Threads get stuck on shutdown

[tilln]

When running in non-GUI mode with a few hundred monitoring instances (each with a single sampler row / command), threads get stuck when JMeter tries to shutdown the JVM (irrespective of increasing the jmeter.exit.check.pause) with log output like the following:

... end of run
The JVM should have exited but did not.
The following non-daemon threads are still running (DestroyJavaVM is OK):
Thread[Thread-430,5,main], stackTrace:java.lang.Object#wait
java.io.PipedInputStream#read
java.io.PipedInputStream#read
sun.nio.cs.StreamDecoder#readBytes
sun.nio.cs.StreamDecoder#implRead
sun.nio.cs.StreamDecoder#read
java.io.InputStreamReader#read
java.io.Reader#read
org.apache.commons.io.IOUtils#copyLarge at line:2537
org.apache.commons.io.IOUtils#copyLarge at line:2516
org.apache.commons.io.IOUtils#copy at line:2493
org.apache.commons.io.IOUtils#copy at line:2441
org.apache.commons.io.IOUtils#toString at line:1084
org.apache.commons.io.IOUtils#toString at line:1064
nz.co.breakpoint.jmeter.vizualizers.sshmon.SSHMonSampler#generateSamples at line:65
kg.apc.jmeter.vizualizers.MonitoringResultsCollector#processConnectors at line:215
kg.apc.jmeter.vizualizers.MonitoringResultsCollector#run at line:122
java.lang.Thread#run

A thread dump shows locked InputStreams, which suggests the Channel is still busy reading command output:

"Thread-430" #422 prio=5 os_prio=0 tid=0x00007f3b50388800 nid=0x504b in Object.wait() [0x00007f3b328aa000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
	at java.lang.Object.wait(Native Method)
	at java.io.PipedInputStream.read(Unknown Source)
	- locked <0x00000000c1e94458> (a com.jcraft.jsch.Channel$MyPipedInputStream)
	at java.io.PipedInputStream.read(Unknown Source)
	- locked <0x00000000c1e94458> (a com.jcraft.jsch.Channel$MyPipedInputStream)
	at sun.nio.cs.StreamDecoder.readBytes(Unknown Source)
	at sun.nio.cs.StreamDecoder.implRead(Unknown Source)
	at sun.nio.cs.StreamDecoder.read(Unknown Source)
	- locked <0x00000000c1e964f8> (a java.io.InputStreamReader)
	at java.io.InputStreamReader.read(Unknown Source)
	at java.io.Reader.read(Unknown Source)
	at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:2537)
	at org.apache.commons.io.IOUtils.copyLarge(IOUtils.java:2516)
	at org.apache.commons.io.IOUtils.copy(IOUtils.java:2493)
	at org.apache.commons.io.IOUtils.copy(IOUtils.java:2441)
	at org.apache.commons.io.IOUtils.toString(IOUtils.java:1084)
	at org.apache.commons.io.IOUtils.toString(IOUtils.java:1064)
	at nz.co.breakpoint.jmeter.vizualizers.sshmon.SSHMonSampler.generateSamples(SSHMonSampler.java:65)
	at kg.apc.jmeter.vizualizers.MonitoringResultsCollector.processConnectors(MonitoringResultsCollector.java:215)
	at kg.apc.jmeter.vizualizers.MonitoringResultsCollector.run(MonitoringResultsCollector.java:122)
	- locked <0x00000000c015b010> (a nz.co.breakpoint.jmeter.vizualizers.sshmon.SSHMonCollector)
	at java.lang.Thread.run(Unknown Source)