English
English
The opendir() and readdir() functions allocate system resources to open and read directories. When multiple directories are opened or these functions are called frequently, failing to call closedir() can cause unreleased resources to accumulate during program execution. This not only consumes system memory but may also lead to memory leaks, which can affect the program’s performance and stability.
In PHP, file handles are a limited system resource. If you forget to call closedir(), the directory resources opened by each opendir() call will not be released. This results in a growing number of file handles, which may eventually exhaust the available handles, preventing opendir() or other file operations from functioning properly. This issue is especially problematic when handling large numbers of files or directories, as running out of file handles will stop the program from executing related file operations.
When a PHP program does not close directory resources in time, unreleased resources consume CPU and memory, reducing execution efficiency. This is particularly harmful for long-running scripts (such as daemons or background tasks), where unclosed directory handles continuously drain system resources, leading to overall performance degradation. In high-concurrency scenarios, excessive resource usage can slow down the entire system’s response speed.
If directory resources are not closed properly, the system’s file handle limits may be exhausted prematurely, preventing the operating system from allocating new handles. This affects not only PHP programs but also other processes running on the system, potentially causing abnormal file system operations across the board.
If you forget to use closedir(), in some cases the program may not throw obvious errors or warnings, making it difficult for developers to realize that resources haven’t been released. Since closedir() is not a mandatory function, many developers might overlook it after writing their code, causing resource leaks to surface gradually in production environments. Debugging these kinds of problems often requires deeper investigation, which increases development and maintenance complexity.
