What Does the Data Structure Returned by the opcache_get_status Function Consist Of? How to Interpret Each Field?

gitbox 2025-08-22

What Does the Data Structure Returned by the opcache_get_status Function Consist Of? How to Interpret Each Field?

In PHP, OPcache is a caching system that accelerates script execution by storing precompiled bytecode in memory. The opcache_get_status function is a highly useful debugging tool that retrieves the current status of OPcache. With it, you can monitor cache utilization, hit rates, and other performance indicators.

1. Introduction to the opcache_get_status Function

The basic syntax of the opcache_get_status function is as follows:

<span><span><span class="hljs-keyword">array</span></span><span> </span><span><span class="hljs-title function_ invoke__">opcache_get_status</span></span><span> ( </span><span><span class="hljs-keyword">bool</span></span><span> </span><span><span class="hljs-variable">$no_cache</span></span><span> = </span><span><span class="hljs-literal">false</span></span><span> )
</span></span>

The parameter $no_cache determines whether to bypass the cache when fetching data. By default, it is set to false, meaning it retrieves information from the cache. If set to true, the function fetches data directly from OPcache, ignoring the cached content.

The function returns an associative array containing OPcache status information. Below, we’ll break down the meaning of each field.

2. Data Structure Returned by opcache_get_status

The array returned by opcache_get_status consists of two main sections: opcache and scripts. The specific fields are explained below:

2.1 The opcache Section

This section contains global statistics about OPcache. Key fields include:

version: The current OPcache version.

Example: "7.4.3", "8.0.0"

This field indicates the version of OPcache in use, which helps determine whether an update may be required.

memory_usage: Memory usage statistics, with the following subfields:

used_memory: The amount of memory currently used by OPcache (in bytes).
free_memory: The amount of available memory in OPcache (in bytes).
wasted_memory: The amount of wasted memory, usually caused by invalid data or fragmentation in the cache.
current_wasted_percentage: The percentage of wasted memory relative to total memory.

Example:

<span><span><span class="hljs-string">"memory_usage"</span></span><span> =&gt; </span><span><span class="hljs-keyword">array</span></span><span>(
    </span><span><span class="hljs-string">"used_memory"</span></span><span> =&gt; </span><span><span class="hljs-number">12345678</span></span><span>,
    </span><span><span class="hljs-string">"free_memory"</span></span><span> =&gt; </span><span><span class="hljs-number">8765432</span></span><span>,
    </span><span><span class="hljs-string">"wasted_memory"</span></span><span> =&gt; </span><span><span class="hljs-number">123456</span></span><span>,
    </span><span><span class="hljs-string">"current_wasted_percentage"</span></span><span> =&gt; </span><span><span class="hljs-number">1.2</span></span><span>
)
</span></span>

opcache_hit_rate: The OPcache hit rate, expressed as a percentage, showing how often scripts are served from the cache.

Example: 98.4%

This is a critical metric to evaluate cache effectiveness—the higher the value, the better the performance.
cache_full: A boolean indicating whether the OPcache cache is full. true means the cache is full; false means it is not.

Example: true or false
restart_pending: A boolean indicating whether an OPcache restart is scheduled. true means a restart is pending, false means no restart is needed.
restart_in_progress: A boolean showing whether OPcache is currently being restarted. If true, a restart is in progress.

2.2 The scripts Section

This section contains the status of all scripts currently cached, including:

filename: The file path of the script.
Example: "/var/www/html/index.php"
opcache_hits: The number of times the script has been served from the cache.
memory_consumption: The amount of memory consumed by the script within OPcache.
last_used: The timestamp of the script’s last usage.
timestamp: The timestamp when the script was first cached.
user: User information for the script, typically the username under which it was executed.

2.3 Other Fields

In addition to the common fields above, the array returned by opcache_get_status may include specific debugging or configuration details depending on the PHP version and OPcache settings.

3. How to Interpret These Fields

Understanding these fields helps monitor and optimize OPcache usage. Here’s how to interpret them:

Memory Usage: The used_memory and free_memory fields show memory consumption and availability. If used_memory is high and free_memory is low, it may indicate the need to increase OPcache memory or clear unused cache. The wasted_memory and current_wasted_percentage values reveal fragmentation issues—if these are high, tweaking cache settings may improve efficiency.
Hit Rate: The opcache_hit_rate is a crucial performance metric. A high hit rate means most scripts are served from cache, leading to faster execution. A low rate may suggest frequent script modifications or suboptimal OPcache settings.
Cache Restarts: The restart_pending and restart_in_progress fields show whether OPcache is in the process of restarting. Frequent restarts may signal misconfigurations and should prompt a review of OPcache settings.
Script Status: The scripts section provides details about each cached script. Reviewing this information can highlight scripts with low hit rates or excessive memory usage, helping developers optimize specific files.

4. Conclusion

By analyzing the data returned by the opcache_get_status function, developers can monitor OPcache in real time and fine-tune PHP script execution. A solid understanding of these fields enables effective OPcache configuration, ultimately improving website responsiveness and overall performance.

opcache_get_status