PHP 中 sleep() 和 usleep() 的区别
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Difference among sleep() and usleep() in PHP
提问by MaxEcho
Can any body explain me what is the difference among sleep()and usleep()in PHP.
任何机构都可以向我解释PHPsleep()和usleep()PHP之间的区别。
I have directed to use following scripts to do chat application for long pulling but in this script I am getting same effect using usleep(25000);or without usleep(25000);
我已指示使用以下脚本来进行长时间拉动的聊天应用程序，但在此脚本中，usleep(25000);无论是否使用，我都获得了相同的效果usleep(25000);
page1.php
页面1.php
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"
type="text/javascript"></script>
<script>
var lpOnComplete = function(response) {
console.log(response);
// do more processing
lpStart();
};
var lpStart = function() {
$.post('page2.php', {}, lpOnComplete, 'json');
};
$(document).ready(lpStart);
</script>
page2.php
页面2.php
<?php
$time = time();
while((time() - $time) < 30) {
// query memcache, database, etc. for new data
$data = getLatest();
// if we have new data return it
if(!empty($data)) {
echo json_encode($data);
break;
}
usleep(25000);
}
function getLatest() {
sleep(2);
return "Test Data";
}
?>
回答by Barmar
The argument to sleepis seconds, the argument to usleepis microseconds. Other than that, I think they're identical.
的参数sleep是秒，参数usleep是微秒。除此之外，我认为它们是相同的。
sleep($n) == usleep($n * 1000000)
usleep(25000)only sleeps for 0.025 seconds.
usleep(25000)只休眠 0.025 秒。
回答by Ashwin
sleep()allows your code to sleep in seconds.
sleep()允许您的代码在几秒钟内休眠。
sleep(5); // sleeps for 5 seconds
sleep(5); // sleeps for 5 seconds
usleep()allows your code with respect to microseconds.
usleep()允许您的代码相对于微秒。
usleep(2500000); // sleeps for 2.5 seconds
usleep(2500000); // sleeps for 2.5 seconds
回答by shahpranaf
usleep()is used to delay execution in "microseconds" while sleep()is used to delay execution in seconds.
So usleep(25000)is 0.025 seconds.
usleep()用于以“微秒”sleep()为单位延迟执行，而用于以秒为单位延迟执行。usleep(25000)0.025 秒也是如此。
Is there any difference between the two?
回答by qualia
One other difference is sleep returns 0 on success, false on error. usleep doesn't return anything.
另一个区别是 sleep 成功时返回 0，错误时返回 false。usleep 不返回任何东西。
回答by Matee Gojra
Simply
简单地
usleepusesCPU Cycleswhilesleepdoes not.
usleep使用CPU Cycles而sleep没有。
sleeptakes secondsas argument
sleep需要seconds作为参数
while usleeptakes microsecondsas argument
同时usleep需要microseconds作为参数
