Observed on file-18 using:

./src/tests/txtest --queues 10 --messages-per-tx 2 --total-messages 2000
--tx-count 1000000 --size 64


#0  std::_Rb_tree<std::string, std::string, std::_Identity<std::string>,
std::less<std::string>, std::allocator<std::string> >::find (this=0x2aaab807f907,
    __k=@0x2aaab8018490)
    at
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/basic_string.h:591
#1  0x00002aaaab986437 in rhm::journal::wmgr::is_txn_synced (this=0xac26700,
    xid=@0x2aaab8018490)
    at
/usr/lib/gcc/x86_64-redhat-linux/4.1.2/../../../../include/c++/4.1.2/bits/stl_set.h:444
#2  0x00002aaaab9636a0 in rhm::journal::jcntl::is_txn_synced (
    this=<value optimized out>, xid=@0x2aaab0203807) at jrnl/jcntl.cpp:391
#3  0x00002aaaab94c777 in rhm::bdbstore::TxnCtxt::sync (this=0x2aaab8018420)
    at TxnCtxt.h:119
#4  0x00002aaaab94caad in rhm::bdbstore::TxnCtxt::completeTXN (
    this=0x2aaab8018420, commit=true) at TxnCtxt.h:89
#5  0x00002aaaab935563 in rhm::bdbstore::BdbMessageStore::commit (
    this=0xa894b30, ctxt=<value optimized out>) at TxnCtxt.h:143
#6  0x00002aaaaab9dfd8 in qpid::broker::MessageStoreModule::commit ()
   from /home/gordon/qpid/cpp/src/.libs/libqpidbroker.so.0
#7  0x00002aaaaabd8743 in qpid::broker::TxBuffer::commitLocal ()
   from /home/gordon/qpid/cpp/src/.libs/libqpidbroker.so.0
#8  0x00002aaaaabb03a0 in qpid::broker::SemanticState::commit ()
   from /home/gordon/qpid/cpp/src/.libs/libqpidbroker.so.0

Suspect due to concurrent access to _pending_txn_set.