Mariusz Okulanis created HADOOP-18038:
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Summary: "hdfs --daemon start" command may write invalid PID to
file
Key: HADOOP-18038
URL: https://issues.apache.org/jira/browse/HADOOP-18038
Project: Hadoop Common
Issue Type: Bug
Components: scripts
Affects Versions: 3.3.2
Reporter: Mariusz Okulanis
Starting a daemon with hdfs --daemon start ... (and also yarn --daemon start
...) might result in writing invalid PID to PIDfile.
Root cause of the issue is a fact that both daemon launching bash functions -
hadoop_start_daemon and hadoop_start_daemon_wrapper - are concurrently writing
different PIDs to the same file, and only PID written by
hadoop_start_daemon_wrapper is correct. Order of those writes is weakly
synchronised (with hardcoded 5s timeout). Under specific circumstances (like
heavy CPU load) this ordering might not be preserved resulting in invalid PID
ending up in PIDfile.
Possible solution: It seems that it's unnecessary for hadoop_start_daemon to
write to pidfile if it's being called from hadoop_start_daemon_wrapper - it
should skip this step in this scenario.
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