thread.
Initialization of THD and vio/net initialization happens
in the acceptor thread that accepts the connection. THD and
network initialization involves acquiring locks, memory
allocation of various structures and system calls which are
compute-bound as well as tasks that may block. The acceptor
thread is an event loop that waits for new connection events
from clients. To maximize the number of connections that can
be handled per unit of time, the acceptor thread should
spend as much of its time listening for new connections.
This means thd and vio/net initialization should be
offloaded from the accept event loop and delegated to
worker threads that handle the client connections.
This worklog provides a generic framework which offloads
THD initialization and net/vio initialization to worker
threads for all types of communication channels (shared
memory, named pipes and sockets) that clients connect with
server.
In addition, this worklog refactored the existing
interfaces of the struct scheduler_functions into an object
oriented API, refactored and moved code related to
connection handling and its management into a separate
directory and files that contain implementations of specific
related functionality. This resulted in removal of unnecessary
#defines, modularity, better code clarity and readability in
addition to performance improvements made in the worklog.
As result of changes in this worklog, the follow bugs have
been fixed:
Bug#12951536 - THD INITIALIZATION TOO EXPENSIVE FOR
               ACCEPT() THREAD.
Bug#12951595 - TOO MUCH NETWORK INITIALIZATION DONE
               IN ACCEPT() THREAD.
Bug#12951605 - ACCEPT() SOCKET GETS TOO MUCH OF FCNTL()S.

User Visible Changes:
The system variables "bind_address", "thread_handling",
""thread_cache_size" and status variables "threads_cached",
"Slow_launch_threads" are no longer visible in embedded
server mode (where they have no effect).