diff options
Diffstat (limited to 'sql/threadpool_generic.cc')
| -rw-r--r-- | sql/threadpool_generic.cc | 702 |
1 files changed, 334 insertions, 368 deletions
diff --git a/sql/threadpool_generic.cc b/sql/threadpool_generic.cc index 3f4997b8238..ed3ba12ee25 100644 --- a/sql/threadpool_generic.cc +++ b/sql/threadpool_generic.cc @@ -13,56 +13,28 @@ along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */ +#if (defined HAVE_POOL_OF_THREADS) && !defined(EMBEDDED_LIBRARY) + +#include "threadpool_generic.h" #include "mariadb.h" #include <violite.h> #include <sql_priv.h> #include <sql_class.h> #include <my_pthread.h> #include <scheduler.h> - -#ifdef HAVE_POOL_OF_THREADS - -#ifdef _WIN32 -/* AIX may define this, too ?*/ -#define HAVE_IOCP -#endif - -#ifdef HAVE_IOCP -#define OPTIONAL_IO_POLL_READ_PARAM this -#else -#define OPTIONAL_IO_POLL_READ_PARAM 0 -#endif - -#ifdef _WIN32 -typedef HANDLE TP_file_handle; -#else -typedef int TP_file_handle; -#define INVALID_HANDLE_VALUE -1 -#endif - - #include <sql_connect.h> #include <mysqld.h> #include <debug_sync.h> #include <time.h> #include <sql_plist.h> #include <threadpool.h> -#include <time.h> -#ifdef __linux__ -#include <sys/epoll.h> -typedef struct epoll_event native_event; -#elif defined(HAVE_KQUEUE) -#include <sys/event.h> -typedef struct kevent native_event; -#elif defined (__sun) -#include <port.h> -typedef port_event_t native_event; -#elif defined (HAVE_IOCP) -typedef OVERLAPPED_ENTRY native_event; -#else -#error threadpool is not available on this platform -#endif +#include <algorithm> +#ifdef HAVE_IOCP +#define OPTIONAL_IO_POLL_READ_PARAM this +#else +#define OPTIONAL_IO_POLL_READ_PARAM 0 +#endif static void io_poll_close(TP_file_handle fd) { @@ -73,7 +45,6 @@ static void io_poll_close(TP_file_handle fd) #endif } - /** Maximum number of native events a listener can read in one go */ #define MAX_EVENTS 1024 @@ -112,93 +83,14 @@ static PSI_thread_info thread_list[] = {&key_timer_thread, "timer_thread", PSI_FLAG_GLOBAL} }; -/* Macro to simplify performance schema registration */ +/* Macro to simplify performance schema registration */ #define PSI_register(X) \ if(PSI_server) PSI_server->register_ ## X("threadpool", X ## _list, array_elements(X ## _list)) #else #define PSI_register(X) /* no-op */ #endif - -struct thread_group_t; - -/* Per-thread structure for workers */ -struct worker_thread_t -{ - ulonglong event_count; /* number of request handled by this thread */ - thread_group_t* thread_group; - worker_thread_t *next_in_list; - worker_thread_t **prev_in_list; - - mysql_cond_t cond; - bool woken; -}; - -typedef I_P_List<worker_thread_t, I_P_List_adapter<worker_thread_t, - &worker_thread_t::next_in_list, - &worker_thread_t::prev_in_list> - > -worker_list_t; - -struct TP_connection_generic:public TP_connection -{ - TP_connection_generic(CONNECT *c); - ~TP_connection_generic(); - - virtual int init(){ return 0; }; - virtual void set_io_timeout(int sec); - virtual int start_io(); - virtual void wait_begin(int type); - virtual void wait_end(); - - thread_group_t *thread_group; - TP_connection_generic *next_in_queue; - TP_connection_generic **prev_in_queue; - ulonglong abs_wait_timeout; - ulonglong dequeue_time; - TP_file_handle fd; - bool bound_to_poll_descriptor; - int waiting; -#ifdef HAVE_IOCP - OVERLAPPED overlapped; -#endif -#ifdef _WIN32 - enum_vio_type vio_type; -#endif -}; - - -typedef I_P_List<TP_connection_generic, - I_P_List_adapter<TP_connection_generic, - &TP_connection_generic::next_in_queue, - &TP_connection_generic::prev_in_queue>, - I_P_List_null_counter, - I_P_List_fast_push_back<TP_connection_generic> > -connection_queue_t; - -const int NQUEUES=2; /* We have high and low priority queues*/ - -struct MY_ALIGNED(CPU_LEVEL1_DCACHE_LINESIZE) thread_group_t -{ - mysql_mutex_t mutex; - connection_queue_t queues[NQUEUES]; - worker_list_t waiting_threads; - worker_thread_t *listener; - pthread_attr_t *pthread_attr; - TP_file_handle pollfd; - int thread_count; - int active_thread_count; - int connection_count; - /* Stats for the deadlock detection timer routine.*/ - int io_event_count; - int queue_event_count; - ulonglong last_thread_creation_time; - int shutdown_pipe[2]; - bool shutdown; - bool stalled; -}; - -static thread_group_t *all_groups; +thread_group_t *all_groups; static uint group_count; static Atomic_counter<uint32_t> shutdown_group_count; @@ -224,9 +116,9 @@ static pool_timer_t pool_timer; static void queue_put(thread_group_t *thread_group, TP_connection_generic *connection); static void queue_put(thread_group_t *thread_group, native_event *ev, int cnt); -static int wake_thread(thread_group_t *thread_group); -static int wake_or_create_thread(thread_group_t *thread_group); -static int create_worker(thread_group_t *thread_group); +static int wake_thread(thread_group_t *thread_group,bool due_to_stall); +static int wake_or_create_thread(thread_group_t *thread_group, bool due_to_stall=false); +static int create_worker(thread_group_t *thread_group, bool due_to_stall); static void *worker_main(void *param); static void check_stall(thread_group_t *thread_group); static void set_next_timeout_check(ulonglong abstime); @@ -234,48 +126,47 @@ static void print_pool_blocked_message(bool); /** Asynchronous network IO. - - We use native edge-triggered network IO multiplexing facility. + + We use native edge-triggered network IO multiplexing facility. This maps to different APIs on different Unixes. - + Supported are currently Linux with epoll, Solaris with event ports, OSX and BSD with kevent, Windows with IOCP. All those API's are used with one-shot flags - (the event is signalled once client has written something into the socket, + (the event is signalled once client has written something into the socket, then socket is removed from the "poll-set" until the command is finished, and we need to re-arm/re-register socket) - + No implementation for poll/select is currently provided. - - The API closely resembles all of the above mentioned platform APIs - and consists of following functions. - + + The API closely resembles all of the above mentioned platform APIs + and consists of following functions. + - io_poll_create() - Creates an io_poll descriptor + Creates an io_poll descriptor On Linux: epoll_create() - + - io_poll_associate_fd(int poll_fd, TP_file_handle fd, void *data, void *opt) - Associate file descriptor with io poll descriptor + Associate file descriptor with io poll descriptor On Linux : epoll_ctl(..EPOLL_CTL_ADD)) - + - io_poll_disassociate_fd(TP_file_handle pollfd, TP_file_handle fd) - Associate file descriptor with io poll descriptor + Associate file descriptor with io poll descriptor On Linux: epoll_ctl(..EPOLL_CTL_DEL) - - + + - io_poll_start_read(int poll_fd,int fd, void *data, void *opt) - The same as io_poll_associate_fd(), but cannot be used before + The same as io_poll_associate_fd(), but cannot be used before io_poll_associate_fd() was called. On Linux : epoll_ctl(..EPOLL_CTL_MOD) - - - io_poll_wait (TP_file_handle pollfd, native_event *native_events, int maxevents, + + - io_poll_wait (TP_file_handle pollfd, native_event *native_events, int maxevents, int timeout_ms) - - wait until one or more descriptors added with io_poll_associate_fd() - or io_poll_start_read() becomes readable. Data associated with - descriptors can be retrieved from native_events array, using + + wait until one or more descriptors added with io_poll_associate_fd() + or io_poll_start_read() becomes readable. Data associated with + descriptors can be retrieved from native_events array, using native_event_get_userdata() function. - On Linux: epoll_wait() */ @@ -307,7 +198,7 @@ int io_poll_start_read(TP_file_handle pollfd, TP_file_handle fd, void *data, voi ev.data.u64= 0; /* Keep valgrind happy */ ev.data.ptr= data; ev.events= EPOLLIN|EPOLLET|EPOLLERR|EPOLLRDHUP|EPOLLONESHOT; - return epoll_ctl(pollfd, EPOLL_CTL_MOD, fd, &ev); + return epoll_ctl(pollfd, EPOLL_CTL_MOD, fd, &ev); } int io_poll_disassociate_fd(TP_file_handle pollfd, TP_file_handle fd) @@ -322,11 +213,11 @@ int io_poll_disassociate_fd(TP_file_handle pollfd, TP_file_handle fd) NOTE - in case of EINTR, it restarts with original timeout. Since we use either infinite or 0 timeouts, this is not critical */ -int io_poll_wait(TP_file_handle pollfd, native_event *native_events, int maxevents, +int io_poll_wait(TP_file_handle pollfd, native_event *native_events, int maxevents, int timeout_ms) { int ret; - do + do { ret = epoll_wait(pollfd, native_events, maxevents, timeout_ms); } @@ -342,15 +233,20 @@ static void *native_event_get_userdata(native_event *event) #elif defined(HAVE_KQUEUE) -/* - NetBSD is incompatible with other BSDs , last parameter in EV_SET macro - (udata, user data) needs to be intptr_t, whereas it needs to be void* - everywhere else. +/* + NetBSD prior to 9.99.17 is incompatible with other BSDs, last parameter + in EV_SET macro (udata, user data) needs to be intptr_t, whereas it needs + to be void* everywhere else. */ #ifdef __NetBSD__ +#include <sys/param.h> +# if !__NetBSD_Prereq__(9,99,17) #define MY_EV_SET(a, b, c, d, e, f, g) EV_SET(a, b, c, d, e, f, (intptr_t)g) -#else +# endif +#endif + +#ifndef MY_EV_SET #define MY_EV_SET(a, b, c, d, e, f, g) EV_SET(a, b, c, d, e, f, g) #endif @@ -363,18 +259,18 @@ TP_file_handle io_poll_create() int io_poll_start_read(TP_file_handle pollfd, TP_file_handle fd, void *data,void *) { struct kevent ke; - MY_EV_SET(&ke, fd, EVFILT_READ, EV_ADD|EV_ONESHOT, + MY_EV_SET(&ke, fd, EVFILT_READ, EV_ADD|EV_ONESHOT, 0, 0, data); - return kevent(pollfd, &ke, 1, 0, 0, 0); + return kevent(pollfd, &ke, 1, 0, 0, 0); } int io_poll_associate_fd(TP_file_handle pollfd, TP_file_handle fd, void *data,void *) { struct kevent ke; - MY_EV_SET(&ke, fd, EVFILT_READ, EV_ADD|EV_ONESHOT, + MY_EV_SET(&ke, fd, EVFILT_READ, EV_ADD|EV_ONESHOT, 0, 0, data); - return io_poll_start_read(pollfd,fd, data, 0); + return io_poll_start_read(pollfd,fd, data, 0); } @@ -397,7 +293,7 @@ int io_poll_wait(TP_file_handle pollfd, struct kevent *events, int maxevents, in } do { - ret= kevent(pollfd, 0, 0, events, maxevents, + ret= kevent(pollfd, 0, 0, events, maxevents, (timeout_ms >= 0)?&ts:NULL); } while (ret == -1 && errno == EINTR); @@ -496,15 +392,44 @@ int io_poll_start_read(TP_file_handle pollfd, TP_file_handle fd, void *, void *o static int io_poll_associate_fd(TP_file_handle pollfd, TP_file_handle fd, void *data, void *opt) { HANDLE h= CreateIoCompletionPort(fd, pollfd, (ULONG_PTR)data, 0); - if (!h) + if (!h) return -1; - return io_poll_start_read(pollfd,fd, 0, opt); + return io_poll_start_read(pollfd,fd, 0, opt); } +typedef LONG NTSTATUS; + +typedef struct _IO_STATUS_BLOCK { + union { + NTSTATUS Status; + PVOID Pointer; + }; + ULONG_PTR Information; +} IO_STATUS_BLOCK, * PIO_STATUS_BLOCK; + +struct FILE_COMPLETION_INFORMATION { + HANDLE Port; + PVOID Key; +}; + +enum FILE_INFORMATION_CLASS { + FileReplaceCompletionInformation = 0x3D +}; + + +typedef NTSTATUS(WINAPI* pNtSetInformationFile)(HANDLE, PIO_STATUS_BLOCK, PVOID, ULONG, FILE_INFORMATION_CLASS); + int io_poll_disassociate_fd(TP_file_handle pollfd, TP_file_handle fd) { - /* Not possible to unbind/rebind file descriptor in IOCP. */ + static pNtSetInformationFile my_NtSetInformationFile = (pNtSetInformationFile) + GetProcAddress(GetModuleHandle("ntdll"), "NtSetInformationFile"); + if (!my_NtSetInformationFile) + return -1; /* unexpected, we only support Windows 8.1+*/ + IO_STATUS_BLOCK iosb{}; + FILE_COMPLETION_INFORMATION fci{}; + if (my_NtSetInformationFile(fd,&iosb,&fci,sizeof(fci),FileReplaceCompletionInformation)) + return -1; return 0; } @@ -512,9 +437,9 @@ int io_poll_disassociate_fd(TP_file_handle pollfd, TP_file_handle fd) int io_poll_wait(TP_file_handle pollfd, native_event *events, int maxevents, int timeout_ms) { ULONG n; - BOOL ok = GetQueuedCompletionStatusEx(pollfd, events, + BOOL ok = GetQueuedCompletionStatusEx(pollfd, events, maxevents, &n, timeout_ms, FALSE); - + return ok ? (int)n : -1; } @@ -539,7 +464,17 @@ static TP_connection_generic *queue_get(thread_group_t *thread_group) if (c) DBUG_RETURN(c); } - DBUG_RETURN(0); + DBUG_RETURN(0); +} + +static TP_connection_generic* queue_get(thread_group_t* group, operation_origin origin) +{ + auto ret = queue_get(group); + if (ret) + { + TP_INCREMENT_GROUP_COUNTER(group, dequeues[(int)origin]); + } + return ret; } static bool is_queue_empty(thread_group_t *thread_group) @@ -563,17 +498,17 @@ static void queue_init(thread_group_t *thread_group) static void queue_put(thread_group_t *thread_group, native_event *ev, int cnt) { - ulonglong now= pool_timer.current_microtime; + ulonglong now= threadpool_exact_stats?microsecond_interval_timer():pool_timer.current_microtime; for(int i=0; i < cnt; i++) { TP_connection_generic *c = (TP_connection_generic *)native_event_get_userdata(&ev[i]); - c->dequeue_time= now; + c->enqueue_time= now; thread_group->queues[c->priority].push_back(c); } } -/* - Handle wait timeout : +/* + Handle wait timeout : Find connections that have been idle for too long and kill them. Also, recalculate time when next timeout check should run. */ @@ -609,16 +544,16 @@ static my_bool timeout_check(THD *thd, pool_timer_t *timer) } -/* - Timer thread. - +/* + Timer thread. + Periodically, check if one of the thread groups is stalled. Stalls happen if - events are not being dequeued from the queue, or from the network, Primary - reason for stall can be a lengthy executing non-blocking request. It could - also happen that thread is waiting but wait_begin/wait_end is forgotten by - storage engine. Timer thread will create a new thread in group in case of + events are not being dequeued from the queue, or from the network, Primary + reason for stall can be a lengthy executing non-blocking request. It could + also happen that thread is waiting but wait_begin/wait_end is forgotten by + storage engine. Timer thread will create a new thread in group in case of a stall. - + Besides checking for stalls, timer thread is also responsible for terminating clients that have been idle for longer than wait_timeout seconds. @@ -653,14 +588,14 @@ static void* timer_thread(void *param) if (err == ETIMEDOUT) { timer->current_microtime= microsecond_interval_timer(); - + /* Check stalls in thread groups */ for (i= 0; i < threadpool_max_size; i++) { if(all_groups[i].connection_count) check_stall(&all_groups[i]); } - + /* Check if any client exceeded wait_timeout */ if (timer->next_timeout_check.load(std::memory_order_relaxed) <= timer->current_microtime) @@ -693,7 +628,7 @@ void check_stall(thread_group_t *thread_group) for (;;) { c= thread_group->queues[TP_PRIORITY_LOW].front(); - if (c && pool_timer.current_microtime - c->dequeue_time > 1000ULL * threadpool_prio_kickup_timer) + if (c && pool_timer.current_microtime - c->enqueue_time > 1000ULL * threadpool_prio_kickup_timer) { thread_group->queues[TP_PRIORITY_LOW].remove(c); thread_group->queues[TP_PRIORITY_HIGH].push_back(c); @@ -703,27 +638,27 @@ void check_stall(thread_group_t *thread_group) } /* - Check if listener is present. If not, check whether any IO - events were dequeued since last time. If not, this means - listener is either in tight loop or thd_wait_begin() + Check if listener is present. If not, check whether any IO + events were dequeued since last time. If not, this means + listener is either in tight loop or thd_wait_begin() was forgotten. Create a new worker(it will make itself listener). */ if (!thread_group->listener && !thread_group->io_event_count) { - wake_or_create_thread(thread_group); + wake_or_create_thread(thread_group, true); mysql_mutex_unlock(&thread_group->mutex); return; } - + /* Reset io event count */ thread_group->io_event_count= 0; - /* + /* Check whether requests from the workqueue are being dequeued. The stall detection and resolution works as follows: - 1. There is a counter thread_group->queue_event_count for the number of + 1. There is a counter thread_group->queue_event_count for the number of events removed from the queue. Timer resets the counter to 0 on each run. 2. Timer determines stall if this counter remains 0 since last check and the queue is not empty. @@ -734,25 +669,26 @@ void check_stall(thread_group_t *thread_group) Q : Will this handling lead to an unbound growth of threads, if queue stalls permanently? A : No. If queue stalls permanently, it is an indication for many very long - simultaneous queries. The maximum number of simultanoues queries is + simultaneous queries. The maximum number of simultanoues queries is max_connections, further we have threadpool_max_threads limit, upon which no - worker threads are created. So in case there is a flood of very long + worker threads are created. So in case there is a flood of very long queries, threadpool would slowly approach thread-per-connection behavior. NOTE: If long queries never wait, creation of the new threads is done by timer, - so it is slower than in real thread-per-connection. However if long queries + so it is slower than in real thread-per-connection. However if long queries do wait and indicate that via thd_wait_begin/end callbacks, thread creation will be faster. */ if (!is_queue_empty(thread_group) && !thread_group->queue_event_count) { thread_group->stalled= true; - wake_or_create_thread(thread_group); + TP_INCREMENT_GROUP_COUNTER(thread_group,stalls); + wake_or_create_thread(thread_group,true); } - + /* Reset queue event count */ thread_group->queue_event_count= 0; - + mysql_mutex_unlock(&thread_group->mutex); } @@ -784,10 +720,10 @@ static void stop_timer(pool_timer_t *timer) /** Poll for socket events and distribute them to worker threads In many case current thread will handle single event itself. - + @return a ready connection, or NULL on shutdown */ -static TP_connection_generic * listener(worker_thread_t *current_thread, +static TP_connection_generic * listener(worker_thread_t *current_thread, thread_group_t *thread_group) { DBUG_ENTER("listener"); @@ -797,12 +733,12 @@ static TP_connection_generic * listener(worker_thread_t *current_thread, { native_event ev[MAX_EVENTS]; int cnt; - + if (thread_group->shutdown) break; - + cnt = io_poll_wait(thread_group->pollfd, ev, MAX_EVENTS, -1); - + TP_INCREMENT_GROUP_COUNTER(thread_group, polls[(int)operation_origin::LISTENER]); if (cnt <=0) { DBUG_ASSERT(thread_group->shutdown); @@ -816,59 +752,58 @@ static TP_connection_generic * listener(worker_thread_t *current_thread, mysql_mutex_unlock(&thread_group->mutex); break; } - - thread_group->io_event_count += cnt; - - /* + + thread_group->io_event_count += cnt; + + /* We got some network events and need to make decisions : whether listener hould handle events and whether or not any wake worker threads so they can handle events. - - Q1 : Should listener handle an event itself, or put all events into + + Q1 : Should listener handle an event itself, or put all events into queue and let workers handle the events? - + Solution : - Generally, listener that handles events itself is preferable. We do not - want listener thread to change its state from waiting to running too + Generally, listener that handles events itself is preferable. We do not + want listener thread to change its state from waiting to running too often, Since listener has just woken from poll, it better uses its time slice and does some work. Besides, not handling events means they go to the queue, and often to wake another worker must wake up to handle the event. This is not good, as we want to avoid wakeups. - + The downside of listener that also handles queries is that we can - potentially leave thread group for long time not picking the new + potentially leave thread group for long time not picking the new network events. It is not a major problem, because this stall will be detected sooner or later by the timer thread. Still, relying on timer is not always good, because it may "tick" too slow (large timer_interval) - + We use following strategy to solve this problem - if queue was not empty - we suspect flood of network events and listener stays, Otherwise, it + we suspect flood of network events and listener stays, Otherwise, it handles a query. - - + Q2: If queue is not empty, how many workers to wake? - + Solution: - We generally try to keep one thread per group active (threads handling - queries are considered active, unless they stuck in inside some "wait") - Thus, we will wake only one worker, and only if there is not active - threads currently,and listener is not going to handle a query. When we - don't wake, we hope that currently active threads will finish fast and + We generally try to keep one thread per group active (threads handling + queries are considered active, unless they stuck in inside some "wait") + Thus, we will wake only one worker, and only if there is not active + threads currently,and listener is not going to handle a query. When we + don't wake, we hope that currently active threads will finish fast and handle the queue. If this does not happen, timer thread will detect stall and wake a worker. - - NOTE: Currently nothing is done to detect or prevent long queuing times. - A solution for the future would be to give up "one active thread per - group" principle, if events stay in the queue for too long, and just wake + + NOTE: Currently nothing is done to detect or prevent long queuing times. + A solution for the future would be to give up "one active thread per + group" principle, if events stay in the queue for too long, and just wake more workers. */ - - bool listener_picks_event=is_queue_empty(thread_group); + + bool listener_picks_event=is_queue_empty(thread_group) && !threadpool_dedicated_listener; queue_put(thread_group, ev, cnt); if (listener_picks_event) { /* Handle the first event. */ - retval= queue_get(thread_group); + retval= queue_get(thread_group, operation_origin::LISTENER); mysql_mutex_unlock(&thread_group->mutex); break; } @@ -876,25 +811,25 @@ static TP_connection_generic * listener(worker_thread_t *current_thread, if(thread_group->active_thread_count==0) { /* We added some work items to queue, now wake a worker. */ - if(wake_thread(thread_group)) + if(wake_thread(thread_group, false)) { - /* + /* Wake failed, hence groups has no idle threads. Now check if there are any threads in the group except listener. - */ + */ if(thread_group->thread_count == 1) { /* Currently there is no worker thread in the group, as indicated by - thread_count == 1 (this means listener is the only one thread in + thread_count == 1 (this means listener is the only one thread in the group). The queue is not empty, and listener is not going to handle events. In order to drain the queue, we create a worker here. - Alternatively, we could just rely on timer to detect stall, and + Alternatively, we could just rely on timer to detect stall, and create thread, but waiting for timer would be an inefficient and pointless delay. */ - create_worker(thread_group); + create_worker(thread_group, false); } } } @@ -905,7 +840,7 @@ static TP_connection_generic * listener(worker_thread_t *current_thread, } /** - Adjust thread counters in group or global + Adjust thread counters in group or global whenever thread is created or is about to exit @param thread_group @@ -923,20 +858,20 @@ static void add_thread_count(thread_group_t *thread_group, int32 count) /** - Creates a new worker thread. - thread_mutex must be held when calling this function + Creates a new worker thread. + thread_mutex must be held when calling this function NOTE: in rare cases, the number of threads can exceed threadpool_max_threads, because we need at least 2 threads per group to prevent deadlocks (one listener + one worker) */ -static int create_worker(thread_group_t *thread_group) +static int create_worker(thread_group_t *thread_group, bool due_to_stall) { pthread_t thread_id; bool max_threads_reached= false; int err; - + DBUG_ENTER("create_worker"); if (tp_stats.num_worker_threads >= threadpool_max_threads && thread_group->thread_count >= 2) @@ -946,14 +881,18 @@ static int create_worker(thread_group_t *thread_group) goto end; } - - err= mysql_thread_create(key_worker_thread, &thread_id, + err= mysql_thread_create(key_worker_thread, &thread_id, thread_group->pthread_attr, worker_main, thread_group); if (!err) { thread_group->last_thread_creation_time=microsecond_interval_timer(); statistic_increment(thread_created,&LOCK_status); add_thread_count(thread_group, 1); + TP_INCREMENT_GROUP_COUNTER(thread_group,thread_creations); + if(due_to_stall) + { + TP_INCREMENT_GROUP_COUNTER(thread_group, thread_creations_due_to_stall); + } } else { @@ -965,82 +904,86 @@ end: print_pool_blocked_message(max_threads_reached); else pool_block_start= 0; /* Reset pool blocked timer, if it was set */ - + DBUG_RETURN(err); } /** Calculate microseconds throttling delay for thread creation. - + The value depends on how many threads are already in the group: small number of threads means no delay, the more threads the larger the delay. - + The actual values were not calculated using any scientific methods. They just look right, and behave well in practice. - - TODO: Should throttling depend on thread_pool_stall_limit? */ + +#define THROTTLING_FACTOR (threadpool_stall_limit/std::max(DEFAULT_THREADPOOL_STALL_LIMIT,threadpool_stall_limit)) + static ulonglong microsecond_throttling_interval(thread_group_t *thread_group) { int count= thread_group->thread_count; - - if (count < 4) + + if (count < 1+ (int)threadpool_oversubscribe) return 0; - + if (count < 8) - return 50*1000; - + return 50*1000*THROTTLING_FACTOR; + if(count < 16) - return 100*1000; - - return 200*1000; + return 100*1000*THROTTLING_FACTOR; + + return 200*100*THROTTLING_FACTOR; } /** - Wakes a worker thread, or creates a new one. - + Wakes a worker thread, or creates a new one. + Worker creation is throttled, so we avoid too many threads to be created during the short time. */ -static int wake_or_create_thread(thread_group_t *thread_group) +static int wake_or_create_thread(thread_group_t *thread_group, bool due_to_stall) { DBUG_ENTER("wake_or_create_thread"); - + if (thread_group->shutdown) DBUG_RETURN(0); - if (wake_thread(thread_group) == 0) + if (wake_thread(thread_group, due_to_stall) == 0) + { DBUG_RETURN(0); + } if (thread_group->thread_count > thread_group->connection_count) DBUG_RETURN(-1); - + if (thread_group->active_thread_count == 0) { /* - We're better off creating a new thread here with no delay, either there - are no workers at all, or they all are all blocking and there was no - idle thread to wakeup. Smells like a potential deadlock or very slowly + We're better off creating a new thread here with no delay, either there + are no workers at all, or they all are all blocking and there was no + idle thread to wakeup. Smells like a potential deadlock or very slowly executing requests, e.g sleeps or user locks. */ - DBUG_RETURN(create_worker(thread_group)); + DBUG_RETURN(create_worker(thread_group, due_to_stall)); } ulonglong now = microsecond_interval_timer(); ulonglong time_since_last_thread_created = (now - thread_group->last_thread_creation_time); - - /* Throttle thread creation. */ + + /* Throttle thread creation. */ if (time_since_last_thread_created > microsecond_throttling_interval(thread_group)) { - DBUG_RETURN(create_worker(thread_group)); + DBUG_RETURN(create_worker(thread_group, due_to_stall)); } - + + TP_INCREMENT_GROUP_COUNTER(thread_group,throttles); DBUG_RETURN(-1); } @@ -1089,7 +1032,7 @@ void thread_group_destroy(thread_group_t *thread_group) Wake sleeping thread from waiting list */ -static int wake_thread(thread_group_t *thread_group) +static int wake_thread(thread_group_t *thread_group,bool due_to_stall) { DBUG_ENTER("wake_thread"); worker_thread_t *thread = thread_group->waiting_threads.front(); @@ -1098,12 +1041,17 @@ static int wake_thread(thread_group_t *thread_group) thread->woken= true; thread_group->waiting_threads.remove(thread); mysql_cond_signal(&thread->cond); + TP_INCREMENT_GROUP_COUNTER(thread_group, wakes); + if (due_to_stall) + { + TP_INCREMENT_GROUP_COUNTER(thread_group, wakes_due_to_stall); + } DBUG_RETURN(0); } DBUG_RETURN(1); /* no thread in waiter list => missed wakeup */ } -/* +/* Wake listener thread (during shutdown) Self-pipe trick is used in most cases,except IOCP. */ @@ -1132,8 +1080,8 @@ static int wake_listener(thread_group_t *thread_group) /** Initiate shutdown for thread group. - The shutdown is asynchronous, we only care to wake all threads in here, so - they can finish. We do not wait here until threads terminate. Final cleanup + The shutdown is asynchronous, we only care to wake all threads in here, so + they can finish. We do not wait here until threads terminate. Final cleanup of the group (thread_group_destroy) will be done by the last exiting threads. */ @@ -1142,32 +1090,32 @@ static void thread_group_close(thread_group_t *thread_group) DBUG_ENTER("thread_group_close"); mysql_mutex_lock(&thread_group->mutex); - if (thread_group->thread_count == 0) + if (thread_group->thread_count == 0) { mysql_mutex_unlock(&thread_group->mutex); thread_group_destroy(thread_group); DBUG_VOID_RETURN; } - thread_group->shutdown= true; + thread_group->shutdown= true; thread_group->listener= NULL; wake_listener(thread_group); /* Wake all workers. */ - while(wake_thread(thread_group) == 0) - { + while(wake_thread(thread_group, false) == 0) + { } - + mysql_mutex_unlock(&thread_group->mutex); DBUG_VOID_RETURN; } -/* +/* Add work to the queue. Maybe wake a worker if they all sleep. - + Currently, this function is only used when new connections need to perform login (this is done in worker threads). @@ -1177,7 +1125,7 @@ static void queue_put(thread_group_t *thread_group, TP_connection_generic *conne { DBUG_ENTER("queue_put"); - connection->dequeue_time= pool_timer.current_microtime; + connection->enqueue_time= threadpool_exact_stats?microsecond_interval_timer():pool_timer.current_microtime; thread_group->queues[connection->priority].push_back(connection); if (thread_group->active_thread_count == 0) @@ -1187,39 +1135,39 @@ static void queue_put(thread_group_t *thread_group, TP_connection_generic *conne } -/* - Prevent too many threads executing at the same time,if the workload is +/* + Prevent too many threads executing at the same time,if the workload is not CPU bound. */ static bool too_many_threads(thread_group_t *thread_group) { - return (thread_group->active_thread_count >= 1+(int)threadpool_oversubscribe + return (thread_group->active_thread_count >= 1+(int)threadpool_oversubscribe && !thread_group->stalled); } /** Retrieve a connection with pending event. - - Pending event in our case means that there is either a pending login request + + Pending event in our case means that there is either a pending login request (if connection is not yet logged in), or there are unread bytes on the socket. - If there are no pending events currently, thread will wait. + If there are no pending events currently, thread will wait. If timeout specified in abstime parameter passes, the function returns NULL. - + @param current_thread - current worker thread @param thread_group - current thread group @param abstime - absolute wait timeout - + @return - connection with pending event. + connection with pending event. NULL is returned if timeout has expired,or on shutdown. */ -TP_connection_generic *get_event(worker_thread_t *current_thread, +TP_connection_generic *get_event(worker_thread_t *current_thread, thread_group_t *thread_group, struct timespec *abstime) -{ +{ DBUG_ENTER("get_event"); TP_connection_generic *connection = NULL; @@ -1227,19 +1175,21 @@ TP_connection_generic *get_event(worker_thread_t *current_thread, mysql_mutex_lock(&thread_group->mutex); DBUG_ASSERT(thread_group->active_thread_count >= 0); - for(;;) + for(;;) { int err=0; - bool oversubscribed = too_many_threads(thread_group); + bool oversubscribed = too_many_threads(thread_group); if (thread_group->shutdown) break; /* Check if queue is not empty */ if (!oversubscribed) { - connection = queue_get(thread_group); + connection = queue_get(thread_group, operation_origin::WORKER); if(connection) + { break; + } } /* If there is currently no listener in the group, become one. */ @@ -1257,41 +1207,41 @@ TP_connection_generic *get_event(worker_thread_t *current_thread, thread_group->listener= NULL; break; } - - /* - Last thing we try before going to sleep is to + + /* + Last thing we try before going to sleep is to non-blocking event poll, i.e with timeout = 0. If this returns events, pick one */ - if (!oversubscribed) + if (!oversubscribed && !threadpool_dedicated_listener) { - native_event ev[MAX_EVENTS]; int cnt = io_poll_wait(thread_group->pollfd, ev, MAX_EVENTS, 0); + TP_INCREMENT_GROUP_COUNTER(thread_group, polls[(int)operation_origin::WORKER]); if (cnt > 0) { queue_put(thread_group, ev, cnt); - connection= queue_get(thread_group); + connection= queue_get(thread_group,operation_origin::WORKER); break; } } - /* And now, finally sleep */ + /* And now, finally sleep */ current_thread->woken = false; /* wake() sets this to true */ - /* + /* Add current thread to the head of the waiting list and wait. It is important to add thread to the head rather than tail as it ensures LIFO wakeup order (hot caches, working inactivity timeout) */ thread_group->waiting_threads.push_front(current_thread); - + thread_group->active_thread_count--; if (abstime) { - err = mysql_cond_timedwait(¤t_thread->cond, &thread_group->mutex, + err = mysql_cond_timedwait(¤t_thread->cond, &thread_group->mutex, abstime); } else @@ -1299,7 +1249,7 @@ TP_connection_generic *get_event(worker_thread_t *current_thread, err = mysql_cond_wait(¤t_thread->cond, &thread_group->mutex); } thread_group->active_thread_count++; - + if (!current_thread->woken) { /* @@ -1315,15 +1265,16 @@ TP_connection_generic *get_event(worker_thread_t *current_thread, } thread_group->stalled= false; + mysql_mutex_unlock(&thread_group->mutex); - + DBUG_RETURN(connection); } /** - Tells the pool that worker starts waiting on IO, lock, condition, + Tells the pool that worker starts waiting on IO, lock, condition, sleep() or similar. */ @@ -1332,20 +1283,20 @@ void wait_begin(thread_group_t *thread_group) DBUG_ENTER("wait_begin"); mysql_mutex_lock(&thread_group->mutex); thread_group->active_thread_count--; - + DBUG_ASSERT(thread_group->active_thread_count >=0); DBUG_ASSERT(thread_group->connection_count > 0); - if ((thread_group->active_thread_count == 0) && + if ((thread_group->active_thread_count == 0) && (!is_queue_empty(thread_group) || !thread_group->listener)) { - /* - Group might stall while this thread waits, thus wake + /* + Group might stall while this thread waits, thus wake or create a worker to prevent stall. */ wake_or_create_thread(thread_group); } - + mysql_mutex_unlock(&thread_group->mutex); DBUG_VOID_RETURN; } @@ -1364,15 +1315,13 @@ void wait_end(thread_group_t *thread_group) } - - TP_connection * TP_pool_generic::new_connection(CONNECT *c) { return new (std::nothrow) TP_connection_generic(c); } /** - Add a new connection to thread pool.. + Add a new connection to thread pool */ void TP_pool_generic::add(TP_connection *c) @@ -1382,7 +1331,7 @@ void TP_pool_generic::add(TP_connection *c) TP_connection_generic *connection=(TP_connection_generic *)c; thread_group_t *thread_group= connection->thread_group; /* - Add connection to the work queue.Actual logon + Add connection to the work queue.Actual logon will be done by a worker thread. */ mysql_mutex_lock(&thread_group->mutex); @@ -1413,8 +1362,8 @@ void TP_connection_generic::wait_begin(int type) MySQL scheduler callback: wait end */ -void TP_connection_generic::wait_end() -{ +void TP_connection_generic::wait_end() +{ DBUG_ENTER("wait_end"); DBUG_ASSERT(waiting); waiting--; @@ -1439,6 +1388,12 @@ static void set_next_timeout_check(ulonglong abstime) DBUG_VOID_RETURN; } +static size_t get_group_id(my_thread_id tid) +{ + return size_t(tid % group_count); +} + + TP_connection_generic::TP_connection_generic(CONNECT *c): TP_connection(c), thread_group(0), @@ -1446,25 +1401,27 @@ TP_connection_generic::TP_connection_generic(CONNECT *c): prev_in_queue(0), abs_wait_timeout(ULONGLONG_MAX), bound_to_poll_descriptor(false), - waiting(false) + waiting(false), + fix_group(false) #ifdef HAVE_IOCP , overlapped() #endif +#ifdef _WIN32 +, vio_type(c->vio_type) +#endif { - DBUG_ASSERT(c->vio); + DBUG_ASSERT(c->vio_type != VIO_CLOSED); #ifdef _WIN32 - vio_type= c->vio->type; - fd= (vio_type == VIO_TYPE_NAMEDPIPE) ? - c->vio->hPipe: (TP_file_handle)mysql_socket_getfd(c->vio->mysql_socket); + fd= (c->vio_type == VIO_TYPE_NAMEDPIPE) ? + c->pipe: (TP_file_handle) mysql_socket_getfd(c->sock); #else - fd= mysql_socket_getfd(c->vio->mysql_socket); + fd= mysql_socket_getfd(c->sock); #endif /* Assign connection to a group. */ thread_group_t *group= - &all_groups[c->thread_id%group_count]; - + &all_groups[get_group_id(c->thread_id)]; thread_group=group; mysql_mutex_lock(&group->mutex); @@ -1480,17 +1437,17 @@ TP_connection_generic::~TP_connection_generic() } /** - Set wait timeout for connection. + Set wait timeout for connection. */ void TP_connection_generic::set_io_timeout(int timeout_sec) { DBUG_ENTER("set_wait_timeout"); - /* + /* Calculate wait deadline for this connection. - Instead of using microsecond_interval_timer() which has a syscall - overhead, use pool_timer.current_microtime and take - into account that its value could be off by at most + Instead of using microsecond_interval_timer() which has a syscall + overhead, use pool_timer.current_microtime and take + into account that its value could be off by at most one tick interval. */ @@ -1503,17 +1460,16 @@ void TP_connection_generic::set_io_timeout(int timeout_sec) } -#ifndef HAVE_IOCP /** - Handle a (rare) special case,where connection needs to + Handle a (rare) special case,where connection needs to migrate to a different group because group_count has changed - after thread_pool_size setting. + after thread_pool_size setting. */ -static int change_group(TP_connection_generic *c, +static int change_group(TP_connection_generic *c, thread_group_t *old_group, thread_group_t *new_group) -{ +{ int ret= 0; DBUG_ASSERT(c->thread_group == old_group); @@ -1527,22 +1483,21 @@ static int change_group(TP_connection_generic *c, } c->thread_group->connection_count--; mysql_mutex_unlock(&old_group->mutex); - + /* Add connection to the new group. */ mysql_mutex_lock(&new_group->mutex); c->thread_group= new_group; new_group->connection_count++; /* Ensure that there is a listener in the new group. */ if (!new_group->thread_count) - ret= create_worker(new_group); + ret= create_worker(new_group, false); mysql_mutex_unlock(&new_group->mutex); return ret; } -#endif + int TP_connection_generic::start_io() { -#ifndef HAVE_IOCP /* Usually, connection will stay in the same group for the entire connection's life. However, we do allow group_count to @@ -1552,26 +1507,28 @@ int TP_connection_generic::start_io() So we recalculate in which group the connection should be, based on thread_id and current group count, and migrate if necessary. - */ - thread_group_t *group = - &all_groups[thd->thread_id%group_count]; - - if (group != thread_group) + */ + if (fix_group) { - if (change_group(this, thread_group, group)) - return -1; + fix_group = false; + thread_group_t *new_group= &all_groups[get_group_id(thd->thread_id)]; + + if (new_group != thread_group) + { + if (change_group(this, thread_group, new_group)) + return -1; + } } -#endif - /* - Bind to poll descriptor if not yet done. - */ + /* + Bind to poll descriptor if not yet done. + */ if (!bound_to_poll_descriptor) { bound_to_poll_descriptor= true; return io_poll_associate_fd(thread_group->pollfd, fd, this, OPTIONAL_IO_POLL_READ_PARAM); } - + return io_poll_start_read(thread_group->pollfd, fd, this, OPTIONAL_IO_POLL_READ_PARAM); } @@ -1583,13 +1540,13 @@ int TP_connection_generic::start_io() static void *worker_main(void *param) { - + worker_thread_t this_thread; pthread_detach_this_thread(); my_thread_init(); - + DBUG_ENTER("worker_main"); - + thread_group_t *thread_group = (thread_group_t *)param; /* Init per-thread structure */ @@ -1636,18 +1593,22 @@ int TP_pool_generic::init() DBUG_ENTER("TP_pool_generic::TP_pool_generic"); threadpool_max_size= MY_MAX(threadpool_size, 128); all_groups= (thread_group_t *) - my_malloc(sizeof(thread_group_t) * threadpool_max_size, MYF(MY_WME|MY_ZEROFILL)); + my_malloc(PSI_INSTRUMENT_ME, + sizeof(thread_group_t) * threadpool_max_size, MYF(MY_WME|MY_ZEROFILL)); if (!all_groups) { threadpool_max_size= 0; sql_print_error("Allocation failed"); DBUG_RETURN(-1); } + PSI_register(mutex); + PSI_register(cond); + PSI_register(thread); scheduler_init(); threadpool_started= true; for (uint i= 0; i < threadpool_max_size; i++) { - thread_group_init(&all_groups[i], get_connection_attrib()); + thread_group_init(&all_groups[i], get_connection_attrib()); } set_pool_size(threadpool_size); if(group_count == 0) @@ -1656,10 +1617,6 @@ int TP_pool_generic::init() sql_print_error("Can't set threadpool size to %d",threadpool_size); DBUG_RETURN(-1); } - PSI_register(mutex); - PSI_register(cond); - PSI_register(thread); - pool_timer.tick_interval= threadpool_stall_limit; start_timer(&pool_timer); DBUG_RETURN(0); @@ -1668,7 +1625,7 @@ int TP_pool_generic::init() TP_pool_generic::~TP_pool_generic() { DBUG_ENTER("tp_end"); - + if (!threadpool_started) DBUG_VOID_RETURN; @@ -1691,11 +1648,19 @@ TP_pool_generic::~TP_pool_generic() } +static my_bool thd_reset_group(THD* thd, void*) +{ + auto c= (TP_connection_generic*)thd->event_scheduler.data; + if(c) + c->fix_group= true; + return FALSE; +} + /** Ensure that poll descriptors are created when threadpool_size changes */ int TP_pool_generic::set_pool_size(uint size) { bool success= true; - + for(uint i=0; i< size; i++) { thread_group_t *group= &all_groups[i]; @@ -1708,7 +1673,7 @@ int TP_pool_generic::set_pool_size(uint size) { sql_print_error("io_poll_create() failed, errno=%d", errno); } - } + } mysql_mutex_unlock(&group->mutex); if (!success) { @@ -1717,6 +1682,7 @@ int TP_pool_generic::set_pool_size(uint size) } } group_count= size; + server_threads.iterate(thd_reset_group); return 0; } @@ -1732,8 +1698,8 @@ int TP_pool_generic::set_stall_limit(uint limit) /** Calculate number of idle/waiting threads in the pool. - - Sum idle threads over all groups. + + Sum idle threads over all groups. Don't do any locking, it is not required for stats. */ @@ -1750,7 +1716,7 @@ int TP_pool_generic::get_idle_thread_count() /* Report threadpool problems */ -/** +/** Delay in microseconds, after which "pool blocked" message is printed. (30 sec == 30 Mio usec) */ @@ -1779,7 +1745,7 @@ static void print_pool_blocked_message(bool max_threads_reached) { ulonglong now; static bool msg_written; - + now= microsecond_interval_timer(); if (pool_block_start == 0) { @@ -1787,14 +1753,14 @@ static void print_pool_blocked_message(bool max_threads_reached) msg_written = false; return; } - + if (now > pool_block_start + BLOCK_MSG_DELAY && !msg_written) { if (max_threads_reached) sql_print_error(MAX_THREADS_REACHED_MSG); else sql_print_error(CREATE_THREAD_ERROR_MSG, my_errno); - + sql_print_information("Threadpool has been blocked for %u seconds\n", (uint)((now- pool_block_start)/1000000)); /* avoid reperated messages for the same blocking situation */ |