Mercurial > hg > nginx
view src/http/ngx_http_upstream_round_robin.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 | ebcee0063cd8 |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #ifndef _NGX_HTTP_UPSTREAM_ROUND_ROBIN_H_INCLUDED_ #define _NGX_HTTP_UPSTREAM_ROUND_ROBIN_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { struct sockaddr *sockaddr; socklen_t socklen; ngx_str_t name; ngx_int_t current_weight; ngx_int_t weight; ngx_uint_t fails; time_t accessed; time_t checked; ngx_uint_t max_fails; time_t fail_timeout; ngx_uint_t down; /* unsigned down:1; */ #if (NGX_HTTP_SSL) ngx_ssl_session_t *ssl_session; /* local to a process */ #endif } ngx_http_upstream_rr_peer_t; typedef struct ngx_http_upstream_rr_peers_s ngx_http_upstream_rr_peers_t; struct ngx_http_upstream_rr_peers_s { ngx_uint_t single; /* unsigned single:1; */ ngx_uint_t number; ngx_uint_t last_cached; /* ngx_mutex_t *mutex; */ ngx_connection_t **cached; ngx_str_t *name; ngx_http_upstream_rr_peers_t *next; ngx_http_upstream_rr_peer_t peer[1]; }; typedef struct { ngx_http_upstream_rr_peers_t *peers; ngx_uint_t current; uintptr_t *tried; uintptr_t data; } ngx_http_upstream_rr_peer_data_t; ngx_int_t ngx_http_upstream_init_round_robin(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us); ngx_int_t ngx_http_upstream_init_round_robin_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us); ngx_int_t ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r, ngx_http_upstream_resolved_t *ur); ngx_int_t ngx_http_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data); void ngx_http_upstream_free_round_robin_peer(ngx_peer_connection_t *pc, void *data, ngx_uint_t state); #if (NGX_HTTP_SSL) ngx_int_t ngx_http_upstream_set_round_robin_peer_session(ngx_peer_connection_t *pc, void *data); void ngx_http_upstream_save_round_robin_peer_session(ngx_peer_connection_t *pc, void *data); #endif #endif /* _NGX_HTTP_UPSTREAM_ROUND_ROBIN_H_INCLUDED_ */