diff options
Diffstat (limited to 'libglusterfs/src/mem-pool.c')
| -rw-r--r-- | libglusterfs/src/mem-pool.c | 201 |
1 files changed, 109 insertions, 92 deletions
diff --git a/libglusterfs/src/mem-pool.c b/libglusterfs/src/mem-pool.c index ea9cc6881b1..d77be55db5a 100644 --- a/libglusterfs/src/mem-pool.c +++ b/libglusterfs/src/mem-pool.c @@ -376,7 +376,6 @@ static __thread per_thread_pool_list_t *thread_pool_list = NULL; #define POOL_SWEEP_SECS 30 typedef struct { - struct list_head death_row; pooled_obj_hdr_t *cold_lists[N_COLD_LISTS]; unsigned int n_cold_lists; } sweep_state_t; @@ -393,36 +392,33 @@ static pthread_mutex_t init_mutex = PTHREAD_MUTEX_INITIALIZER; static unsigned int init_count = 0; static pthread_t sweeper_tid; -gf_boolean_t +static bool collect_garbage(sweep_state_t *state, per_thread_pool_list_t *pool_list) { unsigned int i; per_thread_pool_t *pt_pool; - gf_boolean_t poisoned; (void)pthread_spin_lock(&pool_list->lock); - poisoned = pool_list->poison != 0; - if (!poisoned) { - for (i = 0; i < NPOOLS; ++i) { - pt_pool = &pool_list->pools[i]; - if (pt_pool->cold_list) { - if (state->n_cold_lists >= N_COLD_LISTS) { - break; - } - state->cold_lists[state->n_cold_lists++] = pt_pool->cold_list; + for (i = 0; i < NPOOLS; ++i) { + pt_pool = &pool_list->pools[i]; + if (pt_pool->cold_list) { + if (state->n_cold_lists >= N_COLD_LISTS) { + (void)pthread_spin_unlock(&pool_list->lock); + return true; } - pt_pool->cold_list = pt_pool->hot_list; - pt_pool->hot_list = NULL; + state->cold_lists[state->n_cold_lists++] = pt_pool->cold_list; } + pt_pool->cold_list = pt_pool->hot_list; + pt_pool->hot_list = NULL; } (void)pthread_spin_unlock(&pool_list->lock); - return poisoned; + return false; } -void +static void free_obj_list(pooled_obj_hdr_t *victim) { pooled_obj_hdr_t *next; @@ -434,82 +430,96 @@ free_obj_list(pooled_obj_hdr_t *victim) } } -void * +static void * pool_sweeper(void *arg) { sweep_state_t state; per_thread_pool_list_t *pool_list; - per_thread_pool_list_t *next_pl; - per_thread_pool_t *pt_pool; - unsigned int i; - gf_boolean_t poisoned; + uint32_t i; + bool pending; /* * This is all a bit inelegant, but the point is to avoid doing * expensive things (like freeing thousands of objects) while holding a - * global lock. Thus, we split each iteration into three passes, with + * global lock. Thus, we split each iteration into two passes, with * only the first and fastest holding the lock. */ + pending = true; + for (;;) { - sleep(POOL_SWEEP_SECS); + /* If we know there's pending work to do (or it's the first run), we + * do collect garbage more often. */ + sleep(pending ? POOL_SWEEP_SECS / 5 : POOL_SWEEP_SECS); + (void)pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL); - INIT_LIST_HEAD(&state.death_row); state.n_cold_lists = 0; + pending = false; /* First pass: collect stuff that needs our attention. */ (void)pthread_mutex_lock(&pool_lock); - list_for_each_entry_safe(pool_list, next_pl, &pool_threads, thr_list) + list_for_each_entry(pool_list, &pool_threads, thr_list) { - (void)pthread_mutex_unlock(&pool_lock); - poisoned = collect_garbage(&state, pool_list); - (void)pthread_mutex_lock(&pool_lock); - - if (poisoned) { - list_move(&pool_list->thr_list, &state.death_row); + if (collect_garbage(&state, pool_list)) { + pending = true; } } (void)pthread_mutex_unlock(&pool_lock); - /* Second pass: free dead pools. */ - (void)pthread_mutex_lock(&pool_free_lock); - list_for_each_entry_safe(pool_list, next_pl, &state.death_row, thr_list) - { - for (i = 0; i < NPOOLS; ++i) { - pt_pool = &pool_list->pools[i]; - free_obj_list(pt_pool->cold_list); - free_obj_list(pt_pool->hot_list); - pt_pool->hot_list = pt_pool->cold_list = NULL; - } - list_del(&pool_list->thr_list); - list_add(&pool_list->thr_list, &pool_free_threads); - } - (void)pthread_mutex_unlock(&pool_free_lock); - - /* Third pass: free cold objects from live pools. */ + /* Second pass: free cold objects from live pools. */ for (i = 0; i < state.n_cold_lists; ++i) { free_obj_list(state.cold_lists[i]); } (void)pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL); } + + return NULL; } void -mem_pool_thread_destructor(void) +mem_pool_thread_destructor(per_thread_pool_list_t *pool_list) { - per_thread_pool_list_t *pool_list = thread_pool_list; - - /* The pool-sweeper thread will take it from here. - * - * We can change 'poison' here without taking locks because the change - * itself doesn't interact with other parts of the code and a simple write - * is already atomic from the point of view of the processor. - * - * This change can modify what mem_put() does, but both possibilities are - * fine until the sweeper thread kicks in. The real synchronization must be - * between mem_put() and the sweeper thread. */ + per_thread_pool_t *pt_pool; + uint32_t i; + + if (pool_list == NULL) { + pool_list = thread_pool_list; + } + + /* The current thread is terminating. None of the allocated objects will + * be used again. We can directly destroy them here instead of delaying + * it until the next sweeper loop. */ if (pool_list != NULL) { - pool_list->poison = 1; + /* Remove pool_list from the global list to avoid that sweeper + * could touch it. */ + pthread_mutex_lock(&pool_lock); + list_del(&pool_list->thr_list); + pthread_mutex_unlock(&pool_lock); + + /* We need to protect hot/cold changes from potential mem_put() calls + * that reference this pool_list. Once poison is set to true, we are + * sure that no one else will touch hot/cold lists. The only possible + * race is when at the same moment a mem_put() is adding a new item + * to the hot list. We protect from that by taking pool_list->lock. + * After that we don't need the lock to destroy the hot/cold lists. */ + pthread_spin_lock(&pool_list->lock); + pool_list->poison = true; + pthread_spin_unlock(&pool_list->lock); + + for (i = 0; i < NPOOLS; i++) { + pt_pool = &pool_list->pools[i]; + + free_obj_list(pt_pool->hot_list); + pt_pool->hot_list = NULL; + + free_obj_list(pt_pool->cold_list); + pt_pool->cold_list = NULL; + } + + pthread_mutex_lock(&pool_free_lock); + list_add(&pool_list->thr_list, &pool_free_threads); + pthread_mutex_unlock(&pool_free_lock); + thread_pool_list = NULL; } } @@ -537,6 +547,30 @@ mem_pools_preinit(void) init_done = GF_MEMPOOL_INIT_EARLY; } +static __attribute__((destructor)) void +mem_pools_postfini(void) +{ + per_thread_pool_list_t *pool_list, *next; + + /* This is part of a process shutdown (or dlclose()) which means that + * most probably all threads should be stopped. However this is not the + * case for gluster and there are even legitimate situations in which we + * could have some threads alive. What is sure is that none of those + * threads should be using anything from this library, so destroying + * everything here should be fine and safe. */ + + list_for_each_entry_safe(pool_list, next, &pool_threads, thr_list) + { + mem_pool_thread_destructor(pool_list); + } + + list_for_each_entry_safe(pool_list, next, &pool_free_threads, thr_list) + { + list_del(&pool_list->thr_list); + FREE(pool_list); + } +} + /* Call mem_pools_init() once threading has been configured completely. This * prevent the pool_sweeper thread from getting killed once the main() thread * exits during deamonizing. */ @@ -569,10 +603,6 @@ mem_pools_fini(void) */ break; case 1: { - per_thread_pool_list_t *pool_list; - per_thread_pool_list_t *next_pl; - unsigned int i; - /* if mem_pools_init() was not called, sweeper_tid will be invalid * and the functions will error out. That is not critical. In all * other cases, the sweeper_tid will be valid and the thread gets @@ -580,32 +610,11 @@ mem_pools_fini(void) (void)pthread_cancel(sweeper_tid); (void)pthread_join(sweeper_tid, NULL); - /* At this point all threads should have already terminated, so - * it should be safe to destroy all pending per_thread_pool_list_t - * structures that are stored for each thread. */ - mem_pool_thread_destructor(); - - /* free all objects from all pools */ - list_for_each_entry_safe(pool_list, next_pl, &pool_threads, - thr_list) - { - for (i = 0; i < NPOOLS; ++i) { - free_obj_list(pool_list->pools[i].hot_list); - free_obj_list(pool_list->pools[i].cold_list); - pool_list->pools[i].hot_list = NULL; - pool_list->pools[i].cold_list = NULL; - } - - list_del(&pool_list->thr_list); - FREE(pool_list); - } - - list_for_each_entry_safe(pool_list, next_pl, &pool_free_threads, - thr_list) - { - list_del(&pool_list->thr_list); - FREE(pool_list); - } + /* There could be threads still running in some cases, so we can't + * destroy pool_lists in use. We can also not destroy unused + * pool_lists because some allocated objects may still be pointing + * to them. */ + mem_pool_thread_destructor(NULL); init_done = GF_MEMPOOL_INIT_DESTROY; /* Fall through. */ @@ -626,7 +635,7 @@ mem_pools_fini(void) { } void -mem_pool_thread_destructor(void) +mem_pool_thread_destructor(per_thread_pool_list_t *pool_list) { } @@ -747,13 +756,21 @@ mem_get_pool_list(void) } } + /* There's no need to take pool_list->lock, because this is already an + * atomic operation and we don't need to synchronize it with any change + * in hot/cold lists. */ + pool_list->poison = false; + (void)pthread_mutex_lock(&pool_lock); - pool_list->poison = 0; list_add(&pool_list->thr_list, &pool_threads); (void)pthread_mutex_unlock(&pool_lock); thread_pool_list = pool_list; + /* Ensure that all memory objects associated to the new pool_list are + * destroyed when the thread terminates. */ + gf_thread_needs_cleanup(); + return pool_list; } |