Mercurial > hg > nginx-quic
view src/event/modules/ngx_devpoll_module.c @ 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 | ab353d7dc182 |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> #if (NGX_TEST_BUILD_DEVPOLL) /* Solaris declarations */ #define POLLREMOVE 0x0800 #define DP_POLL 0xD001 #define DP_ISPOLLED 0xD002 struct dvpoll { struct pollfd *dp_fds; int dp_nfds; int dp_timeout; }; #endif typedef struct { ngx_uint_t changes; ngx_uint_t events; } ngx_devpoll_conf_t; static ngx_int_t ngx_devpoll_init(ngx_cycle_t *cycle, ngx_msec_t timer); static void ngx_devpoll_done(ngx_cycle_t *cycle); static ngx_int_t ngx_devpoll_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_devpoll_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_devpoll_set_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_devpoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags); static void *ngx_devpoll_create_conf(ngx_cycle_t *cycle); static char *ngx_devpoll_init_conf(ngx_cycle_t *cycle, void *conf); static int dp = -1; static struct pollfd *change_list, *event_list; static ngx_uint_t nchanges, max_changes, nevents; static ngx_event_t **change_index; static ngx_str_t devpoll_name = ngx_string("/dev/poll"); static ngx_command_t ngx_devpoll_commands[] = { { ngx_string("devpoll_changes"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, 0, offsetof(ngx_devpoll_conf_t, changes), NULL }, { ngx_string("devpoll_events"), NGX_EVENT_CONF|NGX_CONF_TAKE1, ngx_conf_set_num_slot, 0, offsetof(ngx_devpoll_conf_t, events), NULL }, ngx_null_command }; ngx_event_module_t ngx_devpoll_module_ctx = { &devpoll_name, ngx_devpoll_create_conf, /* create configuration */ ngx_devpoll_init_conf, /* init configuration */ { ngx_devpoll_add_event, /* add an event */ ngx_devpoll_del_event, /* delete an event */ ngx_devpoll_add_event, /* enable an event */ ngx_devpoll_del_event, /* disable an event */ NULL, /* add an connection */ NULL, /* delete an connection */ NULL, /* process the changes */ ngx_devpoll_process_events, /* process the events */ ngx_devpoll_init, /* init the events */ ngx_devpoll_done, /* done the events */ } }; ngx_module_t ngx_devpoll_module = { NGX_MODULE_V1, &ngx_devpoll_module_ctx, /* module context */ ngx_devpoll_commands, /* module directives */ NGX_EVENT_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_int_t ngx_devpoll_init(ngx_cycle_t *cycle, ngx_msec_t timer) { size_t n; ngx_devpoll_conf_t *dpcf; dpcf = ngx_event_get_conf(cycle->conf_ctx, ngx_devpoll_module); if (dp == -1) { dp = open("/dev/poll", O_RDWR); if (dp == -1) { ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno, "open(/dev/poll) failed"); return NGX_ERROR; } } if (max_changes < dpcf->changes) { if (nchanges) { n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } if (change_list) { ngx_free(change_list); } change_list = ngx_alloc(sizeof(struct pollfd) * dpcf->changes, cycle->log); if (change_list == NULL) { return NGX_ERROR; } if (change_index) { ngx_free(change_index); } change_index = ngx_alloc(sizeof(ngx_event_t *) * dpcf->changes, cycle->log); if (change_index == NULL) { return NGX_ERROR; } } max_changes = dpcf->changes; if (nevents < dpcf->events) { if (event_list) { ngx_free(event_list); } event_list = ngx_alloc(sizeof(struct pollfd) * dpcf->events, cycle->log); if (event_list == NULL) { return NGX_ERROR; } } nevents = dpcf->events; ngx_io = ngx_os_io; ngx_event_actions = ngx_devpoll_module_ctx.actions; ngx_event_flags = NGX_USE_LEVEL_EVENT|NGX_USE_FD_EVENT; return NGX_OK; } static void ngx_devpoll_done(ngx_cycle_t *cycle) { if (close(dp) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "close(/dev/poll) failed"); } dp = -1; ngx_free(change_list); ngx_free(event_list); ngx_free(change_index); change_list = NULL; event_list = NULL; change_index = NULL; max_changes = 0; nchanges = 0; nevents = 0; } static ngx_int_t ngx_devpoll_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { #if (NGX_DEBUG) ngx_connection_t *c; #endif #if (NGX_READ_EVENT != POLLIN) event = (event == NGX_READ_EVENT) ? POLLIN : POLLOUT; #endif #if (NGX_DEBUG) c = ev->data; ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "devpoll add event: fd:%d ev:%04Xi", c->fd, event); #endif ev->active = 1; return ngx_devpoll_set_event(ev, event, 0); } static ngx_int_t ngx_devpoll_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { ngx_event_t *e; ngx_connection_t *c; c = ev->data; #if (NGX_READ_EVENT != POLLIN) event = (event == NGX_READ_EVENT) ? POLLIN : POLLOUT; #endif ngx_log_debug2(NGX_LOG_DEBUG_EVENT, ev->log, 0, "devpoll del event: fd:%d ev:%04Xi", c->fd, event); if (ngx_devpoll_set_event(ev, POLLREMOVE, flags) == NGX_ERROR) { return NGX_ERROR; } ev->active = 0; if (flags & NGX_CLOSE_EVENT) { e = (event == POLLIN) ? c->write : c->read; if (e) { e->active = 0; } return NGX_OK; } /* restore the pair event if it exists */ if (event == POLLIN) { e = c->write; event = POLLOUT; } else { e = c->read; event = POLLIN; } if (e && e->active) { return ngx_devpoll_set_event(e, event, 0); } return NGX_OK; } static ngx_int_t ngx_devpoll_set_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { size_t n; ngx_connection_t *c; c = ev->data; ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ev->log, 0, "devpoll fd:%d ev:%04Xi fl:%04Xi", c->fd, event, flags); if (nchanges >= max_changes) { ngx_log_error(NGX_LOG_WARN, ev->log, 0, "/dev/pool change list is filled up"); n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } change_list[nchanges].fd = c->fd; change_list[nchanges].events = (short) event; change_list[nchanges].revents = 0; change_index[nchanges] = ev; ev->index = nchanges; nchanges++; if (flags & NGX_CLOSE_EVENT) { n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } return NGX_OK; } ngx_int_t ngx_devpoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags) { int events, revents, rc; size_t n; ngx_fd_t fd; ngx_err_t err; ngx_int_t i; ngx_uint_t level; ngx_event_t *rev, *wev, **queue; ngx_connection_t *c; struct pollfd pfd; struct dvpoll dvp; /* NGX_TIMER_INFINITE == INFTIM */ ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "devpoll timer: %M", timer); if (nchanges) { n = nchanges * sizeof(struct pollfd); if (write(dp, change_list, n) != (ssize_t) n) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "write(/dev/poll) failed"); return NGX_ERROR; } nchanges = 0; } dvp.dp_fds = event_list; dvp.dp_nfds = (int) nevents; dvp.dp_timeout = timer; events = ioctl(dp, DP_POLL, &dvp); err = (events == -1) ? ngx_errno : 0; if (flags & NGX_UPDATE_TIME || ngx_event_timer_alarm) { ngx_time_update(); } if (err) { if (err == NGX_EINTR) { if (ngx_event_timer_alarm) { ngx_event_timer_alarm = 0; return NGX_OK; } level = NGX_LOG_INFO; } else { level = NGX_LOG_ALERT; } ngx_log_error(level, cycle->log, err, "ioctl(DP_POLL) failed"); return NGX_ERROR; } if (events == 0) { if (timer != NGX_TIMER_INFINITE) { return NGX_OK; } ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "ioctl(DP_POLL) returned no events without timeout"); return NGX_ERROR; } ngx_mutex_lock(ngx_posted_events_mutex); for (i = 0; i < events; i++) { fd = event_list[i].fd; revents = event_list[i].revents; c = ngx_cycle->files[fd]; if (c == NULL || c->fd == -1) { pfd.fd = fd; pfd.events = 0; pfd.revents = 0; rc = ioctl(dp, DP_ISPOLLED, &pfd); switch (rc) { case -1: ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "ioctl(DP_ISPOLLED) failed for socket %d, event", fd, revents); break; case 0: ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "phantom event %04Xd for closed and removed socket %d", revents, fd); break; default: ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "unexpected event %04Xd for closed and removed socket %d, ", "ioctl(DP_ISPOLLED) returned rc:%d, fd:%d, event %04Xd", revents, fd, rc, pfd.fd, pfd.revents); pfd.fd = fd; pfd.events = POLLREMOVE; pfd.revents = 0; if (write(dp, &pfd, sizeof(struct pollfd)) != (ssize_t) sizeof(struct pollfd)) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "write(/dev/poll) for %d failed, fd"); } if (close(fd) == -1) { ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno, "close(%d) failed", fd); } break; } continue; } ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "devpoll: fd:%d, ev:%04Xd, rev:%04Xd", fd, event_list[i].events, revents); if (revents & (POLLERR|POLLHUP|POLLNVAL)) { ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "ioctl(DP_POLL) error fd:%d ev:%04Xd rev:%04Xd", fd, event_list[i].events, revents); } if (revents & ~(POLLIN|POLLOUT|POLLERR|POLLHUP|POLLNVAL)) { ngx_log_error(NGX_LOG_ALERT, cycle->log, 0, "strange ioctl(DP_POLL) events " "fd:%d ev:%04Xd rev:%04Xd", fd, event_list[i].events, revents); } if ((revents & (POLLERR|POLLHUP|POLLNVAL)) && (revents & (POLLIN|POLLOUT)) == 0) { /* * if the error events were returned without POLLIN or POLLOUT, * then add these flags to handle the events at least in one * active handler */ revents |= POLLIN|POLLOUT; } rev = c->read; if ((revents & POLLIN) && rev->active) { if ((flags & NGX_POST_THREAD_EVENTS) && !rev->accept) { rev->posted_ready = 1; } else { rev->ready = 1; } if (flags & NGX_POST_EVENTS) { queue = (ngx_event_t **) (rev->accept ? &ngx_posted_accept_events : &ngx_posted_events); ngx_locked_post_event(rev, queue); } else { rev->handler(rev); } } wev = c->write; if ((revents & POLLOUT) && wev->active) { if (flags & NGX_POST_THREAD_EVENTS) { wev->posted_ready = 1; } else { wev->ready = 1; } if (flags & NGX_POST_EVENTS) { ngx_locked_post_event(wev, &ngx_posted_events); } else { wev->handler(wev); } } } ngx_mutex_unlock(ngx_posted_events_mutex); return NGX_OK; } static void * ngx_devpoll_create_conf(ngx_cycle_t *cycle) { ngx_devpoll_conf_t *dpcf; dpcf = ngx_palloc(cycle->pool, sizeof(ngx_devpoll_conf_t)); if (dpcf == NULL) { return NULL; } dpcf->changes = NGX_CONF_UNSET; dpcf->events = NGX_CONF_UNSET; return dpcf; } static char * ngx_devpoll_init_conf(ngx_cycle_t *cycle, void *conf) { ngx_devpoll_conf_t *dpcf = conf; ngx_conf_init_uint_value(dpcf->changes, 32); ngx_conf_init_uint_value(dpcf->events, 32); return NGX_CONF_OK; }