Mercurial > hg > nginx-quic
view src/core/ngx_shmtx.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 | 0daede16d68b |
children | 3f6040cd731e 4919fb357a5d |
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/* * Copyright (C) Igor Sysoev */ #ifndef _NGX_SHMTX_H_INCLUDED_ #define _NGX_SHMTX_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> typedef struct { #if (NGX_HAVE_ATOMIC_OPS) ngx_atomic_t *lock; #if (NGX_HAVE_POSIX_SEM) ngx_uint_t semaphore; sem_t sem; #endif #else ngx_fd_t fd; u_char *name; #endif ngx_uint_t spin; } ngx_shmtx_t; ngx_int_t ngx_shmtx_create(ngx_shmtx_t *mtx, void *addr, u_char *name); void ngx_shmtx_destory(ngx_shmtx_t *mtx); ngx_uint_t ngx_shmtx_trylock(ngx_shmtx_t *mtx); void ngx_shmtx_lock(ngx_shmtx_t *mtx); void ngx_shmtx_unlock(ngx_shmtx_t *mtx); #endif /* _NGX_SHMTX_H_INCLUDED_ */