I've aborted the reset job. link to the reset job log:
https://pantheon.corp.google.com/storage/browser/chromeos-autotest-results/hosts/chromeos1-row2-rack4-host3/489895-reset/20160104005649/debug/?debugUI=DEVELOPERS

04/01 00:56:54.734 DEBUG|      abstract_ssh:0843| Started ssh tunnel, local = 39392 remote = 9992, pid = 14127
04/01 00:56:54.740 DEBUG|    chameleon_host:0118| Connection is not ready yet ...
04/01 00:56:54.842 DEBUG|    chameleon_host:0118| Connection is not ready yet ...

It seems to be related to ssh tunnel and chameleon connection, we should have a timeout setting on that.

It's unusual, actually chameleon has the timeout setting,

success = utils.wait_for_value(
        _create_connection, expected_value=True, timeout_sec=30)
if not success:
        raise ChameleonHostError('Can not connect to Chameleon')


I test it in chromeos2-row1-rack4-host4 if the connection is finally failed due to 'Connection is not ready yet'. The logging is like:

04/01 20:39:08.824 DEBUG|      abstract_ssh:0835| Full tunnel command: /usr/bin/ssh -a -x -n -N -q -L 36957:localhost:9992 -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null -o BatchMode=yes -o ConnectTimeout=30 -o ServerAliveInterval=300 -l root -p 22 chromeos2-row1-rack4-host4-chameleon.cros
04/01 20:39:08.827 DEBUG|      abstract_ssh:0843| Started ssh tunnel, local = 36957 remote = 9992, pid = 1933
04/01 20:39:08.828 DEBUG|    chameleon_host:0120| Connection is not ready yet ...
04/01 20:39:08.928 DEBUG|    chameleon_host:0120| Connection is not ready yet ...
...
04/01 20:39:38.749 DEBUG|    chameleon_host:0120| Connection is not ready yet ...
04/01 20:39:38.850 DEBUG|    chameleon_host:0120| Connection is not ready yet ...
04/01 20:39:38.850 ERROR|    chameleon_host:0102| Error in creating connection through tunnel.
Traceback (most recent call last):
  File "/build/veyron_jerry/usr/local/build/autotest/server/hosts/chameleon_host.py", line 98, in _create_connection_through_tunnel
    self._wait_for_connection_established()
  File "/build/veyron_jerry/usr/local/build/autotest/server/hosts/chameleon_host.py", line 130, in _wait_for_connection_established
    raise ChameleonHostError('Can not connect to Chameleon')

I can't figure out why the logging of this device is interrupted. Any ideas?

Runninng now. Thanks