Bug #70130 [NEW]: usleep(1) CPU usage

From: Date: Fri, 24 Jul 2015 16:37:25 +0000
Subject: Bug #70130 [NEW]: usleep(1) CPU usage
Groups: php.bugs 
Request: Send a blank email to php-bugs+get-194685@lists.php.net to get a copy of this message 
From:             saniafd93 at gmail dot com
Operating system: Ubuntu 14.04
PHP version:      5.5.27
Package:          SPL related
Bug Type:         Bug
Bug description:usleep(1) CPU usage

Description:
------------
*PHP version 5.5.19

Short time ago I wrote an app, that uses usleep(1) for reducing CPU
usage. I wrote it on my Windows 8.1 machine, and it's worked as
suspected: CPU usage was reduced to 0%-1%. After that, I runned it on
Ubuntu 14.04, and there was same behavior: 0%-1.5% CPU usage.

All worked nice untill March 2015, when on Ubuntu CPU usage was
increased up to 48% (2-core server). I tested that app again, and found
that on Windows CPU usage was still 0%-1%.

I tested it in several environments: 2core Windows 8.1, 4core Windows
8.1, 2core Ubuntu 14.04, 4core Ubuntu 14.04.

Test script:
---------------
<?php
// usage below is right for Ubuntu 14.04 machines
// Windows 8.1 machines all the time have 0%-1.5%

while (true) {
	usleep(1);     // CPU usage: ~48% 2core machine, ~25% 4core machine
	usleep(10000); // CPU usage:  ~5% 2core machine,  ~1% 4core machine
}


-- 
Edit bug report at https://bugs.php.net/bug.php?id=70130&edit=1
-- 
Try a snapshot (PHP 5.4):   https://bugs.php.net/fix.php?id=70130&r=trysnapshot54
Try a snapshot (PHP 5.5):   https://bugs.php.net/fix.php?id=70130&r=trysnapshot55
Try a snapshot (trunk):     https://bugs.php.net/fix.php?id=70130&r=trysnapshottrunk
Fixed in SVN:               https://bugs.php.net/fix.php?id=70130&r=fixed
Fixed in release:           https://bugs.php.net/fix.php?id=70130&r=alreadyfixed
Need backtrace:             https://bugs.php.net/fix.php?id=70130&r=needtrace
Need Reproduce Script:      https://bugs.php.net/fix.php?id=70130&r=needscript
Try newer version:          https://bugs.php.net/fix.php?id=70130&r=oldversion
Not developer issue:        https://bugs.php.net/fix.php?id=70130&r=support
Expected behavior:          https://bugs.php.net/fix.php?id=70130&r=notwrong
Not enough info:            https://bugs.php.net/fix.php?id=70130&r=notenoughinfo
Submitted twice:            https://bugs.php.net/fix.php?id=70130&r=submittedtwice
register_globals:           https://bugs.php.net/fix.php?id=70130&r=globals
PHP 4 support discontinued: https://bugs.php.net/fix.php?id=70130&r=php4
Daylight Savings:           https://bugs.php.net/fix.php?id=70130&r=dst
IIS Stability:              https://bugs.php.net/fix.php?id=70130&r=isapi
Install GNU Sed:            https://bugs.php.net/fix.php?id=70130&r=gnused
Floating point limitations: https://bugs.php.net/fix.php?id=70130&r=float
No Zend Extensions:         https://bugs.php.net/fix.php?id=70130&r=nozend
MySQL Configuration Error:  https://bugs.php.net/fix.php?id=70130&r=mysqlcfg

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