Upstream hash: limited number of tries in consistent case.
While this may result in non-ideal distribution of requests if nginx
won't be able to select a server in a reasonable number of attempts,
this still looks better than severe performance degradation observed
if there is no limit and there are many points configured (ticket #1030).
This is also in line with what we do for other hash balancing methods.
diff --git a/src/http/modules/ngx_http_upstream_hash_module.c b/src/http/modules/ngx_http_upstream_hash_module.c
index 6c28c64..78e672c 100644
--- a/src/http/modules/ngx_http_upstream_hash_module.c
+++ b/src/http/modules/ngx_http_upstream_hash_module.c
@@ -503,6 +503,11 @@
ngx_http_upstream_rr_peers_wlock(hp->rrp.peers);
+ if (hp->tries > 20 || hp->rrp.peers->single) {
+ ngx_http_upstream_rr_peers_unlock(hp->rrp.peers);
+ return hp->get_rr_peer(pc, &hp->rrp);
+ }
+
pc->cached = 0;
pc->connection = NULL;
@@ -577,10 +582,9 @@
hp->hash++;
hp->tries++;
- if (hp->tries >= points->number) {
- pc->name = hp->rrp.peers->name;
+ if (hp->tries > 20) {
ngx_http_upstream_rr_peers_unlock(hp->rrp.peers);
- return NGX_BUSY;
+ return hp->get_rr_peer(pc, &hp->rrp);
}
}
diff --git a/src/stream/ngx_stream_upstream_hash_module.c b/src/stream/ngx_stream_upstream_hash_module.c
index cb44fcd..4135379 100644
--- a/src/stream/ngx_stream_upstream_hash_module.c
+++ b/src/stream/ngx_stream_upstream_hash_module.c
@@ -505,6 +505,11 @@
ngx_stream_upstream_rr_peers_wlock(hp->rrp.peers);
+ if (hp->tries > 20 || hp->rrp.peers->single) {
+ ngx_stream_upstream_rr_peers_unlock(hp->rrp.peers);
+ return hp->get_rr_peer(pc, &hp->rrp);
+ }
+
pc->connection = NULL;
now = ngx_time();
@@ -578,10 +583,9 @@
hp->hash++;
hp->tries++;
- if (hp->tries >= points->number) {
- pc->name = hp->rrp.peers->name;
+ if (hp->tries > 20) {
ngx_stream_upstream_rr_peers_unlock(hp->rrp.peers);
- return NGX_BUSY;
+ return hp->get_rr_peer(pc, &hp->rrp);
}
}