Tao Yang created HDFS-14575:
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Summary: LeaseRenewer#daemon threads leak in DFSClient
Key: HDFS-14575
URL: https://issues.apache.org/jira/browse/HDFS-14575
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Tao Yang
Currently LeaseRenewer (and its daemon thread) without clients should be
terminated after a grace period which defaults to 60 seconds. A race condition
may happen when a new request is coming just after LeaseRenewer expired.
Reproduce this race condition:
# Client#1 creates File#1: creates LeaseRenewer#1 and starts Daemon#1 thread,
after a few seconds, File#1 is closed , there is no clients in LeaseRenewer#1
now.
# 60 seconds (grace period) later, LeaseRenewer#1 just expires but daemon#1
thread is still in sleep, Client#1 creates File#2, lead to the creation of
Daemon#2.
# Daemon#1 is awake then exit, after that, LeaseRenewer#1 is removed from
factory.
# File#2 is closed after a few seconds, LeaseRenewer#2 is created since it
can’t get renewer from factory.
Daemon#2 thread leaks from now on, since Client#1 in it can never be removed
and it won't have a chance to stop.
To solve this problem, IIUIC, a simple way I think is to make sure that all
clients are cleared when LeaseRenewer is removed from factory. Please feel free
to give your suggestions. Thanks!
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