Oracle dbxml2.5.16:crash with query execute()

Question

Hi,
I encountered following crash while using DBXML 25.16 with C++ in multi-threaded environment:
#0 0x0fa28704 in DbXml::NsDomElement::NsDomElement(DbXml::NsNode*, DbXml::NsDoc*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#1 0x0fa29928 in DbXml::NsDomElement::getElemParent() () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#2 0x0fa01b50 in DbXml::ElementDescendantAxis::nextNode(DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#3 0x0f9ff6cc in DbXml::DbXmlAxis::next(DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#4 0x0fad68d0 in DbXml::SortingStepIterator::next(DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#5 0x0fac5f98 in DbXml::DecisionPointIterator::next(DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#6 0x0fabcef0 in DbXml::QueryPlanToASTResult::next(DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#7 0x0f31e958 in ResultImpl::nextOrTail(Result&, DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libxqilla.so.5
#8 0x0f31ea48 in ResultImpl::next(DynamicContext*) () from /usr/MotoAgent/thirdparty/lib/libxqilla.so.5
#9 0x0fb49644 in DbXml::LazyDIResults::next(DbXml::XmlValue&) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#10 0x0fb739fc in DbXml::XmlResults::next(DbXml::XmlValue&) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#11 0x0fb43798 in DbXml::ValueResults::init(DbXml::XmlResults&) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#12 0x0fb48ebc in DbXml::ValueResults::ValueResults(DbXml::Results*, DbXml::XmlManager&, DbXml::Transaction*) () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#13 0x0fb4cb48 in DbXml::QueryExpression::execute(DbXml::Transaction*, DbXml::Value*, DbXml::XmlQueryContext&, unsigned int) ()
from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
#14 0x0fb725a4 in DbXml::XmlQueryExpression::execute(DbXml::XmlTransaction&, DbXml::XmlQueryContext&, unsigned int) const () from /usr/MotoAgent/thirdparty/lib/libdbxml-2.5.so
Any patch or workaround to get rid of this issue?

Answer 1

my program crashed without any execption.
I'm running multiple queries from mutiple threads to simualte a scenaio seen in production environment and got his crash 3 times.
I've 9 threads running where 5 threads are reading one XML entry in one document and 1 thread is adding entry into smae document and 2 threads trying to delete the XML entries from the same document. The last thread is reading metadata.
3 crashes with same crash signature seen in reading thread. Below is the code which does perform query:
int performQuery(DbXml::XmlManager *&m_manager_, string & p_queryResult,
const string & p_query,
const map < string, string > *p_pExternalValues)
// Check the input params
if (p_query.empty())
cout << ("Empty XQuery/XQueryUpdate expression");
return MA_GENERAL_ERROR;
u_int32_t my_txn_flags = DB_READ_COMMITTED | DB_TXN_NOSYNC |
DB_TXN_NOWAIT;
if (p_queryResult == C_BDBXML_PERFORM_UPDATE)
my_txn_flags = DB_TXN_SYNC | DB_TXN_NOWAIT;
XmlResults my_results;
int retry_count = 0;
XmlTransaction my_txn;
while (retry_count < C_BDBXML_MAX_RETRIES)
try
// The query context
XmlQueryContext my_qc = m_manager_->createQueryContext();
my_qc.setEvaluationType(XmlQueryContext::Eager);
// Set external variables
if (p_pExternalValues != NULL)
map < string, string >::const_iterator it;
for (it = p_pExternalValues->begin();
it != p_pExternalValues->end(); ++it)
my_qc.setVariableValue(it->first, it->second);
// cout << "external " << it->first << " " << it->second << endl;
// Start transaction
my_txn = m_manager_->createTransaction(my_txn_flags);
// Compile the query
XmlQueryExpression my_query_expr =
m_manager_->prepare(my_txn, p_query, my_qc);
// Perform the query
my_results = my_query_expr.execute(my_txn, my_qc, 0);
// If the method is performing XQuery, parse the results
if (p_queryResult != C_BDBXML_PERFORM_UPDATE)
p_queryResult.clear();
// Parse the results
XmlValue my_value;
while (my_results.next(my_value))
p_queryResult += my_value.asString();
my_txn.commit();
return CNEOMI_SUCCESS;
catch(const XmlException & xe)
bool ret = handleXmlException(xe, my_txn, retry_count);
if(ret != CNEOMI_SUCCESS)
CL_LOG_ERROR_STREAM("Failed to execute the XQuery: " <<
p_query);
if(ret != CNEOMI_SUCCESS)
CL_LOG_ERROR_STREAM("Failed to execute the XQuery: " <<
p_query);
return ret;
CL_LOG_ERROR("Exceeded retry limit. Giving up");
return 2;
And here is my read xquery that crashed:
string docid = string("dbxml:/ma.dbxml/") + (char *)arg;
string query = string("declare variable $self as xs:string external;doc($self)//*//*:") + "clAgentClientOperation";
map<string,string> myexternalValues;
myexternalValues.insert(make_pair<string,string>("self",
docid));
string queryResult;
performQuery(myManager,queryResult,
query,
&myexternalValues);