diff --git a/src/http/modules/ngx_http_upstream_hash_module.c b/src/http/modules/ngx_http_upstream_hash_module.c
index 777e180..b6b7830 100644
--- a/src/http/modules/ngx_http_upstream_hash_module.c
+++ b/src/http/modules/ngx_http_upstream_hash_module.c
@@ -9,6 +9,9 @@
 #include <ngx_core.h>
 #include <ngx_http.h>
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+#include "ngx_http_upstream_check_module.h"
+#endif
 
 typedef struct {
     uint32_t                            hash;
@@ -240,6 +243,15 @@ ngx_http_upstream_get_hash_peer(ngx_peer_connection_t *pc, void *data)
             goto next;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+            "get hash peer, check_index: %ui",
+             peer->check_index);
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            goto next;
+        }
+#endif
+
         if (peer->max_fails
             && peer->fails >= peer->max_fails
             && now - peer->checked <= peer->fail_timeout)
@@ -506,6 +518,15 @@ ngx_http_upstream_get_chash_peer(ngx_peer_connection_t *pc, void *data)
                 continue;
             }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+            "get consistent_hash peer, check_index: %ui",
+             peer->check_index);
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            continue;
+        }
+#endif
+
             if (peer->server.len != server->len
                 || ngx_strncmp(peer->server.data, server->data, server->len)
                    != 0)
diff --git a/src/http/modules/ngx_http_upstream_ip_hash_module.c b/src/http/modules/ngx_http_upstream_ip_hash_module.c
index 148d73a..913e395 100644
--- a/src/http/modules/ngx_http_upstream_ip_hash_module.c
+++ b/src/http/modules/ngx_http_upstream_ip_hash_module.c
@@ -9,6 +9,9 @@
 #include <ngx_core.h>
 #include <ngx_http.h>
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+#include "ngx_http_upstream_check_module.h"
+#endif
 
 typedef struct {
     /* the round robin data must be first */
@@ -212,6 +215,15 @@ ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
             goto next_try;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+            "get ip_hash peer, check_index: %ui",
+             peer->check_index);
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            goto next_try;
+        }
+#endif
+
         if (peer->max_fails
             && peer->fails >= peer->max_fails
             && now - peer->checked <= peer->fail_timeout)
diff --git a/src/http/modules/ngx_http_upstream_least_conn_module.c b/src/http/modules/ngx_http_upstream_least_conn_module.c
index 623bc9b..a223839 100644
--- a/src/http/modules/ngx_http_upstream_least_conn_module.c
+++ b/src/http/modules/ngx_http_upstream_least_conn_module.c
@@ -9,6 +9,9 @@
 #include <ngx_core.h>
 #include <ngx_http.h>
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+#include "ngx_http_upstream_check_module.h"
+#endif
 
 typedef struct {
     ngx_uint_t                        *conns;
@@ -203,6 +206,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
             continue;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+                "get least_conn peer, check_index: %ui",
+                peer->check_index);
+
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            continue;
+        }
+#endif
+
         if (peer->max_fails
             && peer->fails >= peer->max_fails
             && now - peer->checked <= peer->fail_timeout)
@@ -256,6 +269,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
                 continue;
             }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
+                    "get least_conn peer, check_index: %ui",
+                    peer->check_index);
+
+            if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+                continue;
+            }
+#endif
+
             if (lcp->conns[i] * best->weight != lcp->conns[p] * peer->weight) {
                 continue;
             }
diff --git a/src/http/ngx_http_upstream_round_robin.c b/src/http/ngx_http_upstream_round_robin.c
index 2d0649b..b9789eb 100644
--- a/src/http/ngx_http_upstream_round_robin.c
+++ b/src/http/ngx_http_upstream_round_robin.c
@@ -9,6 +9,9 @@
 #include <ngx_core.h>
 #include <ngx_http.h>
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+#include "ngx_http_upstream_check_module.h"
+#endif
 
 #define ngx_http_upstream_tries(p) ((p)->number                               \
                                     + ((p)->next ? (p)->next->number : 0))
@@ -92,6 +95,14 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
                 peer[n].fail_timeout = server[i].fail_timeout;
                 peer[n].down = server[i].down;
                 peer[n].server = server[i].name;
+#if (NGX_HTTP_UPSTREAM_CHECK)
+                if (!server[i].down) {
+                    peers->peer[n].check_index =
+                        ngx_http_upstream_check_add_peer(cf, us, &server[i].addrs[j]);
+                } else {
+                    peers->peer[n].check_index = (ngx_uint_t) NGX_ERROR;
+                }
+#endif
                 n++;
             }
         }
@@ -148,6 +159,15 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
                 peer[n].fail_timeout = server[i].fail_timeout;
                 peer[n].down = server[i].down;
                 peer[n].server = server[i].name;
+#if (NGX_HTTP_UPSTREAM_CHECK)
+                if (!server[i].down) {
+                    backup->peer[n].check_index =
+                        ngx_http_upstream_check_add_peer(cf, us, &server[i].addrs[j]);
+                }
+                else {
+                    backup->peer[n].check_index = (ngx_uint_t) NGX_ERROR;
+                }
+#endif
                 n++;
             }
         }
@@ -207,6 +227,9 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
         peer[i].current_weight = 0;
         peer[i].max_fails = 1;
         peer[i].fail_timeout = 10;
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        peers->peer[i].check_index = (ngx_uint_t) NGX_ERROR;
+#endif
     }
 
     us->peer.data = peers;
@@ -316,7 +339,9 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
         peer[0].current_weight = 0;
         peer[0].max_fails = 1;
         peer[0].fail_timeout = 10;
-
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        peers->peer[0].check_index = (ngx_uint_t) NGX_ERROR;
+#endif
     } else {
 
         for (i = 0; i < ur->naddrs; i++) {
@@ -356,6 +381,9 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
             peer[i].current_weight = 0;
             peer[i].max_fails = 1;
             peer[i].fail_timeout = 10;
+#if (NGX_HTTP_UPSTREAM_CHECK)
+            peers->peer[i].check_index = (ngx_uint_t) NGX_ERROR;
+#endif
         }
     }
 
@@ -415,6 +443,12 @@ ngx_http_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data)
             goto failed;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            goto failed;
+        }
+#endif
+
     } else {
 
         /* there are several peers */
@@ -507,6 +541,12 @@ ngx_http_upstream_get_peer(ngx_http_upstream_rr_peer_data_t *rrp)
             continue;
         }
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
+            continue;
+        }
+#endif
+
         if (peer->max_fails
             && peer->fails >= peer->max_fails
             && now - peer->checked <= peer->fail_timeout)
diff --git a/src/http/ngx_http_upstream_round_robin.h b/src/http/ngx_http_upstream_round_robin.h
index 9db82a6..6e19a65 100644
--- a/src/http/ngx_http_upstream_round_robin.h
+++ b/src/http/ngx_http_upstream_round_robin.h
@@ -31,6 +31,10 @@ typedef struct {
     ngx_uint_t                      max_fails;
     time_t                          fail_timeout;
 
+#if (NGX_HTTP_UPSTREAM_CHECK)
+    ngx_uint_t                      check_index;
+#endif
+
     ngx_uint_t                      down;          /* unsigned  down:1; */
 
 #if (NGX_HTTP_SSL)