Author: mdounin
Date: 2012-05-11 13:33:06 +0000 (Fri, 11 May 2012)
New Revision: 4619
URL: http://trac.nginx.org/nginx/changeset/4619/nginx

Log:
Accept moderation in case of EMFILE/ENFILE.

In case of EMFILE/ENFILE returned from accept() we disable accept events,
and (in case of no accept mutex used) arm timer to re-enable them later.
With accept mutex we just drop it, and rely on normal accept mutex handling
to re-enable accept events once it's acquired again.

As we now handle errors in question, logging level was changed to "crit"
(instead of "alert" used for unknown errors).

Note: the code might call ngx_enable_accept_events() multiple times if
there are many listen sockets. The ngx_enable_accept_events() function was
modified to check if connection is already active (via c->read->active) and
skip it then, thus making multiple calls safe.


Modified:
trunk/src/event/ngx_event_accept.c
trunk/src/os/unix/ngx_errno.h
trunk/src/os/win32/ngx_errno.h

Modified: trunk/src/event/ngx_event_accept.c
===================================================================
--- trunk/src/event/ngx_event_accept.c 2012-05-11 13:19:22 UTC (rev 4618)
+++ trunk/src/event/ngx_event_accept.c 2012-05-11 13:33:06 UTC (rev 4619)
@@ -21,6 +21,7 @@
socklen_t socklen;
ngx_err_t err;
ngx_log_t *log;
+ ngx_uint_t level;
ngx_socket_t s;
ngx_event_t *rev, *wev;
ngx_listening_t *ls;
@@ -31,6 +32,14 @@
static ngx_uint_t use_accept4 = 1;
#endif

+ if (ev->timedout) {
+ if (ngx_enable_accept_events((ngx_cycle_t *) ngx_cycle) != NGX_OK) {
+ return;
+ }
+
+ ev->timedout = 0;
+ }
+
ecf = ngx_event_get_conf(ngx_cycle->conf_ctx, ngx_event_core_module);

if (ngx_event_flags & NGX_USE_RTSIG_EVENT) {
@@ -70,10 +79,17 @@
return;
}

+ level = NGX_LOG_ALERT;
+
+ if (err == NGX_ECONNABORTED) {
+ level = NGX_LOG_ERR;
+
+ } else if (err == NGX_EMFILE || err == NGX_ENFILE) {
+ level = NGX_LOG_CRIT;
+ }
+
#if (NGX_HAVE_ACCEPT4)
- ngx_log_error((ngx_uint_t) ((err == NGX_ECONNABORTED) ?
- NGX_LOG_ERR : NGX_LOG_ALERT),
- ev->log, err,
+ ngx_log_error(level, ev->log, err,
use_accept4 ? "accept4() failed" : "accept() failed");

if (use_accept4 && err == NGX_ENOSYS) {
@@ -82,9 +98,7 @@
continue;
}
#else
- ngx_log_error((ngx_uint_t) ((err == NGX_ECONNABORTED) ?
- NGX_LOG_ERR : NGX_LOG_ALERT),
- ev->log, err, "accept() failed");
+ ngx_log_error(level, ev->log, err, "accept() failed");
#endif

if (err == NGX_ECONNABORTED) {
@@ -97,6 +111,26 @@
}
}

+ if (err == NGX_EMFILE || err == NGX_ENFILE) {
+ if (ngx_disable_accept_events((ngx_cycle_t *) ngx_cycle)
+ != NGX_OK)
+ {
+ return;
+ }
+
+ if (ngx_use_accept_mutex) {
+ if (ngx_accept_mutex_held) {
+ ngx_shmtx_unlock(&ngx_accept_mutex);
+ ngx_accept_mutex_held = 0;
+ }
+
+ ngx_accept_disabled = 1;
+
+ } else {
+ ngx_add_timer(ev, ecf->accept_mutex_delay);
+ }
+ }
+
return;
}

@@ -383,6 +417,10 @@

c = ls[i].connection;

+ if (c->read->active) {
+ continue;
+ }
+
if (ngx_event_flags & NGX_USE_RTSIG_EVENT) {

if (ngx_add_conn(c) == NGX_ERROR) {

Modified: trunk/src/os/unix/ngx_errno.h
===================================================================
--- trunk/src/os/unix/ngx_errno.h 2012-05-11 13:19:22 UTC (rev 4618)
+++ trunk/src/os/unix/ngx_errno.h 2012-05-11 13:33:06 UTC (rev 4619)
@@ -29,6 +29,8 @@
#define NGX_ENOTDIR ENOTDIR
#define NGX_EISDIR EISDIR
#define NGX_EINVAL EINVAL
+#define NGX_ENFILE ENFILE
+#define NGX_EMFILE EMFILE
#define NGX_ENOSPC ENOSPC
#define NGX_EPIPE EPIPE
#define NGX_EINPROGRESS EINPROGRESS

Modified: trunk/src/os/win32/ngx_errno.h
===================================================================
--- trunk/src/os/win32/ngx_errno.h 2012-05-11 13:19:22 UTC (rev 4618)
+++ trunk/src/os/win32/ngx_errno.h 2012-05-11 13:33:06 UTC (rev 4619)
@@ -54,6 +54,8 @@

#define NGX_EALREADY WSAEALREADY
#define NGX_EINVAL WSAEINVAL
+#define NGX_EMFILE WSAEMFILE
+#define NGX_ENFILE WSAEMFILE


u_char *ngx_strerror(ngx_err_t err, u_char *errstr, size_t size);

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