PHP usleep() pauses execution for a specified number of microseconds. The examples below show how the call behaves, where it is useful, and which limitations matter.
What Is usleep() in PHP?
Pauses execution for a specified number of microseconds.
Its call structure is:
usleep($microseconds)The arguments identify the values or resources passed to usleep(). Read the examples with attention to the type of each supplied argument and to whether the function modifies its input or returns a separate result.
Example 1: Basic Usage
This example introduces usleep with a direct call and a small, readable input.
<?php
usleep(100000); echo "Finished";Pauses execution for a specified number of microseconds. Sleep accuracy depends on the scheduler; this blocks the current PHP worker.
Example 2: Another Behavior or Input
Compare this input with the previous example: changing the data or option can affect how usleep behaves.
<?php
$startedAt = microtime(true); usleep(250000); echo round(microtime(true) - $startedAt, 2);The changed input illustrates why output may differ with the chosen values or environment. Sleep accuracy depends on the scheduler; this blocks the current PHP worker.
Practical Example: Using the Feature
The following example incorporates usleep into a workflow. Values such as paths, connection handles and configuration options must come from trusted application settings.
<?php
for ($attemptNumber = 1; $attemptNumber <= 2; $attemptNumber++) { echo "Retry {$attemptNumber}\n"; if ($attemptNumber < 2) { usleep(200000); } }In a real application, check each operation result, validate values before use and clean up acquired resources. Sleep accuracy depends on the scheduler; this blocks the current PHP worker.
Important Behavior and Edge Cases
- Purpose: Pauses execution for a specified number of microseconds.
- Key limitation: Sleep accuracy depends on the scheduler; this blocks the current PHP worker.
- Failure handling: Check return values and handle invalid inputs and unavailable operating-system or extension features where relevant.
Comparison With Related Functions
| Function or Approach | Best Fit |
|---|---|
usleep() | Pauses execution for a specified number of microseconds. |
sleep() | Blocks for whole seconds rather than a chosen number of microseconds. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Sleep accuracy depends on the scheduler; this blocks the current PHP worker. | The correct approach depends on this behavior: Sleep accuracy depends on the scheduler; this blocks the current PHP worker. |
| Ignoring errors or cleanup after the operation. | Validate inputs and check each result; close files, restore settings or release resources when the operation requires it. |
Key Takeaways
- Pauses execution for a specified number of microseconds.
- Sleep accuracy depends on the scheduler; this blocks the current PHP worker.
- Use the examples as starting points, and adapt environmental paths, resources and permissions rather than assuming fixed results.
usleep is useful when its specific behavior fits the problem. The safest implementations combine the correct API with input validation, error checking and resource cleanup.