Mercurial > hg > nginx-quic
view src/http/modules/ngx_http_upstream_keepalive_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 | b2e21a39307c |
children | d620f497c50f |
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/* * Copyright (C) Maxim Dounin */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { ngx_uint_t max_cached; ngx_uint_t single; /* unsigned:1 */ ngx_queue_t cache; ngx_queue_t free; ngx_http_upstream_init_pt original_init_upstream; ngx_http_upstream_init_peer_pt original_init_peer; } ngx_http_upstream_keepalive_srv_conf_t; typedef struct { ngx_http_upstream_keepalive_srv_conf_t *conf; ngx_http_upstream_t *upstream; void *data; ngx_event_get_peer_pt original_get_peer; ngx_event_free_peer_pt original_free_peer; #if (NGX_HTTP_SSL) ngx_event_set_peer_session_pt original_set_session; ngx_event_save_peer_session_pt original_save_session; #endif ngx_uint_t failed; /* unsigned:1 */ } ngx_http_upstream_keepalive_peer_data_t; typedef struct { ngx_http_upstream_keepalive_srv_conf_t *conf; ngx_queue_t queue; ngx_connection_t *connection; socklen_t socklen; u_char sockaddr[NGX_SOCKADDRLEN]; } ngx_http_upstream_keepalive_cache_t; static ngx_int_t ngx_http_upstream_init_keepalive_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us); static ngx_int_t ngx_http_upstream_get_keepalive_peer(ngx_peer_connection_t *pc, void *data); static void ngx_http_upstream_free_keepalive_peer(ngx_peer_connection_t *pc, void *data, ngx_uint_t state); static void ngx_http_upstream_keepalive_dummy_handler(ngx_event_t *ev); static void ngx_http_upstream_keepalive_close_handler(ngx_event_t *ev); static void ngx_http_upstream_keepalive_close(ngx_connection_t *c); #if (NGX_HTTP_SSL) static ngx_int_t ngx_http_upstream_keepalive_set_session( ngx_peer_connection_t *pc, void *data); static void ngx_http_upstream_keepalive_save_session(ngx_peer_connection_t *pc, void *data); #endif static void *ngx_http_upstream_keepalive_create_conf(ngx_conf_t *cf); static char *ngx_http_upstream_keepalive(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_command_t ngx_http_upstream_keepalive_commands[] = { { ngx_string("keepalive"), NGX_HTTP_UPS_CONF|NGX_CONF_TAKE12, ngx_http_upstream_keepalive, 0, 0, NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_upstream_keepalive_module_ctx = { NULL, /* preconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ ngx_http_upstream_keepalive_create_conf, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_upstream_keepalive_module = { NGX_MODULE_V1, &ngx_http_upstream_keepalive_module_ctx, /* module context */ ngx_http_upstream_keepalive_commands, /* module directives */ NGX_HTTP_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_http_upstream_init_keepalive(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us) { ngx_uint_t i; ngx_http_upstream_keepalive_srv_conf_t *kcf; ngx_http_upstream_keepalive_cache_t *cached; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0, "init keepalive"); kcf = ngx_http_conf_upstream_srv_conf(us, ngx_http_upstream_keepalive_module); if (kcf->original_init_upstream(cf, us) != NGX_OK) { return NGX_ERROR; } kcf->original_init_peer = us->peer.init; us->peer.init = ngx_http_upstream_init_keepalive_peer; /* allocate cache items and add to free queue */ cached = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_keepalive_cache_t) * kcf->max_cached); if (cached == NULL) { return NGX_ERROR; } ngx_queue_init(&kcf->cache); ngx_queue_init(&kcf->free); for (i = 0; i < kcf->max_cached; i++) { ngx_queue_insert_head(&kcf->free, &cached[i].queue); cached[i].conf = kcf; } return NGX_OK; } static ngx_int_t ngx_http_upstream_init_keepalive_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us) { ngx_http_upstream_keepalive_peer_data_t *kp; ngx_http_upstream_keepalive_srv_conf_t *kcf; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "init keepalive peer"); kcf = ngx_http_conf_upstream_srv_conf(us, ngx_http_upstream_keepalive_module); kp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_keepalive_peer_data_t)); if (kp == NULL) { return NGX_ERROR; } if (kcf->original_init_peer(r, us) != NGX_OK) { return NGX_ERROR; } kp->conf = kcf; kp->upstream = r->upstream; kp->data = r->upstream->peer.data; kp->original_get_peer = r->upstream->peer.get; kp->original_free_peer = r->upstream->peer.free; r->upstream->peer.data = kp; r->upstream->peer.get = ngx_http_upstream_get_keepalive_peer; r->upstream->peer.free = ngx_http_upstream_free_keepalive_peer; #if (NGX_HTTP_SSL) kp->original_set_session = r->upstream->peer.set_session; kp->original_save_session = r->upstream->peer.save_session; r->upstream->peer.set_session = ngx_http_upstream_keepalive_set_session; r->upstream->peer.save_session = ngx_http_upstream_keepalive_save_session; #endif return NGX_OK; } static ngx_int_t ngx_http_upstream_get_keepalive_peer(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_keepalive_peer_data_t *kp = data; ngx_http_upstream_keepalive_cache_t *item; ngx_int_t rc; ngx_queue_t *q, *cache; ngx_connection_t *c; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get keepalive peer"); kp->failed = 0; /* single pool of cached connections */ if (kp->conf->single && !ngx_queue_empty(&kp->conf->cache)) { q = ngx_queue_head(&kp->conf->cache); item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); c = item->connection; ngx_queue_remove(q); ngx_queue_insert_head(&kp->conf->free, q); ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get keepalive peer: using connection %p", c); c->idle = 0; c->log = pc->log; c->read->log = pc->log; c->write->log = pc->log; c->pool->log = pc->log; pc->connection = c; pc->cached = 1; return NGX_DONE; } rc = kp->original_get_peer(pc, kp->data); if (kp->conf->single || rc != NGX_OK) { return rc; } /* search cache for suitable connection */ cache = &kp->conf->cache; for (q = ngx_queue_head(cache); q != ngx_queue_sentinel(cache); q = ngx_queue_next(q)) { item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); c = item->connection; if (ngx_memn2cmp((u_char *) &item->sockaddr, (u_char *) pc->sockaddr, item->socklen, pc->socklen) == 0) { ngx_queue_remove(q); ngx_queue_insert_head(&kp->conf->free, q); ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get keepalive peer: using connection %p", c); c->idle = 0; c->log = pc->log; c->read->log = pc->log; c->write->log = pc->log; c->pool->log = pc->log; pc->connection = c; pc->cached = 1; return NGX_DONE; } } return NGX_OK; } static void ngx_http_upstream_free_keepalive_peer(ngx_peer_connection_t *pc, void *data, ngx_uint_t state) { ngx_http_upstream_keepalive_peer_data_t *kp = data; ngx_http_upstream_keepalive_cache_t *item; ngx_queue_t *q; ngx_connection_t *c; ngx_http_upstream_t *u; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "free keepalive peer"); /* remember failed state - peer.free() may be called more than once */ if (state & NGX_PEER_FAILED) { kp->failed = 1; } /* cache valid connections */ u = kp->upstream; c = pc->connection; if (kp->failed || c == NULL || c->read->eof || c->read->error || c->read->timedout || c->write->error || c->write->timedout) { goto invalid; } if (!u->keepalive) { goto invalid; } if (ngx_handle_read_event(c->read, 0) != NGX_OK) { goto invalid; } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "free keepalive peer: saving connection %p", c); if (ngx_queue_empty(&kp->conf->free)) { q = ngx_queue_last(&kp->conf->cache); ngx_queue_remove(q); item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); ngx_http_upstream_keepalive_close(item->connection); } else { q = ngx_queue_head(&kp->conf->free); ngx_queue_remove(q); item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); } item->connection = c; ngx_queue_insert_head(&kp->conf->cache, q); pc->connection = NULL; if (c->read->timer_set) { ngx_del_timer(c->read); } if (c->write->timer_set) { ngx_del_timer(c->write); } c->write->handler = ngx_http_upstream_keepalive_dummy_handler; c->read->handler = ngx_http_upstream_keepalive_close_handler; c->data = item; c->idle = 1; c->log = ngx_cycle->log; c->read->log = ngx_cycle->log; c->write->log = ngx_cycle->log; c->pool->log = ngx_cycle->log; item->socklen = pc->socklen; ngx_memcpy(&item->sockaddr, pc->sockaddr, pc->socklen); if (c->read->ready) { ngx_http_upstream_keepalive_close_handler(c->read); } invalid: kp->original_free_peer(pc, kp->data, state); } static void ngx_http_upstream_keepalive_dummy_handler(ngx_event_t *ev) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0, "keepalive dummy handler"); } static void ngx_http_upstream_keepalive_close_handler(ngx_event_t *ev) { ngx_http_upstream_keepalive_srv_conf_t *conf; ngx_http_upstream_keepalive_cache_t *item; int n; char buf[1]; ngx_connection_t *c; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0, "keepalive close handler"); c = ev->data; if (c->close) { goto close; } n = recv(c->fd, buf, 1, MSG_PEEK); if (n == -1 && ngx_socket_errno == NGX_EAGAIN) { /* stale event */ if (ngx_handle_read_event(c->read, 0) != NGX_OK) { goto close; } return; } close: item = c->data; conf = item->conf; ngx_http_upstream_keepalive_close(c); ngx_queue_remove(&item->queue); ngx_queue_insert_head(&conf->free, &item->queue); } static void ngx_http_upstream_keepalive_close(ngx_connection_t *c) { #if (NGX_HTTP_SSL) if (c->ssl) { c->ssl->no_wait_shutdown = 1; c->ssl->no_send_shutdown = 1; if (ngx_ssl_shutdown(c) == NGX_AGAIN) { c->ssl->handler = ngx_http_upstream_keepalive_close; return; } } #endif ngx_destroy_pool(c->pool); ngx_close_connection(c); } #if (NGX_HTTP_SSL) static ngx_int_t ngx_http_upstream_keepalive_set_session(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_keepalive_peer_data_t *kp = data; return kp->original_set_session(pc, kp->data); } static void ngx_http_upstream_keepalive_save_session(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_keepalive_peer_data_t *kp = data; kp->original_save_session(pc, kp->data); return; } #endif static void * ngx_http_upstream_keepalive_create_conf(ngx_conf_t *cf) { ngx_http_upstream_keepalive_srv_conf_t *conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_keepalive_srv_conf_t)); if (conf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->original_init_upstream = NULL; * conf->original_init_peer = NULL; */ conf->max_cached = 1; return conf; } static char * ngx_http_upstream_keepalive(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_upstream_srv_conf_t *uscf; ngx_http_upstream_keepalive_srv_conf_t *kcf; ngx_int_t n; ngx_str_t *value; ngx_uint_t i; uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module); kcf = ngx_http_conf_upstream_srv_conf(uscf, ngx_http_upstream_keepalive_module); kcf->original_init_upstream = uscf->peer.init_upstream ? uscf->peer.init_upstream : ngx_http_upstream_init_round_robin; uscf->peer.init_upstream = ngx_http_upstream_init_keepalive; /* read options */ value = cf->args->elts; n = ngx_atoi(value[1].data, value[1].len); if (n == NGX_ERROR || n == 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid value \"%V\" in \"%V\" directive", &value[1], &cmd->name); return NGX_CONF_ERROR; } kcf->max_cached = n; for (i = 2; i < cf->args->nelts; i++) { if (ngx_strcmp(value[i].data, "single") == 0) { kcf->single = 1; continue; } goto invalid; } return NGX_CONF_OK; invalid: ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid parameter \"%V\"", &value[i]); return NGX_CONF_ERROR; }