Mercurial > hg > nginx-quic
view src/event/modules/ngx_aio_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 | a1d54c705f38 |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_event.h> extern ngx_event_module_t ngx_kqueue_module_ctx; static ngx_int_t ngx_aio_init(ngx_cycle_t *cycle, ngx_msec_t timer); static void ngx_aio_done(ngx_cycle_t *cycle); static ngx_int_t ngx_aio_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_aio_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags); static ngx_int_t ngx_aio_del_connection(ngx_connection_t *c, ngx_uint_t flags); static ngx_int_t ngx_aio_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags); ngx_os_io_t ngx_os_aio = { ngx_aio_read, ngx_aio_read_chain, NULL, ngx_aio_write, ngx_aio_write_chain, 0 }; static ngx_str_t aio_name = ngx_string("aio"); ngx_event_module_t ngx_aio_module_ctx = { &aio_name, NULL, /* create configuration */ NULL, /* init configuration */ { ngx_aio_add_event, /* add an event */ ngx_aio_del_event, /* delete an event */ NULL, /* enable an event */ NULL, /* disable an event */ NULL, /* add an connection */ ngx_aio_del_connection, /* delete an connection */ NULL, /* process the changes */ ngx_aio_process_events, /* process the events */ ngx_aio_init, /* init the events */ ngx_aio_done /* done the events */ } }; ngx_module_t ngx_aio_module = { NGX_MODULE_V1, &ngx_aio_module_ctx, /* module context */ NULL, /* 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 }; #if (NGX_HAVE_KQUEUE) static ngx_int_t ngx_aio_init(ngx_cycle_t *cycle, ngx_msec_t timer) { if (ngx_kqueue_module_ctx.actions.init(cycle, timer) == NGX_ERROR) { return NGX_ERROR; } ngx_io = ngx_os_aio; ngx_event_flags = NGX_USE_AIO_EVENT; ngx_event_actions = ngx_aio_module_ctx.actions; return NGX_OK; } static void ngx_aio_done(ngx_cycle_t *cycle) { ngx_kqueue_module_ctx.actions.done(cycle); } /* the event adding and deleting are needed for the listening sockets */ static ngx_int_t ngx_aio_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { return ngx_kqueue_module_ctx.actions.add(ev, event, flags); } static ngx_int_t ngx_aio_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags) { return ngx_kqueue_module_ctx.actions.del(ev, event, flags); } static ngx_int_t ngx_aio_del_connection(ngx_connection_t *c, ngx_uint_t flags) { int rc; if (c->read->active == 0 && c->write->active == 0) { return NGX_OK; } if (flags & NGX_CLOSE_EVENT) { return NGX_OK; } rc = aio_cancel(c->fd, NULL); ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0, "aio_cancel: %d", rc); if (rc == AIO_CANCELED) { c->read->active = 0; c->write->active = 0; return NGX_OK; } if (rc == AIO_ALLDONE) { c->read->active = 0; c->write->active = 0; ngx_log_error(NGX_LOG_ALERT, c->log, 0, "aio_cancel() returned AIO_ALLDONE"); return NGX_OK; } if (rc == -1) { ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno, "aio_cancel() failed"); return NGX_ERROR; } if (rc == AIO_NOTCANCELED) { ngx_log_error(NGX_LOG_ALERT, c->log, 0, "aio_cancel() returned AIO_NOTCANCELED"); return NGX_ERROR; } return NGX_OK; } static ngx_int_t ngx_aio_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags) { return ngx_kqueue_module_ctx.actions.process_events(cycle, timer, flags); } #endif /* NGX_HAVE_KQUEUE */