Debug-Compiled Server crashes on Database opening

quick background...
have been running AC for WoW 3.3.5 on my server for almost 3 years.(previously TrinityCore)
running older version on an older system.
went to update with latest commits last week and found dependency updates.
reverted back to previous version i was running, which runs fine on main server.
installed on dev server to do some updates and testing config settings using 'Release' build.
client hangs on "Connecting" or "Getting Character List", which i will post about separately. (is not instance reset queries, ~11 threads on "thread_wait")

built server in debug mode to try to track down whats going on.
started in debug mode, crashed on "Opening DatabasePool 'acore_world'.".

bt shows this is in "request = (SQLOperation*)(m_queue->dequeue());" found at 'src/common/Database/DatabaseWorker.cpp:29'.

bt full
#0 0x00007ffff74129ef in ACE_Activation_Queue::dequeue (this=0x7ffff4c7f120, tv=0x0) at ../../ace/Activation_Queue.cpp:89
mb = 0x0
#1 0x00000000020b1874 in DatabaseWorker::svc (this=0x7ffff4cc61e0) at /backups/local/src/azerothcore/src/common/Database/DatabaseWorker.cpp:29
request = 0x0
#2 0x00007ffff74b7ccd in ACE_Task_Base::svc_run (args=0x7ffff4cc61e0) at ../../ace/Task.cpp:271
t = 0x7ffff4cc61e0
status = <optimized out>
thr_mgr_ptr = <optimized out>
#3 0x00007ffff74b9446 in ACE_Thread_Adapter::invoke_i (this=0x7ffff4ca0070) at ../../ace/Thread_Adapter.cpp:161
hook = <optimized out>
func = 0x7ffff74b7c60 <ACE_Task_Base::svc_run(void*)>
arg = 0x7ffff4cc61e0
cancel_flags = 4259842
status = 0x0
#4 0x00007ffff74b94fb in ACE_Thread_Adapter::invoke (this=0x7ffff4ca0070) at ../../ace/Thread_Adapter.cpp:96
exit_hook_instance = <optimized out>
exit_hook_maybe = {instance_ = 0x0}
exit_hook_ptr = 0x7ffff3a69000
exit_hook = @0x7ffff3a69000: {thread_control_ = {tm_ = 0x7ffff4cda140, status_ = 0x0}}
#5 0x00007ffff628f5bd in start_thread () from /lib64/libpthread.so.0
No symbol table info available.
#6 0x00007ffff559e59d in clone () from /lib64/libc.so.6
No symbol table info available.

i am running mageia 5, gcc 4.9.2, cmake 3.0.2, glibc 2.20.27, libACE 6.0.3

i am thinking this is a DB problem, as i have a lot of "MYSQL server has gone away" msgs, and server will hang on shutdown. (cant debug that far, so dont know where or why)

thanks for looking.