PHP memory_reset_peak_usage() Function: Usage and Examples

Resets peak memory measurement so later memory_get_peak_usage() tracks a specific phase.

What It Does and When to Use It

Measure a phase with a fresh peak baseline. Current allocations answer how much PHP holds now; peak allocations expose workload spikes that can exceed the process limit.

Requirements, Inputs and Expected Behavior

Confirm the runtime, extension, environment variables, and permissions before running the examples in production. Available since PHP 8.2; reset does not decrease actual current memory use.

Example 1: Basic Operation

Measure a phase with a fresh peak baseline.

<?php
memory_reset_peak_usage();
 $payload = range(1, 5_000);
 echo memory_get_peak_usage(true);
 unset($payload);

Example 2: Behavior and Validation

Track a second phase without the first phase peak.

<?php
$first = str_repeat('x', 1_000_000);
 unset($first);
 memory_reset_peak_usage();
 $second = str_repeat('y', 400_000);
 echo memory_get_peak_usage(false);

Practical Example: Application Use

Wrap a deterministic task in a per-phase memory measurement.

<?php
function measured(callable $task): int {
     memory_reset_peak_usage();
     $task();
     return memory_get_peak_usage(true);
 }
 echo measured(static function (): void { $items = range(1, 2000); });

Important Behavior and Edge Cases

The second example highlights: Track a second phase without the first phase peak. The practical example adds: Wrap a deterministic task in a per-phase memory measurement.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Resets peak memory measurement so later memory_get_peak_usage() tracks a specific phase.
• Wrap a deterministic task in a per-phase memory measurement.
• Measure the representative workload before changing memory_limit or forcing garbage collection.