0.3.3-py2-none-any.whl/twitter/common/recordio/filelike.py", line 81, in read
    return self._fp.read(length)
IOError: [Errno 12] Cannot allocate memory
{noformat}

It seems the regular avenues of reading checkpoints or logging data, thermos would get an IOError. Some part of twitter common installs an excepthook to log the exception, but we don't seem to do anything else.

I think we should probably install our own exception hook to send a {{LOST_TASK}} with the exception information instead of failing to kill the task.



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