After turning on opcache, WordPress becomes completely unresponsive?

After using WordPress for a while, I developed a theme. After installing several plug-ins, the website performance dropped, so I planned to turn on opcache, but after turning it on, the website became completely unresponsive (no response immediately after making a request) ), the apache server did not record any error logs.
Server software versions: centos, php5.4, wordpress4.5, apache2.2
Web server operating environment: apache uses the modfcgi module to run php
Tried methods:

<code>在没有完全重装wp的情况下，停用或删除所有插件，使用wp自带的主题，删除整个数据库，重新安装wp数据库，更新wp到最新版本。都无效果。
完全重装（即是重新下载安装包安装）后，就没问题。所以这也可以得出此问题跟操作系统和apache应该是无关的。
</code>

The following is a screenshot of the response when chrome accesses the problematic wp:

The configuration of opcache in php.ini is as follows (I originally wanted to send the entire ini file, but it exceeded the allowed length of the article):

<code>zend_extension="/usr/local/php/lib/php/extensions/no-debug-non-zts-20100525/opcache.so"
;opcache.blacklist_filename="/etc/php/opcache/blacklists"
opcache.memory_consumption=256
opcache.interned_strings_buffer=16
</code>

Reply content:

After using WordPress for a while, I developed a theme. After installing several plug-ins, the website performance dropped, so I planned to turn on opcache, but after turning it on, the website became completely unresponsive (no response immediately after making a request) ), the apache server did not record any error logs.
Server software versions: centos, php5.4, wordpress4.5, apache2.2
Web server operating environment: apache uses the modfcgi module to run php
Tried methods:

<code>在没有完全重装wp的情况下，停用或删除所有插件，使用wp自带的主题，删除整个数据库，重新安装wp数据库，更新wp到最新版本。都无效果。
完全重装（即是重新下载安装包安装）后，就没问题。所以这也可以得出此问题跟操作系统和apache应该是无关的。
</code>

The following is a screenshot of the response when chrome accesses the problematic wp:

The configuration of opcache in php.ini is as follows (I originally wanted to send the entire ini file, but it exceeded the allowed length of the article):

<code>zend_extension="/usr/local/php/lib/php/extensions/no-debug-non-zts-20100525/opcache.so"
;opcache.blacklist_filename="/etc/php/opcache/blacklists"
opcache.memory_consumption=256
opcache.interned_strings_buffer=16
</code>

The cause of the problem has been found. It is not the fault of wp, but because the two PHP code encryption extensions zend guard and ioncube are enabled in php.ini.