Bug #70130 [Fbk->Asn]: usleep(1) CPU usage

Edit report at https://bugs.php.net/bug.php?id=70130&edit=1 ID: 70130 User updated by: saniafd93 at gmail dot com Reported by: saniafd93 at gmail dot com Summary: usleep(1) CPU usage -Status: Feedback +Status: Assigned Type: Bug Package: SPL related Operating System: Ubuntu 14.04 PHP Version: 5.5.27 Assigned To: cmb Block user comment: N Private report: N New Comment: I didn't update to a new version, because the latest PHP version on production environment (Ubuntu 14.04) was PHP 5.5.19 all the time. I was badly surprised by this bug in a LTS version. Anyway, this is a strange behavior, because as I wrote, untill March all worked fine. CPU usage on production Ubuntu 14.04 was ~1% with usleep(1); Same behavior now requires at least usleep(10000); Previous Comments: ------------------------------------------------------------------------ [2015-07-28 23:46:34] cmb@php.net > All worked nice untill March 2015, [...] What do you mean by that? Did you update to a newer PHP version? If so, which version did you use before, and which version do you use now. ------------------------------------------------------------------------ [2015-07-24 17:11:09] saniafd93 at gmail dot com I was wrong about number of cores. Here is new summary with processor models: - 2core Windows 8.1 (Intel Pentium P6100 2.0 GHz) usleep(1); // CPU usage: 0%-1.5% usleep(10000); // CPU usage: 0%-1% - 4core Windows 8.1 (Intel Core i3 4130 3.4 GHz) usleep(1); // CPU usage: 0%-1% usleep(10000); // CPU usage: 0%-1% - 4core Ubuntu 14.04 (Intel Celeron J1900 2.0-2.42GHz) usleep(1); // CPU usage: ~25% usleep(10000); // CPU usage: ~5% - 8core Ubuntu 14.04 (Intel Xeon E5506 2.13GHz) usleep(1); // CPU usage: ~48% usleep(10000); // CPU usage: ~1% ------------------------------------------------------------------------ [2015-07-24 16:37:25] saniafd93 at gmail dot com 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 this bug report at https://bugs.php.net/bug.php?id=70130&edit=1