Bug#38522: 5 seconds delay when closing application using embedded server

                  
The problem here is that embedded server starts handle_thread manager 
thread  on mysql_library_init() does not stop it on mysql_library_end().
At shutdown, my_thread_global_end() waits for thread count to become 0,
but since we did not stop the thread it will give up after 5 seconds.
             
Solution is to move shutdown for handle_manager thread from kill_server()
(mysqld specific) to clean_up() that is used by both embedded and mysqld.
            
This patch also contains some refactorings - to avoid duplicate code,
start_handle_manager() and stop_handle_manager() functions are introduced.
Unused variables are eliminated. handle_manager does not rely on global
variable abort_loop anymore to stop (abort_loop is not set for embedded).
            
Note: Specifically on Windows and when using DBUG version of libmysqld, 
the complete solution requires removing obsolete code my_thread_init() 
from my_thread_var(). This has a side effect that a DBUG statement 
after my_thread_end() can cause thread counter to be incremented, and 
embedded will hang for some seconds. Or worse, my_thread_init() will 
crash if critical sections have been deleted by the global cleanup 
routine that runs in a different thread. 

This patch also fixes and revert prior changes for Bug#38293 
"Libmysqld crash in mysql_library_init if language file missing".

Root cause of the crash observed in Bug#38293  was bug in my_thread_init() 
described above

1 files changed, 1 insertions, 16 deletions

diff --git a/dbug/dbug.c b/dbug/dbug.c
index bbd1abb9598..baf080f5e27 100644
--- a/dbug/dbug.c
+++ b/dbug/dbug.c
@@ -1851,13 +1851,7 @@ static void DBUGOpenFile(CODE_STATE *cs,
       else
       {
         newfile= !EXISTS(name);
-        if (!(fp= fopen(name,
-#if defined(MSDOS) || defined(__WIN__)
-		append ? "a+c" : "wc"
-#else
-                append ? "a+" : "w"
-#endif
-		)))
+        if (!(fp= fopen(name, append ? "a+" : "w")))
         {
           (void) fprintf(stderr, ERR_OPEN, cs->process, name);
           perror("");
@@ -2407,13 +2401,4 @@ int i_am_a_dummy_function() {
        return 0;
 }
 
-#ifdef __WIN__
-char _db_doprnt_;
-char _db_enter_;
-char _db_pargs_;
-char _db_process_;
-char _db_push_;
-char _db_return_;
-#endif /*__WIN__*/
-
 #endif