Issue with hooks for cassandra

[Amoghrd]

Tried B/R with noobaa enabled for cassandra and the backup partially failed with the following logs

velero backup logs cassandra --insecure-skip-tls-verify=true | grep error time="2020-08-06T16:05:02Z" level=info msg="stderr: error: ThreadPoolExecutor has shut down\n-- StackTrace --\njava.util.concurrent.RejectedExecutionException: ThreadPoolExecutor has shut down\n\tat org.apache.cassandra.concurrent.DebuggableThreadPoolExecutor$1.rejectedExecution(DebuggableThreadPoolExecutor.java:58)\n\tat java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)\n\tat java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)\n\tat org.apache.cassandra.concurrent.DebuggableThreadPoolExecutor.execute(DebuggableThreadPoolExecutor.java:162)\n\tat org.apache.cassandra.db.ColumnFamilyStore.waitForFlushes(ColumnFamilyStore.java:990)\n\tat org.apache.cassandra.db.ColumnFamilyStore.forceFlush(ColumnFamilyStore.java:956)\n\tat org.apache.cassandra.db.ColumnFamilyStore.forceBlockingFlush(ColumnFamilyStore.java:996)\n\tat org.apache.cassandra.service.StorageService.forceKeyspaceFlush(StorageService.java:3434)\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\n\tat java.lang.reflect.Method.invoke(Method.java:498)\n\tat sun.reflect.misc.Trampoline.invoke(MethodUtil.java:72)\n\tat sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\n\tat java.lang.reflect.Method.invoke(Method.java:498)\n\tat sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:276)\n\tat com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:112)\n\tat com.sun.jmx.mbeanserver.StandardMBeanIntrospector.invokeM2(StandardMBeanIntrospector.java:46)\n\tat com.sun.jmx.mbeanserver.MBeanIntrospector.invokeM(MBeanIntrospector.java:237)\n\tat com.sun.jmx.mbeanserver.PerInterface.invoke(PerInterface.java:138)\n\tat com.sun.jmx.mbeanserver.MBeanSupport.invoke(MBeanSupport.java:252)\n\tat com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)\n\tat com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)\n\tat javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1468)\n\tat javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:76)\n\tat javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1309)\n\tat javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1401)\n\tat javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:829)\n\tat sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\n\tat sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)\n\tat sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\n\tat java.lang.reflect.Method.invoke(Method.java:498)\n\tat sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:357)\n\tat sun.rmi.transport.Transport$1.run(Transport.java:200)\n\tat sun.rmi.transport.Transport$1.run(Transport.java:197)\n\tat java.security.AccessController.doPrivileged(Native Method)\n\tat sun.rmi.transport.Transport.serviceCall(Transport.java:196)\n\tat sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)\n\tat sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)\n\tat sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)\n\tat java.security.AccessController.doPrivileged(Native Method)\n\tat sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)\n\tat java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)\n\tat java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)\n\tat java.lang.Thread.run(Thread.java:748)\n\n" backup=oadp-operator/cassandra hookCommand="[/bin/bash -c opt/cassandra/bin/nodetool disablegossip && opt/cassandra/bin/nodetool disablethrift && opt/cassandra/bin/nodetool disablebinary && opt/cassandra/bin/nodetool flush]" hookContainer=cassandra hookName="<from-annotation>" hookOnError=Fail hookPhase=pre hookSource=annotation hookTimeout="{30s}" hookType=exec logSource="pkg/podexec/pod_command_executor.go:172" name=cassandra-0 namespace=cassandra-stateful resource=pods time="2020-08-06T16:05:02Z" level=error msg="Error executing hook" backup=oadp-operator/cassandra error="command terminated with exit code 2" hookPhase=pre hookSource=annotation hookType=exec logSource="pkg/backup/item_hook_handler.go:100" name=cassandra-0 namespace=cassandra-stateful resource=pods time="2020-08-06T16:05:02Z" level=error msg="Error backing up item" backup=oadp-operator/cassandra error="command terminated with exit code 2" logSource="pkg/backup/backup.go:454" name=cassandra-0