OutOfMemoryError: Unable to create new native thread on EAP. Half of available heap occupied by org.hornetq.core.client.impl.ClientSessionFactoryImpl instances

Issue

We received OutOfMemoryError: Unable to create new native thread on EAP 6.0.1

Memory Analyzer Tool (MAT) leak suspect report shows:

264,219 instances of "org.hornetq.core.client.impl.ClientSessionFactoryImpl", loaded by "org.jboss.modules.ModuleClassLoader @ 0xe196b970" occupy 272,770,344 (51.75%) bytes. These instances are referenced from one instance of "java.util.HashMap$Entry[]", loaded by "<system class loader>"

These all seem to be held in memory by a single thread:

Thread-27 (HornetQ-server-HornetQServerImpl::serverUUID=3a863084-f2f8-11e2-a4a4-d1e05e73dcf8-887675906)
  at org.hornetq.utils.UTF8Util$StringUtilBuffer.<init>(II)V (UTF8Util.java:267)
  at org.hornetq.utils.UTF8Util$StringUtilBuffer.<init>()V (UTF8Util.java:261)
  at org.hornetq.utils.UTF8Util.getThreadLocalBuffer()Lorg/hornetq/utils/UTF8Util$StringUtilBuffer; (UTF8Util.java:186)
  at org.hornetq.utils.UTF8Util.saveUTF(Lorg/hornetq/api/core/HornetQBuffer;Ljava/lang/String;)V (UTF8Util.java:45)
  at org.hornetq.core.buffers.impl.ChannelBufferWrapper.writeUTF(Ljava/lang/String;)V (ChannelBufferWrapper.java:197)
  at org.hornetq.core.buffers.impl.ChannelBufferWrapper.writeStringInternal(Ljava/lang/String;)V (ChannelBufferWrapper.java:186)
  at org.hornetq.core.buffers.impl.ChannelBufferWrapper.writeString(Ljava/lang/String;)V (ChannelBufferWrapper.java:166)
  at org.hornetq.core.protocol.core.impl.wireformat.NodeAnnounceMessage.encodeRest(Lorg/hornetq/api/core/HornetQBuffer;)V (NodeAnnounceMessage.java:101)
  at org.hornetq.core.protocol.core.impl.PacketImpl.encode(Lorg/hornetq/spi/core/protocol/RemotingConnection;)Lorg/hornetq/api/core/HornetQBuffer; (PacketImpl.java:242)
  at org.hornetq.core.protocol.core.impl.ChannelImpl.send(Lorg/hornetq/core/protocol/core/Packet;ZZ)V (ChannelImpl.java:183)
  at org.hornetq.core.protocol.core.impl.ChannelImpl.send(Lorg/hornetq/core/protocol/core/Packet;)V (ChannelImpl.java:157)
  at org.hornetq.core.client.impl.ClientSessionFactoryImpl.sendNodeAnnounce(JLjava/lang/String;ZLorg/hornetq/api/core/TransportConfiguration;Lorg/hornetq/api/core/TransportConfiguration;)V (ClientSessionFactoryImpl.java:1342)
  at org.hornetq.core.server.cluster.impl.ClusterConnectionImpl.onConnection(Lorg/hornetq/core/client/impl/ClientSessionFactoryInternal;)V (ClusterConnectionImpl.java:567)
  at org.hornetq.core.client.impl.ClientSessionFactoryImpl.getConnection()Lorg/hornetq/core/protocol/core/CoreRemotingConnection; (ClientSessionFactoryImpl.java:1317)
  at org.hornetq.core.client.impl.ClientSessionFactoryImpl.getConnectionWithRetry(I)V (ClientSessionFactoryImpl.java:994)
  at org.hornetq.core.client.impl.ClientSessionFactoryImpl.connect(IZ)V (ClientSessionFactoryImpl.java:225)
  at org.hornetq.core.client.impl.ServerLocatorImpl.createSessionFactory(Lorg/hornetq/api/core/TransportConfiguration;)Lorg/hornetq/api/core/client/ClientSessionFactory; (ServerLocatorImpl.java:669)
  at org.hornetq.core.client.impl.ServerLocatorImpl.createSessionFactory(Ljava/lang/String;)Lorg/hornetq/api/core/client/ClientSessionFactory; (ServerLocatorImpl.java:625)
  at org.hornetq.core.server.cluster.impl.ClusterConnectionBridge.createSessionFactory()Lorg/hornetq/core/client/impl/ClientSessionFactoryInternal; (ClusterConnectionBridge.java:152)
  at org.hornetq.core.server.cluster.impl.BridgeImpl.connect()V (BridgeImpl.java:792)
  at org.hornetq.core.server.cluster.impl.BridgeImpl$ConnectRunnable.run()V (BridgeImpl.java:1091)
  at org.hornetq.utils.OrderedExecutorFactory$OrderedExecutor$1.run()V (OrderedExecutorFactory.java:100)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(Ljava/util/concurrent/ThreadPoolExecutor$Worker;)V (ThreadPoolExecutor.java:1145)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run()V (ThreadPoolExecutor.java:615)
  at java.lang.Thread.run()V (Thread.java:724)