From 403bfbb130f9fb31e52d441ebc1f8227f6883c22 Mon Sep 17 00:00:00 2001 From: Willy Tarreau Date: Wed, 23 Oct 2019 06:59:31 +0200 Subject: [PATCH] BUG/MEDIUM: pattern: make the pattern LRU cache thread-local and lockless As reported in issue #335, a lot of contention happens on the PATLRU lock when performing expensive regex lookups. This is absurd since the purpose of the LRU cache was to have a fast cache for expressions, thus the cache must not be shared between threads and must remain lockless. This commit makes the LRU cache thread-local and gets rid of the PATLRU lock. A test with 7 threads on 4 cores climbed from 67kH/s to 369kH/s, or a scalability factor of 5.5. Given the huge performance difference and the regression caused to users migrating from processes to threads, this should be backported at least to 2.0. Thanks to Brian Diekelman for his detailed report about this regression. --- doc/configuration.txt | 3 +- include/common/hathreads.h | 2 - src/pattern.c | 88 +++++++++++++------------------------- 3 files changed, 31 insertions(+), 62 deletions(-) diff --git a/doc/configuration.txt b/doc/configuration.txt index b79795c68..d8e1b57f1 100644 --- a/doc/configuration.txt +++ b/doc/configuration.txt @@ -1845,7 +1845,8 @@ tune.pattern.cache-size configuration line (including all those loaded from files). It automatically invalidates entries which are updated using HTTP actions or on the CLI. The default cache size is set to 10000 entries, which limits its footprint to - about 5 MB on 32-bit systems and 8 MB on 64-bit systems. There is a very low + about 5 MB per process/thread on 32-bit systems and 8 MB per process/thread + on 64-bit systems, as caches are thread/process local. There is a very low risk of collision in this cache, which is in the order of the size of the cache divided by 2^64. Typically, at 10000 requests per second with the default cache size of 10000 entries, there's 1% chance that a brute force diff --git a/include/common/hathreads.h b/include/common/hathreads.h index 02568de12..daef3a440 100644 --- a/include/common/hathreads.h +++ b/include/common/hathreads.h @@ -548,7 +548,6 @@ enum lock_label { SSL_GEN_CERTS_LOCK, PATREF_LOCK, PATEXP_LOCK, - PATLRU_LOCK, VARS_LOCK, COMP_POOL_LOCK, LUA_LOCK, @@ -668,7 +667,6 @@ static inline const char *lock_label(enum lock_label label) case SSL_GEN_CERTS_LOCK: return "SSL_GEN_CERTS"; case PATREF_LOCK: return "PATREF"; case PATEXP_LOCK: return "PATEXP"; - case PATLRU_LOCK: return "PATLRU"; case VARS_LOCK: return "VARS"; case COMP_POOL_LOCK: return "COMP_POOL"; case LUA_LOCK: return "LUA"; diff --git a/src/pattern.c b/src/pattern.c index 6bf0c945c..ec7e9556a 100644 --- a/src/pattern.c +++ b/src/pattern.c @@ -154,8 +154,7 @@ static THREAD_LOCAL struct sample_data static_sample_data; /* This is the root of the list of all pattern_ref avalaibles. */ struct list pattern_reference = LIST_HEAD_INIT(pattern_reference); -static struct lru64_head *pat_lru_tree; -__decl_spinlock(pat_lru_tree_lock); +static THREAD_LOCAL struct lru64_head *pat_lru_tree; static unsigned long long pat_lru_seed; /* @@ -487,15 +486,10 @@ struct pattern *pat_match_str(struct sample *smp, struct pattern_expr *expr, int if (pat_lru_tree) { unsigned long long seed = pat_lru_seed ^ (long)expr; - HA_SPIN_LOCK(PATLRU_LOCK, &pat_lru_tree_lock); lru = lru64_get(XXH64(smp->data.u.str.area, smp->data.u.str.data, seed), pat_lru_tree, expr, expr->revision); - if (!lru) { - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } - else if (lru->domain) { + if (lru && lru->domain) { ret = lru->data; - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); return ret; } } @@ -515,10 +509,8 @@ struct pattern *pat_match_str(struct sample *smp, struct pattern_expr *expr, int } } - if (lru) { + if (lru) lru64_commit(lru, ret, expr, expr->revision, NULL); - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } return ret; } @@ -534,15 +526,10 @@ struct pattern *pat_match_bin(struct sample *smp, struct pattern_expr *expr, int if (pat_lru_tree) { unsigned long long seed = pat_lru_seed ^ (long)expr; - HA_SPIN_LOCK(PATLRU_LOCK, &pat_lru_tree_lock); lru = lru64_get(XXH64(smp->data.u.str.area, smp->data.u.str.data, seed), pat_lru_tree, expr, expr->revision); - if (!lru) { - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } - else if (lru->domain) { + if (lru && lru->domain) { ret = lru->data; - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); return ret; } } @@ -559,10 +546,8 @@ struct pattern *pat_match_bin(struct sample *smp, struct pattern_expr *expr, int } } - if (lru) { + if (lru) lru64_commit(lru, ret, expr, expr->revision, NULL); - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } return ret; } @@ -604,15 +589,10 @@ struct pattern *pat_match_reg(struct sample *smp, struct pattern_expr *expr, int if (pat_lru_tree) { unsigned long long seed = pat_lru_seed ^ (long)expr; - HA_SPIN_LOCK(PATLRU_LOCK, &pat_lru_tree_lock); lru = lru64_get(XXH64(smp->data.u.str.area, smp->data.u.str.data, seed), pat_lru_tree, expr, expr->revision); - if (!lru) { - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } - else if (lru->domain) { + if (lru && lru->domain) { ret = lru->data; - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); return ret; } } @@ -626,10 +606,8 @@ struct pattern *pat_match_reg(struct sample *smp, struct pattern_expr *expr, int } } - if (lru) { + if (lru) lru64_commit(lru, ret, expr, expr->revision, NULL); - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } return ret; } @@ -674,15 +652,10 @@ struct pattern *pat_match_beg(struct sample *smp, struct pattern_expr *expr, int if (pat_lru_tree) { unsigned long long seed = pat_lru_seed ^ (long)expr; - HA_SPIN_LOCK(PATLRU_LOCK, &pat_lru_tree_lock); lru = lru64_get(XXH64(smp->data.u.str.area, smp->data.u.str.data, seed), pat_lru_tree, expr, expr->revision); - if (!lru) { - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } - else if (lru->domain) { + if (lru && lru->domain) { ret = lru->data; - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); return ret; } } @@ -702,10 +675,8 @@ struct pattern *pat_match_beg(struct sample *smp, struct pattern_expr *expr, int break; } - if (lru) { + if (lru) lru64_commit(lru, ret, expr, expr->revision, NULL); - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } return ret; } @@ -722,15 +693,10 @@ struct pattern *pat_match_end(struct sample *smp, struct pattern_expr *expr, int if (pat_lru_tree) { unsigned long long seed = pat_lru_seed ^ (long)expr; - HA_SPIN_LOCK(PATLRU_LOCK, &pat_lru_tree_lock); lru = lru64_get(XXH64(smp->data.u.str.area, smp->data.u.str.data, seed), pat_lru_tree, expr, expr->revision); - if (!lru) { - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } - else if (lru->domain) { + if (lru && lru->domain) { ret = lru->data; - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); return ret; } } @@ -750,10 +716,8 @@ struct pattern *pat_match_end(struct sample *smp, struct pattern_expr *expr, int break; } - if (lru) { + if (lru) lru64_commit(lru, ret, expr, expr->revision, NULL); - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } return ret; } @@ -774,15 +738,10 @@ struct pattern *pat_match_sub(struct sample *smp, struct pattern_expr *expr, int if (pat_lru_tree) { unsigned long long seed = pat_lru_seed ^ (long)expr; - HA_SPIN_LOCK(PATLRU_LOCK, &pat_lru_tree_lock); lru = lru64_get(XXH64(smp->data.u.str.area, smp->data.u.str.data, seed), pat_lru_tree, expr, expr->revision); - if (!lru) { - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } - else if (lru->domain) { + if (lru && lru->domain) { ret = lru->data; - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); return ret; } } @@ -816,10 +775,8 @@ struct pattern *pat_match_sub(struct sample *smp, struct pattern_expr *expr, int } } leave: - if (lru) { + if (lru) lru64_commit(lru, ret, expr, expr->revision, NULL); - HA_SPIN_UNLOCK(PATLRU_LOCK, &pat_lru_tree_lock); - } return ret; } @@ -2685,9 +2642,6 @@ void pattern_finalize_config(void) struct list pr = LIST_HEAD_INIT(pr); pat_lru_seed = random(); - if (global.tune.pattern_cache) { - pat_lru_tree = lru64_new(global.tune.pattern_cache); - } list_for_each_entry(ref, &pattern_reference, list) { if (ref->unique_id == -1) { @@ -2726,3 +2680,19 @@ void pattern_finalize_config(void) LIST_ADD(&pr, &pattern_reference); LIST_DEL(&pr); } + +static int pattern_per_thread_lru_alloc() +{ + if (!global.tune.pattern_cache) + return 1; + pat_lru_tree = lru64_new(global.tune.pattern_cache); + return !!pat_lru_tree; +} + +static void pattern_per_thread_lru_free() +{ + lru64_destroy(pat_lru_tree); +} + +REGISTER_PER_THREAD_ALLOC(pattern_per_thread_lru_alloc); +REGISTER_PER_THREAD_FREE(pattern_per_thread_lru_free);