From 8f500c522b5b38b55204031a90977c2c087ffd5c Mon Sep 17 00:00:00 2001 From: Vladislav Vaintroub Date: Thu, 4 Dec 2008 19:41:53 +0100 Subject: 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 client/mysql.cc: sql_protocol_typelib is not exported from libmysqld (does not make sense either) thus excluded from embedded client dbug/dbug.c: revert changes for Bug#38293 include/my_dbug.h: revert changes for Bug#38293 libmysql/libmysql.c: Removed DBUG_POP call, because when called after my_end(), will access THR_key_mysys that is already deleted. The result of pthread_get_specific is not predictable in this case and hence DBUG_POP can crash. libmysqld/examples/CMakeLists.txt: Revert changes for Bug#38293. libmysqld/lib_sql.cc: code to start handle manager is factored out into start_handle_manager() function libmysqld/libmysqld.def: Revert changes for Bug #38293 Remove excessive exports from libmysqld, export what API documents. mysys/my_thr_init.c: Remove windows-DLL-specific workaround for something (old code, no documentation for what specifically). The problem is that even after my_thread_end() is finished, DBUG statement can initiate my_thread_init(). This does not happen anywhere else and should not happen on Windows either. sql/mysql_priv.h: - new functions start_handle_manager() and stop_handle_manager() - move manager_thread_in_use variable to sql_manager.cc and made it static - remove manager_status, as it is unused sql/mysqld.cc: Code to start/stop handle_manager thread is factored out into start_handle_manager() --- sql/sql_manager.cc | 54 +++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 41 insertions(+), 13 deletions(-) (limited to 'sql/sql_manager.cc') diff --git a/sql/sql_manager.cc b/sql/sql_manager.cc index 171ab55145a..b082f65bfb9 100644 --- a/sql/sql_manager.cc +++ b/sql/sql_manager.cc @@ -23,8 +23,9 @@ #include "mysql_priv.h" -ulong volatile manager_status; -bool volatile manager_thread_in_use; + +static bool volatile manager_thread_in_use; +static bool abort_manager; pthread_t manager_thread; pthread_mutex_t LOCK_manager; @@ -63,7 +64,6 @@ bool mysql_manager_submit(void (*action)()) pthread_handler_t handle_manager(void *arg __attribute__((unused))) { int error = 0; - ulong status; struct timespec abstime; bool reset_flush_time = TRUE; struct handler_cb *cb= NULL; @@ -72,7 +72,6 @@ pthread_handler_t handle_manager(void *arg __attribute__((unused))) pthread_detach_this_thread(); manager_thread = pthread_self(); - manager_status = 0; manager_thread_in_use = 1; for (;;) @@ -87,16 +86,14 @@ pthread_handler_t handle_manager(void *arg __attribute__((unused))) set_timespec(abstime, flush_time); reset_flush_time = FALSE; } - while (!manager_status && (!error || error == EINTR) && !abort_loop) + while ((!error || error == EINTR) && !abort_manager) error= pthread_cond_timedwait(&COND_manager, &LOCK_manager, &abstime); } else { - while (!manager_status && (!error || error == EINTR) && !abort_loop) + while ((!error || error == EINTR) && !abort_manager) error= pthread_cond_wait(&COND_manager, &LOCK_manager); } - status = manager_status; - manager_status = 0; if (cb == NULL) { cb= cb_list; @@ -104,7 +101,7 @@ pthread_handler_t handle_manager(void *arg __attribute__((unused))) } pthread_mutex_unlock(&LOCK_manager); - if (abort_loop) + if (abort_manager) break; if (error == ETIMEDOUT || error == ETIME) @@ -121,11 +118,42 @@ pthread_handler_t handle_manager(void *arg __attribute__((unused))) my_free((uchar*)cb, MYF(0)); cb= next; } - - if (status) - DBUG_PRINT("error", ("manager did not handle something: %lx", status)); } manager_thread_in_use = 0; + DBUG_LEAVE; // Can't use DBUG_RETURN after my_thread_end my_thread_end(); - DBUG_RETURN(NULL); + return (NULL); } + + +/* Start handle manager thread */ +void start_handle_manager() +{ + DBUG_ENTER("start_handle_manager"); + abort_manager = false; + if (flush_time && flush_time != ~(ulong) 0L) + { + pthread_t hThread; + if (pthread_create(&hThread,&connection_attrib,handle_manager,0)) + sql_print_warning("Can't create handle_manager thread"); + } + DBUG_VOID_RETURN; +} + + +/* Initiate shutdown of handle manager thread */ +void stop_handle_manager() +{ + DBUG_ENTER("stop_handle_manager"); + abort_manager = true; + pthread_mutex_lock(&LOCK_manager); + if (manager_thread_in_use) + { + DBUG_PRINT("quit", ("initiate shutdown of handle manager thread: 0x%lx", + (ulong)manager_thread)); + pthread_cond_signal(&COND_manager); + } + pthread_mutex_unlock(&LOCK_manager); + DBUG_VOID_RETURN; +} + -- cgit v1.2.1