MySql ODBC driver disconnect very slow on Windows

[Eqbal Zaffar]

We are using mysql connecter 5.3.10 with a third party application on Windows. I am noticing that the ODBC driver SQLDisconnect call is very slow taking sometimes hours to complete. It's spending most of the time in the stack below (multiple threads). If we use SSLMODE=DISABLED in the connection string it's pretty quick. Any idea what could be going on?

00 myodbc5w!yaSSL::input_buffer::get_remaining+0x4 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\extra\yassl\src\buffer.cpp @ 146]
01 myodbc5w!mySTL::for_each<mySTL::list<yaSSL::input_buffer * __ptr64>::iterator,yaSSL::yassl_int_cpp_local1::SumData>+0x29 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\extra\yassl\taocrypt\mystl\algorithm.hpp @ 49]
02 myodbc5w!yaSSL::SSL::bufferedData+0x23 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\extra\yassl\src\yassl_int.cpp @ 1182]
03 myodbc5w!yaSSL::SSL::fillData+0x6d [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\extra\yassl\src\yassl_int.cpp @ 1194]
04 myodbc5w!yaSSL::receiveData+0x7e [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\extra\yassl\src\handshake.cpp @ 1061]
05 myodbc5w!yaSSL_read+0x3c [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\extra\yassl\src\ssl.cpp @ 364]
06 myodbc5w!vio_ssl_read+0x2a [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\vio\viossl.c @ 186]
07 myodbc5w!net_read_raw_loop+0x42 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql\net_serv.cc @ 675]
08 myodbc5w!net_read_packet_header+0x1f [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql\net_serv.cc @ 765]
09 myodbc5w!net_read_packet+0x25 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql\net_serv.cc @ 822]
0a myodbc5w!my_net_read+0x1e [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql\net_serv.cc @ 900]
0b myodbc5w!cli_safe_read_with_ok+0xa4 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql-common\client.c @ 1055]
0c myodbc5w!flush_one_result+0x1d [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql-common\client.c @ 1397]
0d myodbc5w!cli_flush_use_result+0x15 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql-common\client.c @ 1476]
0e myodbc5w!mysql_free_result+0x52 [g:\ade\build\sb_0-26514852-1514435511.83\mysql-5.7.21\sql-common\client.c @ 1626]
0f myodbc5w!free_current_result+0x5a [g:\ade\build\sb_0-26796952-1516358212.03\mysql-connector-odbc-5.3.10-src\driver\my_stmt.c @ 84]
10 myodbc5w!next_result+0xe [g:\ade\build\sb_0-26796952-1516358212.03\mysql-connector-odbc-5.3.10-src\driver\my_stmt.c @ 290]
11 myodbc5w!my_SQLFreeStmtExtended+0xce [g:\ade\build\sb_0-26796952-1516358212.03\mysql-connector-odbc-5.3.10-src\driver\handle.c @ 639]
12 myodbc5w!free_connection_stmts+0x32 [g:\ade\build\sb_0-26796952-1516358212.03\mysql-connector-odbc-5.3.10-src\driver\connect.c @ 941]
13 myodbc5w!SQLDisconnect+0x21 [g:\ade\build\sb_0-26796952-1516358212.03\mysql-connector-odbc-5.3.10-src\driver\connect.c @ 964]
14 ...