Laravel scheduler running with delay (not on time)

Question

Laravel 5.5 PHP 7.1

I have a strange issue on production server that delays the scheduler so tasks are not fired on time. It seems that for some reason the command artisan schedule:run sometimes takes time to load. If I run artisan schedule:run from console, it runs immediately, the issue is when is fired with the cron job. I have set the cron to fire by 5 minutes instead of all minutes to see more clear.

Cron log:

Sep 29 10:05:01 localhost CROND[17311]
Sep 29 10:10:01 localhost CROND[17846]
Sep 29 10:15:01 localhost CROND[18165]

Scheduler log:

Received ping at Saturday, 29-Sep-2018 10:06:11 EDT 
Received ping at Saturday, 29-Sep-2018 10:10:01 EDT 
Received ping at Saturday, 29-Sep-2018 10:18:55 EDT

The only task the scheduler has is a simple closure to measure time, no complex tasks.

$schedule->call(function () {
        return true;
    })
    ->everyMinute()
    ->pingBefore('...')

Somebody told me this could be a server load issue or clock sync, after running uptime; sar -q; etc uptime; sar -q; etc uptime; sar -q; etc the results are 10:52:05 up 4:29, 1 user, load average: 0,02, 0,04, 0,05 and clock is on sync.

The real issue is that if I have a task set to run eg at 10:05, it never runs, because the scheduler is loaded at 10:06.

Any ideas?

Updated results: ----------------

I have discovered that if I execute any artisan command during the "hang up" it takes forever. Lets say you run any artisan command at 16:24 this command is not resolved until 16:27:31 (when the system is "locked out")

I have no more ideas... Have looked in logs and all that but NO CLUE. I think is not Laravel, maybe is a server issue. Server load is really little, is a droplet for a private app with 15 users. Mysql queries are not slow (I have activate the slow query log)

Cron log:

Sep 30 16:20:01 localhost CROND[28616]
Sep 30 16:21:01 localhost CROND[854]
Sep 30 16:22:02 localhost CROND[988]
Sep 30 16:23:01 localhost CROND[1062]
Sep 30 16:24:01 localhost CROND[1132]
Sep 30 16:25:01 localhost CROND[1199]
Sep 30 16:26:01 localhost CROND[1255]
Sep 30 16:27:01 localhost CROND[1315]
Sep 30 16:28:01 localhost CROND[1411]
Sep 30 16:29:01 localhost CROND[1508]
Sep 30 16:30:01 localhost CROND[1599]
Sep 30 16:31:01 localhost CROND[1670]
Sep 30 16:32:01 localhost CROND[1742]
Sep 30 16:33:01 localhost CROND[1807]
Sep 30 16:34:01 localhost CROND[1874]
Sep 30 16:35:01 localhost CROND[1936]
Sep 30 16:36:01 localhost CROND[1995]
Sep 30 16:37:01 localhost CROND[2062]

Scheduler log:

[2018-09-30 16:20:12] production.INFO: schedule call  
[2018-09-30 16:21:01] production.INFO: schedule call  
[2018-09-30 16:22:02] production.INFO: schedule call  
[2018-09-30 16:23:01] production.INFO: schedule call  
[2018-09-30 16:27:31] production.INFO: schedule call  
[2018-09-30 16:27:31] production.INFO: schedule call  
[2018-09-30 16:27:31] production.INFO: schedule call  
[2018-09-30 16:27:31] production.INFO: schedule call  
[2018-09-30 16:28:01] production.INFO: schedule call  
[2018-09-30 16:29:01] production.INFO: schedule call
[2018-09-30 16:30:01] production.INFO: schedule call
[2018-09-30 16:31:01] production.INFO: schedule call
[2018-09-30 16:32:02] production.INFO: schedule call
[2018-09-30 16:33:01] production.INFO: schedule call
[2018-09-30 16:37:53] production.INFO: schedule call
[2018-09-30 16:37:53] production.INFO: schedule call
[2018-09-30 16:37:53] production.INFO: schedule call
[2018-09-30 16:37:53] production.INFO: schedule call

Answer 1

maybe you need write call log , but not ping received log. Maybe you received ping with delay, and not call schedule.

Answer 2

The issue was caused by depleted entropy by PHP script.

To resolve the issue generate entropy by using haveged daemon:

1. Enable EPEL repository:

   yum install epel-release

2. Install daemon with the following command and enable it:

   yum install haveged chkconfig haveged on systemctl start haveged