Author: mdounin
Date: 2012-06-18 14:23:42 +0000 (Mon, 18 Jun 2012)
New Revision: 4695
URL: http://trac.nginx.org/nginx/changeset/4695/nginx

Log:
Upstream keepalive: "single" parameter deprecated.

The original idea was to optimize edge cases in case of interchangeable
backends, i.e. don't establish a new connection if we have any one
cached. This causes more harm than good though, as it screws up
underlying balancer's idea about backends used and may result in
various unexpected problems.


Modified:
trunk/src/http/modules/ngx_http_upstream_keepalive_module.c

Modified: trunk/src/http/modules/ngx_http_upstream_keepalive_module.c
===================================================================
--- trunk/src/http/modules/ngx_http_upstream_keepalive_module.c 2012-06-18 14:12:03 UTC (rev 4694)
+++ trunk/src/http/modules/ngx_http_upstream_keepalive_module.c 2012-06-18 14:23:42 UTC (rev 4695)
@@ -12,7 +12,6 @@

typedef struct {
ngx_uint_t max_cached;
- ngx_uint_t single; /* unsigned:1 */

ngx_queue_t cache;
ngx_queue_t free;
@@ -223,36 +222,11 @@

kp->failed = 0;

- /* single pool of cached connections */
+ /* ask balancer */

- if (kp->conf->single && !ngx_queue_empty(&kp->conf->cache)) {
-
- q = ngx_queue_head(&kp->conf->cache);
-
- item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);
- c = item->connection;
-
- ngx_queue_remove(q);
- ngx_queue_insert_head(&kp->conf->free, q);
-
- ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
- "get keepalive peer: using connection %p", c);
-
- c->idle = 0;
- c->log = pc->log;
- c->read->log = pc->log;
- c->write->log = pc->log;
- c->pool->log = pc->log;
-
- pc->connection = c;
- pc->cached = 1;
-
- return NGX_DONE;
- }
-
rc = kp->original_get_peer(pc, kp->data);

- if (kp->conf->single || rc != NGX_OK) {
+ if (rc != NGX_OK) {
return rc;
}

@@ -552,7 +526,8 @@
for (i = 2; i < cf->args->nelts; i++) {

if (ngx_strcmp(value[i].data, "single") == 0) {
- kcf->single = 1;
+ ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
+ "the \"single\" parameter is deprecated");
continue;
}


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