ApacheMQ/Camel memory usage

[Geurt Schimmel <GS...@schubergphilis.com>]

Using the Camel File component to consume files from a directory.  Works fine, but once in a week, ActiveMQ is out-of-heap space. Have been experimenting with Xmm and Xms (currently "-Xms384M -Xmx384M"), but higher values just delay the moment where it goes out-of-heap. With jConsole, it's clear heap-space consumption is gradually increasing, and looks it's directly related to the number of files consumed. The files picked up are typically  60-80 bytes, about 300k files/24hr.
The queue is consumed by a Camel exec component on another host (network-of-brokers).

ACTIVEMQ_OPTS="$ACTIVEMQ_OPTS_MEMORY -Dorg.apache.activemq.UseDedicatedTaskRunner=false -Djava.util.logging.config.file=logging.properties"

Software versions:
java version "1.6.0_22" OpenJDK Runtime Environment (IcedTea6 1.10.9) (rhel-1.28.1.10.9.el5_8-x86_64),OpenJDK 64-Bit Server VM (build 20.0-b11, mixed mode)
activemq-camel-5.7-SNAPSHOT

Excerpts from activemq.xml:

<policyEntry queue=">" producerFlowControl="true" memoryLimit="1mb">

   <persistenceAdapter>
      <kahaDB directory="${activemq.base}/data/kahadb"  enableJournalDiskSyncs="false" indexWriteBatchSize="10000" indexCacheSize="1000"/>
    </persistenceAdapter>

<memoryUsage limit="20 mb"/>
<storeUsage limit="1 gb"/>
<tempUsage limit="100 mb"/>


Relevant part of my camel.xml:
    <route>
      <description>file pickup</description>
      <from uri="file:///tmp/drr/?delete=true"/>
      <to uri="activemq:queue:LOCAL.DRR.myhost"/>
    </route>

Please advise - I'm lost (yes, have been reading the faq's, the books, and so on)

Geurt