Ticket #47349 - DS instance crashes under a high load
Reviewed by: nkinder (Thanks!)
Fix Description: handle_new_connection initializes the connection object,
then calls connection_table_move_connection_on_to_active_list to put it
on the list of active connections, then unlocks the c_mutex, then calls
connection_new_private to allocate c_private. If another thread
interrupts after the conn has been moved to the active list, but before
c_private has been allocated, the new conn will be available via
connection_table_iterate_active_connections where table_iterate_function
will attempt to dereference the NULL c_private.
The fix is to move connection_new_private inside the c_mutex lock, and to
move connection_table_move_connection_on_to_active_list to be the very last
thing before releasing the c_mutex lock. Once the conn is on the active
list it is live and we cannot do anything else to it.
Note: I have still not been able to reproduce the problem in a non-debug
Platforms tested: RHEL6 x86_64
Note: Before patch, server would crash within 5 minutes. After patch, server
has been running for several days in customer environment.
Flag Day: no
Doc impact: no
(cherry picked from commit 05d209432571dc64b242ae47113ae4cbb43607d2)