TMySQLResult copy constructor dumps core

ROOT
1

Hi,

I am using TSQLServer to communication with a MySQL server in a multi-thread program. There is a mutex lock around the calls to MySQL so that only one call is made to the MySQL server at any given time. I have been getting segmentation violations inside the function MySQLServer::Query, right at the time when the function is making a copy of TMySQLResult in the return statement. This has been happening off and on for quite a while and I am note sure quite how to track this one down. Does anyone know how to track this problem down? Thanks.

John

Here goes the problem description.

ROOT version 4.04.02

OS: Linux stargrid01.rcf.bnl.gov 2.4.21-37.ELsmp #1 SMP Wed Sep 7 13:28:55 EDT 2005 i686 i686 i386 GNU/Linux

Listing produced by Totalview: it indicates that it has stop at line 113, which is the line starting with return.

TSQLResult *TMySQLServer::Query(const char *sql)
{
// Execute SQL command. Result object must be deleted by the user.
// Returns a pointer to a TSQLResult object if successful, 0 otherwise.
// The result object must be deleted by the user.

if (!IsConnected()) {
   Error("Query", "not connected");
   return 0;
}

if (mysql_query(fMySQL, sql) < 0) {
   Error("Query", mysql_error(fMySQL));
   return 0;
}

MYSQL_RES *res = mysql_store_result(fMySQL);
return new TMySQLResult(res);

}

Stack Trace
C++ TObject::not-in-charge TObject, FP=11a80338
C++ TSQLResult::not-in-charge TSQLResult, FP=11a80358
C++ TMySQLResult::TMySQLResult, FP=11a80388
C++ TMySQLServer::Query, FP=11a803c8
C++ GCA::FC::selectSource, FP=11a81498
C++ GCA::asyncTagHandler::selectSource, FP=11a81528
C++ GCA::asyncTagHandler::addFiles, FP=11a81728
C++ GCA::imp::fetch, FP=11a81838
C++ GCA::imp::fetchAndLoad, FP=11a81868
ZTv0_n100_N3GCA3imp12fetchAndLoadEPKcS2_S2, FP=11a81888
C++ POA_GC::tableI::_OB_op_fetchAndLoad, FP=11a81928
C++ POA_GC::coordinatorI::_OB_dispatch, FP=11a81948
C++ OBPortableServer::POA_impl::_OB_dispatch, FP=11a819a8
C++ OB::DispatchRequest_impl::invoke, FP=11a819c8
C++ OB::ThreadPoolDispatcher::run, FP=11a81a08
C++ JTCThread::entrance_hook, FP=11a81a68
C++ lsf_thread_adapter, FP=11a81a88
start_thread, FP=11a81b08

2

Hi John,

since you are using totalview which has very good thread debug capabilities did you check that another TMySQLResult is not accessed in another thread at the same time?

Cheers, Fons.