view src/core/ngx_cycle.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 e3cb8e27e413
children d620f497c50f
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/*
 * Copyright (C) Igor Sysoev
 */


#ifndef _NGX_CYCLE_H_INCLUDED_
#define _NGX_CYCLE_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>


#ifndef NGX_CYCLE_POOL_SIZE
#define NGX_CYCLE_POOL_SIZE     16384
#endif


#define NGX_DEBUG_POINTS_STOP   1
#define NGX_DEBUG_POINTS_ABORT  2


typedef struct ngx_shm_zone_s  ngx_shm_zone_t;

typedef ngx_int_t (*ngx_shm_zone_init_pt) (ngx_shm_zone_t *zone, void *data);

struct ngx_shm_zone_s {
    void                     *data;
    ngx_shm_t                 shm;
    ngx_shm_zone_init_pt      init;
    void                     *tag;
};


struct ngx_cycle_s {
    void                  ****conf_ctx;
    ngx_pool_t               *pool;

    ngx_log_t                *log;
    ngx_log_t                 new_log;

    ngx_connection_t        **files;
    ngx_connection_t         *free_connections;
    ngx_uint_t                free_connection_n;

    ngx_queue_t               reusable_connections_queue;

    ngx_array_t               listening;
    ngx_array_t               pathes;
    ngx_list_t                open_files;
    ngx_list_t                shared_memory;

    ngx_uint_t                connection_n;
    ngx_uint_t                files_n;

    ngx_connection_t         *connections;
    ngx_event_t              *read_events;
    ngx_event_t              *write_events;

    ngx_cycle_t              *old_cycle;

    ngx_str_t                 conf_file;
    ngx_str_t                 conf_param;
    ngx_str_t                 conf_prefix;
    ngx_str_t                 prefix;
    ngx_str_t                 lock_file;
    ngx_str_t                 hostname;
};


typedef struct {
     ngx_flag_t               daemon;
     ngx_flag_t               master;

     ngx_msec_t               timer_resolution;

     ngx_int_t                worker_processes;
     ngx_int_t                debug_points;

     ngx_int_t                rlimit_nofile;
     ngx_int_t                rlimit_sigpending;
     off_t                    rlimit_core;

     int                      priority;

     ngx_uint_t               cpu_affinity_n;
     u_long                  *cpu_affinity;

     char                    *username;
     ngx_uid_t                user;
     ngx_gid_t                group;

     ngx_str_t                working_directory;
     ngx_str_t                lock_file;

     ngx_str_t                pid;
     ngx_str_t                oldpid;

     ngx_array_t              env;
     char                   **environment;

#if (NGX_THREADS)
     ngx_int_t                worker_threads;
     size_t                   thread_stack_size;
#endif

} ngx_core_conf_t;


typedef struct {
     ngx_pool_t              *pool;   /* pcre's malloc() pool */
} ngx_core_tls_t;


#define ngx_is_init_cycle(cycle)  (cycle->conf_ctx == NULL)


ngx_cycle_t *ngx_init_cycle(ngx_cycle_t *old_cycle);
ngx_int_t ngx_create_pidfile(ngx_str_t *name, ngx_log_t *log);
void ngx_delete_pidfile(ngx_cycle_t *cycle);
ngx_int_t ngx_signal_process(ngx_cycle_t *cycle, char *sig);
void ngx_reopen_files(ngx_cycle_t *cycle, ngx_uid_t user);
char **ngx_set_environment(ngx_cycle_t *cycle, ngx_uint_t *last);
ngx_pid_t ngx_exec_new_binary(ngx_cycle_t *cycle, char *const *argv);
u_long ngx_get_cpu_affinity(ngx_uint_t n);
ngx_shm_zone_t *ngx_shared_memory_add(ngx_conf_t *cf, ngx_str_t *name,
    size_t size, void *tag);


extern volatile ngx_cycle_t  *ngx_cycle;
extern ngx_array_t            ngx_old_cycles;
extern ngx_module_t           ngx_core_module;
extern ngx_uint_t             ngx_test_config;
extern ngx_uint_t             ngx_quiet_mode;
#if (NGX_THREADS)
extern ngx_tls_key_t          ngx_core_tls_key;
#endif


#endif /* _NGX_CYCLE_H_INCLUDED_ */