From: Ruediger Pluem <rpluem@apache.org>
Date: Sat, 9 Aug 2008 21:33:09 +0000 (+0000)
Subject: * Introduce environment variable proxy-initial-not-pooled to avoid reusing
X-Git-Tag: 2.3.0~380
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=0afe61c5bdd79b46039dd0128e8b80340dc6d40b;p=apache

* Introduce environment variable proxy-initial-not-pooled to avoid reusing
  pooled connections if the client connection is an initial connection.
  This avoids the "proxy: error reading status line from remote server"
  error caused by the race condition that the backend server closed the
  connection after the connection check on our side and before our data
  reached the backend. Yes, this downgrades performance, especially with
  HTTP/1.0 clients. Hence it is configurable and off by default.

PR: 37770


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@684351 13f79535-47bb-0310-9956-ffa450edef68
---

diff --git a/CHANGES b/CHANGES
index c78b4e01f2..8764bddc03 100644
--- a/CHANGES
+++ b/CHANGES
@@ -2,6 +2,10 @@
 Changes with Apache 2.3.0
 [ When backported to 2.2.x, remove entry from this file ]
 
+  *) mod_proxy_http: Introduce environment variable proxy-initial-not-pooled to
+     avoid reusing pooled connections if the client connection is an initial
+     connection. PR 37770. [Ruediger Pluem]
+
   *) mod_proxy: Add connectiontimeout parameter for proxy workers in order to
      be able to set the timeout for connecting to the backend separately.
      PR 45445. [Ruediger Pluem, rahul <rahul sun.com>]
diff --git a/modules/proxy/mod_proxy_http.c b/modules/proxy/mod_proxy_http.c
index c7be88ff71..4b99128442 100644
--- a/modules/proxy/mod_proxy_http.c
+++ b/modules/proxy/mod_proxy_http.c
@@ -1927,6 +1927,19 @@ static int proxy_http_handler(request_rec *r, proxy_worker *worker,
         ap_proxy_ssl_connection_cleanup(backend, r);
     }
 
+    /*
+     * In the case that we are handling a reverse proxy connection and this
+     * is not a request that is coming over an already kept alive connection
+     * with the client, do NOT reuse the connection to the backend, because
+     * we cannot forward a failure to the client in this case as the client
+     * does NOT expects this in this situation.
+     * Yes, this creates a performance penalty.
+     */
+    if ((r->proxyreq == PROXYREQ_REVERSE) && (!c->keepalives)
+        && (apr_table_get(r->subprocess_env, "proxy-initial-not-pooled"))) {
+        backend->close = 1;
+    }
+
     /* Step One: Determine Who To Connect To */
     if ((status = ap_proxy_determine_connection(p, r, conf, worker, backend,
                                                 uri, &url, proxyname,
diff --git a/modules/proxy/proxy_util.c b/modules/proxy/proxy_util.c
index 2a55c5bcac..fd46206ebe 100644
--- a/modules/proxy/proxy_util.c
+++ b/modules/proxy/proxy_util.c
@@ -2167,6 +2167,11 @@ ap_proxy_determine_connection(apr_pool_t *p, request_rec *r,
     else {
         conn->addr = worker->cp->addr;
     }
+    /* Close a possible existing socket if we are told to do so */
+    if (conn->close) {
+        socket_cleanup(conn);
+        conn->close = 0;
+    }
 
     if (err != APR_SUCCESS) {
         return ap_proxyerror(r, HTTP_BAD_GATEWAY,