Reuse THD for new user connections

- To ensure that mallocs are marked for the correct THD, even if it's
  allocated in another thread, I added the thread_id to the THD constructor
- Added st_my_thread_var to thr_lock_info_init() to avoid a call to my_thread_var
- Moved things from THD::THD() to THD::init()
- Moved some things to THD::cleanup()
- Added THD::free_connection() and THD::reset_for_reuse()
- Added THD to CONNECT::create_thd()
- Added THD::thread_dbug_id and st_my_thread_var->dbug_id. These are needed
  to ensure that we have a constant thread_id used for debugging with a THD,
  even if it changes thread_id (=connection_id)
- Set variables.pseudo_thread_id in constructor. Removed not needed sets.

1 files changed, 2 insertions, 3 deletions

diff --git a/sql/event_scheduler.cc b/sql/event_scheduler.cc
index 6a8bdabb948..ea0163e3f78 100644
--- a/sql/event_scheduler.cc
+++ b/sql/event_scheduler.cc
@@ -189,7 +189,6 @@ pre_init_event_thread(THD* thd)
   thd->net.read_timeout= slave_net_timeout;
   thd->variables.option_bits|= OPTION_AUTO_IS_NULL;
   thd->client_capabilities|= CLIENT_MULTI_RESULTS;
-  thd->thread_id= thd->variables.pseudo_thread_id= next_thread_id();
 
   /*
     Guarantees that we will see the thread in SHOW PROCESSLIST though its
@@ -396,7 +395,7 @@ Event_scheduler::start(int *err_no)
   if (state > INITIALIZED)
     goto end;
 
-  if (!(new_thd= new THD))
+  if (!(new_thd= new THD(next_thread_id())))
   {
     sql_print_error("Event Scheduler: Cannot initialize the scheduler thread");
     ret= true;
@@ -542,7 +541,7 @@ Event_scheduler::execute_top(Event_queue_element_for_exec *event_name)
   int res= 0;
   DBUG_ENTER("Event_scheduler::execute_top");
 
-  if (!(new_thd= new THD()))
+  if (!(new_thd= new THD(next_thread_id())))
     goto error;
 
   pre_init_event_thread(new_thd);