ActiveMQ Hanging Transport and Connectivity

I have a Webservice deployed in Apache ServiceMix that uses Apache Camel to invoke an ActiveMQ-managed route, using code similar to the following:

 context.createProducerTemplate().sendBody("activemq:startComplex", xml);

The call works fine, but after a while the file descriptor limit on my Linux machine falls. Resources are consumed by a number of (several thousand) ActiveMQ threads. In jmx console, I see many threads similar to the following:

Name: ActiveMQ Transport: tcp://localhost/127.0.0.1:61616
State: RUNNABLE
Total blocked: 0  Total waited: 0

Stack trace: 
 java.net.SocketInputStream.socketRead0(Native Method)
java.net.SocketInputStream.read(SocketInputStream.java:129)
org.apache.activemq.transport.tcp.TcpBufferedInputStream.fill(TcpBufferedInputStream.java:5    0)
org.apache.activemq.transport.tcp.TcpTransport$2.fill(TcpTransport.java:589)
org.apache.activemq.transport.tcp.TcpBufferedInputStream.read(TcpBufferedInputStream.java:5    8)
org.apache.activemq.transport.tcp.TcpTransport$2.read(TcpTransport.java:574)
java.io.DataInputStream.readInt(DataInputStream.java:370)
org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275)
org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:222)
org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:214)
org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:197)
java.lang.Thread.run(Thread.java:662)

and

Name: ActiveMQ Transport: tcp:///127.0.0.1:46420
State: RUNNABLE
Total blocked: 0  Total waited: 2

Stack trace: 
 java.net.SocketInputStream.socketRead0(Native Method)
java.net.SocketInputStream.read(SocketInputStream.java:129)
org.apache.activemq.transport.tcp.TcpBufferedInputStream.fill(TcpBufferedInputStream.java:50)
org.apache.activemq.transport.tcp.TcpTransport$2.fill(TcpTransport.java:589)
org.apache.activemq.transport.tcp.TcpBufferedInputStream.read(TcpBufferedInputStream.java:58)
org.apache.activemq.transport.tcp.TcpTransport$2.read(TcpTransport.java:574)
java.io.DataInputStream.readInt(DataInputStream.java:370)
org.apache.activemq.openwire.OpenWireFormat.unmarshal(OpenWireFormat.java:275)
org.apache.activemq.transport.tcp.TcpTransport.readCommand(TcpTransport.java:222)
org.apache.activemq.transport.tcp.TcpTransport.doRun(TcpTransport.java:214)
org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:197)
java.lang.Thread.run(Thread.java:662)

And ideas on how to get rid of hanging threads?