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When using finfo for file type detection, PHP opens a resource stream with finfo_open(). This stream is used to manage internal resources related to file information. finfo_open() works similarly to opening a file handle, while finfo_close() releases the resource and closes the corresponding handle. If finfo_close() is not called, PHP cannot free these resources, leading to leaks.
PHP allocates memory to handle opened file information streams during runtime. If finfo_close() is forgotten, these resources won’t be released in time, causing memory usage to keep increasing. In high-load applications, repeated calls to finfo_open() and finfo_file() can accumulate unreleased resources, potentially exhausting memory and degrading server performance, even causing application crashes.
Each call to finfo_open() consumes a file handle. If finfo_close() is not called, PHP cannot recycle these handles, leading to a growing number of open file handles. Since file handles are limited, too many unreleased handles may prevent other operations—such as opening files or database connections—from working properly, affecting overall system stability.
In multithreaded or high-concurrency environments, forgetting finfo_close() can put extra strain on system resource allocation, causing performance degradation. When multiple requests hit the application simultaneously, resource leaks may block new requests from being processed normally, resulting in slower response times or timeouts, thereby harming user experience.
When a large number of unclosed file information streams consume resources, they may “lock” or “exhaust” resources needed for other operations, leading to resource contention. This competition can prevent other programs or scripts from running smoothly, lowering overall efficiency.
To prevent performance issues caused by forgetting to call finfo_close(), developers can take the following measures:
The most important step is to always call finfo_close() immediately after finishing with finfo-related functions. This is the most direct and effective way to avoid resource leaks. For example:
<span><span><span class="hljs-variable">$finfo</span></span><span> = </span><span><span class="hljs-title function_ invoke__">finfo_open</span></span><span>(FILEINFO_MIME_TYPE); </span><span><span class="hljs-comment">// Open finfo resource</span></span><span>
</span><span><span class="hljs-variable">$mimeType</span></span><span> = </span><span><span class="hljs-title function_ invoke__">finfo_file</span></span><span>(</span><span><span class="hljs-variable">$finfo</span></span><span>, </span><span><span class="hljs-string">'example.txt'</span></span><span>); </span><span><span class="hljs-comment">// Get file MIME type</span></span><span>
</span><span><span class="hljs-title function_ invoke__">finfo_close</span></span><span>(</span><span><span class="hljs-variable">$finfo</span></span><span>); </span><span><span class="hljs-comment">// Close finfo resource</span></span><span>
</span></span>In some cases, developers can rely on PHP’s garbage collection mechanism to ensure that resources are released when no longer in use. For example, you can encapsulate finfo resources in a class and call finfo_close() in the destructor. This ensures the resource is freed even if you forget to explicitly call finfo_close().
<span><span><span class="hljs-class"><span class="hljs-keyword">class</span></span></span><span> </span><span><span class="hljs-title">FileInfoHandler</span></span><span> {
</span><span><span class="hljs-keyword">private</span></span><span> </span><span><span class="hljs-variable">$finfo</span></span><span>;
</span><span><span class="hljs-variable language_">$this</span></span><span>->finfo = </span><span><span class="hljs-title function_ invoke__">finfo_open</span></span><span>(FILEINFO_MIME_TYPE);
}
</span><span><span class="hljs-keyword">public</span></span><span> </span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">getMimeType</span></span><span>(</span><span><span class="hljs-variable">$filePath</span></span><span>) {
</span><span><span class="hljs-keyword">return</span></span> </span><span class="hljs-title function_ invoke__">finfo_file</span></span><span>(</span><span><span class="hljs-variable">$this</span></span>->finfo, </span><span class="hljs-variable">$filePath</span></span><span>);
}
</span><span><span class="hljs-keyword">public</span></span><span> </span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span class="hljs-title">__destruct</span></span><span>() {
</span><span><span class="hljs-title function_ invoke__">finfo_close</span></span>(</span><span class="hljs-variable">$this</span>->finfo); </span><span class="hljs-comment">// Close resource on destruction</span></span><span>
}
}
During code reviews and performance testing—especially in areas with heavy resource usage—regularly check for unclosed file streams or database connections. Static analysis tools and scheduled code quality checks can effectively identify potential issues.
When using finfo or similar functions that require resource management, a try-catch-finally structure ensures resources are always released. Even if an exception occurs, the finally block guarantees that finfo_close() is executed.
<span><span><span class="hljs-keyword">try</span></span><span> {
</span><span><span class="hljs-variable">$finfo</span></span><span> = </span><span><span class="hljs-title function_ invoke__">finfo_open</span></span><span>(FILEINFO_MIME_TYPE);
</span><span><span class="hljs-variable">$mimeType</span></span><span> = </span><span><span class="hljs-title function_ invoke__">finfo_file</span></span>(</span><span class="hljs-variable">$finfo</span>, </span><span class="hljs-string">'example.txt'</span></span><span>);
} </span><span><span class="hljs-keyword">catch</span> (</span><span class="hljs-built_in">Exception</span> </span><span class="hljs-variable">$e</span></span>) {
</span><span><span class="hljs-comment">// Handle exception</span></span><span>
} </span><span><span class="hljs-keyword">finally</span></span><span> {
</span><span><span class="hljs-keyword">if</span> (</span><span class="hljs-variable">$finfo</span></span>) {
</span><span><span class="hljs-title function_ invoke__">finfo_close</span></span>(</span><span class="hljs-variable">$finfo</span></span>); </span><span class="hljs-comment">// Ensure resource is closed</span></span><span>
}
}
</span></span>Forgetting to call finfo_close() may seem like a small mistake, but it can have a major impact on performance and stability. By practicing good resource management, using automatic resource release, regularly checking code for resource usage, and applying proper error-handling mechanisms, developers can effectively prevent these issues and improve the overall efficiency and reliability of PHP applications.
