Mercurial > hg > nginx-quic
view src/event/ngx_event_timer.h @ 4207:4fc91bae6f83
Better recheck of dead upstream servers.
Previously nginx used to mark backend again as live as soon as fail_timeout
passes (10s by default) since last failure. On the other hand, detecting
dead backend takes up to 60s (proxy_connect_timeout) in typical situation
"backend is down and doesn't respond to any packets". This resulted in
suboptimal behaviour in the above situation (up to 23% of requests were
directed to dead backend with default settings).
More detailed description of the problem may be found here (in Russian):
http://mailman.nginx.org/pipermail/nginx-ru/2011-August/042172.html
Fix is to only allow one request after fail_timeout passes, and
mark backend as "live" only if this request succeeds.
Note that with new code backend will not be marked "live" unless "check"
request is completed, and this may take a while in some specific workloads
(e.g. streaming). This is believed to be acceptable.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Wed, 12 Oct 2011 14:22:48 +0000 |
parents | 1739becf3f83 |
children | d620f497c50f |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev */ #ifndef _NGX_EVENT_TIMER_H_INCLUDED_ #define _NGX_EVENT_TIMER_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #define NGX_TIMER_INFINITE (ngx_msec_t) -1 #define NGX_TIMER_LAZY_DELAY 300 ngx_int_t ngx_event_timer_init(ngx_log_t *log); ngx_msec_t ngx_event_find_timer(void); void ngx_event_expire_timers(void); #if (NGX_THREADS) extern ngx_mutex_t *ngx_event_timer_mutex; #endif extern ngx_thread_volatile ngx_rbtree_t ngx_event_timer_rbtree; static ngx_inline void ngx_event_del_timer(ngx_event_t *ev) { ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "event timer del: %d: %M", ngx_event_ident(ev->data), ev->timer.key); ngx_mutex_lock(ngx_event_timer_mutex); ngx_rbtree_delete(&ngx_event_timer_rbtree, &ev->timer); ngx_mutex_unlock(ngx_event_timer_mutex); #if (NGX_DEBUG) ev->timer.left = NULL; ev->timer.right = NULL; ev->timer.parent = NULL; #endif ev->timer_set = 0; } static ngx_inline void ngx_event_add_timer(ngx_event_t *ev, ngx_msec_t timer) { ngx_msec_t key; ngx_msec_int_t diff; key = ngx_current_msec + timer; if (ev->timer_set) { /* * Use a previous timer value if difference between it and a new * value is less than NGX_TIMER_LAZY_DELAY milliseconds: this allows * to minimize the rbtree operations for fast connections. */ diff = (ngx_msec_int_t) (key - ev->timer.key); if (ngx_abs(diff) < NGX_TIMER_LAZY_DELAY) { ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ev->log, 0, "event timer: %d, old: %M, new: %M", ngx_event_ident(ev->data), ev->timer.key, key); return; } ngx_del_timer(ev); } ev->timer.key = key; ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ev->log, 0, "event timer add: %d: %M:%M", ngx_event_ident(ev->data), timer, ev->timer.key); ngx_mutex_lock(ngx_event_timer_mutex); ngx_rbtree_insert(&ngx_event_timer_rbtree, &ev->timer); ngx_mutex_unlock(ngx_event_timer_mutex); ev->timer_set = 1; } #endif /* _NGX_EVENT_TIMER_H_INCLUDED_ */