Hari Sekhon created AMBARI-8768:
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Summary: Ambari agent Heartbeat lost when df hangs (NFS gateway),
also prevents proper re-initialization of agent upon restart
Key: AMBARI-8768
URL: https://issues.apache.org/jira/browse/AMBARI-8768
Project: Ambari
Issue Type: Bug
Components: ambari-agent
Affects Versions: 1.7.0
Environment: HDP 2.1
Reporter: Hari Sekhon
Ambari agent is succeptible to hanging when the 'df' command blocks. This
causes loss of heartbeat and manageability. I've found this has happened with
NFS gateway's HDFS mount point blocking when HDFS isn't available (we had set
the NFS hard option on the mount point but then realized that wasn't a good
idea as not everyone's processes and scripts will handle failure gracefully and
retry properly).
When restarting the agent it also leaves the df process bound to point 8670
which requires manually killing that in order to get the ambari agent to
restart and bind successfully, but even then you'll see a hang at this point
after connecting to the 8440 ca and the agent never fully initializes so the
heartbeat still never comes back.
The df command should be either in another thread non-blocking the main
heartbeat and management functions or should have a timeout set on the command
execution to prevent this issue.
Regards,
Hari Sekhon
http://www.linkedin.com/in/harisekhon
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