ConcurrentModificationException thrown from JavaBinCodec

while pressure test by LoadRunner ,There are some ConcurrentModificationException.

Caused by: java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.next(ArrayList.java:837)
at org.apache.solr.common.util.JavaBinCodec.writeArray(JavaBinCodec.java:474)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:250)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.writeSolrInputDocument(JavaBinCodec.java:424)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:250)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.writeSolrInputDocument(JavaBinCodec.java:424)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:274)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:274)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.writeMapEntry(JavaBinCodec.java:509)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:294)

at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:294)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.writeIterator(JavaBinCodec.java:450)
at org.apache.solr.common.util.JavaBinCodec.writeIterator(JavaBinCodec.java:450)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:282)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)

at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.writeNamedList(JavaBinCodec.java:148)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:242)
at org.apache.solr.common.util.JavaBinCodec.writeKnownType(JavaBinCodec.java:242)
at org.apache.solr.common.util.JavaBinCodec.writeVal(JavaBinCodec.java:153)
at org.apache.solr.common.util.JavaBinCodec.marshal(JavaBinCodec.java:96)

at org.apache.solr.common.util.JavaBinCodec.marshal(JavaBinCodec.java:96)
at org.apache.solr.client.solrj.request.JavaBinUpdateRequestCodec.marshal(JavaBinUpdateRequestCodec.java:83)
at org.apache.solr.client.solrj.impl.BinaryRequestWriter.getContentStream(BinaryRequestWriter.java:67)

at org.apache.solr.client.solrj.impl.BinaryRequestWriter.getContentStream(BinaryRequestWriter.java:67)
at org.apache.solr.client.solrj.request.RequestWriter$LazyContentStream.getDelegate(RequestWriter.java:95)
at org.apache.solr.client.solrj.request.RequestWriter$LazyContentStream.getName(RequestWriter.java:105)
at org.apache.solr.client.solrj.request.RequestWriter$LazyContentStream.getName(RequestWriter.java:105)
at org.apache.solr.client.solrj.impl.HttpSolrServer.createMethod(HttpSolrServer.java:370)
at org.apache.solr.client.solrj.impl.HttpSolrServer.createMethod(HttpSolrServer.java:304)
at org.apache.solr.client.solrj.impl.HttpSolrServer.request(HttpSolrServer.java:229)
at org.apache.solr.client.solrj.impl.HttpSolrServer.request(HttpSolrServer.java:225)
at org.apache.solr.client.solrj.impl.LBHttpSolrServer.doRequest(LBHttpSolrServer.java:345)
... 30 more
java.util.ConcurrentModificationException

at org.apache.solr.client.solrj.impl.HttpSolrServer.request(HttpSolrServer.java:229)
at org.apache.solr.client.solrj.impl.HttpSolrServer.request(HttpSolrServer.java:225)
at org.apache.solr.client.solrj.impl.LBHttpSolrServer.doRequest(LBHttpSolrServer.java:345)
... 30 more