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hrtime

(PHP 7 >= 7.3.0)

hrtimeGet the system's high resolution time

Description

mixed hrtime ([ bool $get_as_number = FALSE ] )

Returns the system's high resolution time, counted from an arbitrary point in time. The delivered timestamp is monotonic and can not be adjusted.

Parameters

get_as_number

Whether the high resolution time should be returned as array or number.

Return Values

Returns an array of integers in the form [seconds, nanoseconds], if the parameter get_as_number is false. Otherwise the nanoseconds are returned as integer (64bit platforms) or float (32bit platforms).

Examples

Example #1 hrtime() usage

<?php
echo hrtime(true), PHP_EOL;
print_r(hrtime());
?>

The above example will output something similar to:

10444739687370679
Array
(
    [0] => 10444739
    [1] => 687464812
)

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User Contributed Notes 1 note

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1
SenseiSimple
1 month ago
This function is particularly necessary on VMs running on KVM, XEN (openstack, AWS EC2, etc) when timing execution times.

On these platforms which lack vDSO the common method of using time() or microtime() can dramatically increase CPU/execution time due to the context switching from userland to kernel when running the `gettimeofday()` system call.

The common pattern is:
<?php
$time
= -microtime(true);
sleep(5);
$end = sprintf('%f', $time += microtime(true));
?>

Substituted as:
<?php
$start
=hrtime(true);
sleep(5);
$end=hrtime(true);
$eta=$end-$start;

echo
$eta/1e+6; //nanoseconds to milliseconds
//5000.362419

//OR simply

$eta=-hrtime(true);
sleep(5);
$eta+=hrtime(true);

echo
$eta/1e+6; //nanoseconds to milliseconds
//5000.088229
?>

There is also the new StopWatch class http://php.net/manual/en/class.hrtime-stopwatch.php
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