private void doSerialPooledThread(Runnable command) {
      ConnectionTable.threadWantsSharedResources();
      try {
        command.run();
      } finally {
        ConnectionTable.releaseThreadsSockets();
      }
    }
Holds info about unused thread, a thread is marked unused when the member associated with it
has left distribution system.
geode-core/src/main/java/org/apache/geode/distributed/internal/ClusterOperationExecutors.java