Cannot load modules/mod_proxy_wstunnel.so into server

Recently I need integrate a websocket server with apache2，and I find that apache2.4 has supported websocket with the module : mod_proxy_wstunnel. http://httpd.apache.org/docs/2.4/mod/mod_proxy_wstunnel.html

I compiled them by myself, but encountered a problem :

httpd: Syntax error on line 122 of /usr/local/apache2/conf/httpd.conf: Cannot load modules/mod_proxy_wstunnel.so into server: /usr/local/apache2/modules/mod_proxy_wstunnel.so: undefined symbol: ap_proxy_release_connection

• environment info:
• OS:centos 6.8
• php:php-7.0.10
• apache:httpd-2.4.23

My steps are:

1. Download source code.
   • php7 github.com/php/php-src/releases/tag/php-7.0.10
   • apache2.4 github.com/apache/httpd/releases/tag/2.4.23
     
2. Copy to my workspace and tar，say /home
   • shell> tar -xjf php-7.0.10.tar.bz2
   • shell> tar -xjf httpd-2.4.23.tar.bz2
3. Install gcc : yum install gcc
4. Compile apache
   • down apr：apr-1.5.2.tar.gz apr-util-1.5.4.tar.gz
   • copy to /httpd-2.4.23/srclib
tar -zvf apr-1.5.2.tar.gz tar -zvf apr-util-1.5.4.tar.gz
   • Modify the files name:
     apr-1.5.2 as apr
apr-util-1.5.4 as apr-util
     
   • Install pcre
     yum install pcre-devel
     
   • ./configure --enable-so --enable-http --enable-proxy --enable-proxy-http --with-included-apr --enable-proxy-wstunnel
   • make && make install
   • set apache server ip：
     shell> vi /usr/local/apache2/conf/httpd.conf ServerName 127.0.0.1
5. Compile php
   • libxml2:
     yum install libxml2-devel
   • mkdir /usr/local/php7
   • ./configure --prefix=/usr/local/php7 --with-mysqli --enable-mysqlnd --with-mysql-sock=/var/lib/mysql/mysql.sock --with-apxs2=/usr/local/apache2/bin/apxs
   • make && make install
   • cp -v ./php.ini-production /usr/local/php7/lib/php.ini
   • configure httpd.conf
     shell> vi /usr/local/apache2/conf/httpd.conf
     <FilesMatch \.php$> SetHandler application/x-httpd-php </FilesMatch>
6. enalbe mod_proxy_wstunnel shell> vi /usr/local/apache2/conf/httpd.conf
   LoadModule proxy_wstunnel_module modules/mod_proxy_wstunnel.so

Above is my steps. Then I try to start my apache2 :

/usr/local/apache2/bin/apachectl start

Got the following errors:

httpd: Syntax error on line 122 of /usr/local/apache2/conf/httpd.conf: Cannot load modules/mod_proxy_wstunnel.so into server: /usr/local/apache2/modules/mod_proxy_wstunnel.so: undefined symbol: ap_proxy_release_connection

I have google it , but can't find some helpful info.