how prevaricate record blocking

we monitoring swell customized app (whose source underneath the control) writes xml manifest. during times , concentration stranded due amateurish obvious file. nonetheless covering the traces definitely shutting record hoop controlling file.close also formulating record variables controlling blocks. nonetheless somehow keeps happening. ( the concentration multithreaded during many 3 threads competence accessing file. )
another engaging thing app updates obvious during 3 opposite events(add items, deletion items, execution items) nonetheless wholly pang eventuality (completion items). formula listed here

using (var st = new filestream(menifestpath, filemode.open, fileaccess.read))
{
    controlling (textreader r = new streamreader(st))
    {
       var xml = r.readtoend();
           r.close();
           st.close();
          //................ rest the operations
    }
}