[HDDS-377] Make the ScmClient closable and stop the started threads

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.2.1
• Component/s: SCM Client
• Assignee: Marton Elek
• Reporter: Marton Elek
• Created: 27/Aug/18 11:44
• Updated: 27/Aug/18 15:45
• Resolved: 27/Aug/18 15:20

Description

Current ScmClient class opens additional threads which won't be closed. For example SCMCLI can't stop because of this running thread:

"nioEventLoopGroup-2-1" #15 prio=10 os_prio=0 tid=0x00007f1c84c74800 nid=0x77f4 runnable [0x00007f1c52238000]
   java.lang.Thread.State: RUNNABLE
	at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
	at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
	at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:93)
	at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
	- locked <0x0000000771adf7b0> (a org.apache.ratis.shaded.io.netty.channel.nio.SelectedSelectionKeySet)
	- locked <0x0000000771ae12d8> (a java.util.Collections$UnmodifiableSet)
	- locked <0x0000000771ae1010> (a sun.nio.ch.EPollSelectorImpl)
	at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
	at org.apache.ratis.shaded.io.netty.channel.nio.SelectedSelectionKeySetSelector.select(SelectedSelectionKeySetSelector.java:62)
	at org.apache.ratis.shaded.io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:753)
	at org.apache.ratis.shaded.io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:409)
	at org.apache.ratis.shaded.io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
	at org.apache.ratis.shaded.io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
	at java.lang.Thread.run(Thread.java:745)

(Note this is netty, but the Grpc based xceiver also have some special threads).

I propose to make ScmClient auto-closable and stop the XceiverClientManager in case of close.