Joomla visitors module showing a growing visitors amount.

[Handy84]

Steps to reproduce the issue

visit the Joomla 3.8.4 site with various browsers the amount of visitors will increase but never drops back.
Php version curently running 7.1.13

I have detected this issue on various recently updated Joomla sites...

Expected result

The visitors amount displayed in the users online module equals the actual sessions open.

Actual result

It seems that the amount of visitors only will increase over time I see numbers of 600+ !

System information (as much as possible)

Php version curently running 7.1.13
installed Joomla version: 3.8.4
Joomla! 3.8.4 Stable [ Amani ] 30-January-2018 15:00 GMT
Database version: 5.5.5-10.0.29-MariaDB-cll-lve
Joomla Platform version: Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT

Additional comments

A .htaccess construction is inplace to prevent backend visit's.

The issue appears on various templates and sites, also on the Breez3 standard template.

My session tables are growing larger as well...

[alikon]

should be fixed by #19514

[csthomas]

If your session handler is database and value of ini_get('session.gc_probability'); is equal to 0 then php won't clear your database table #__session at all.

[csthomas]

See http://php.net/manual/pl/session.configuration.php#115842

[Handy84]

@csthomas Thanks for your comments. Indeed php is not clearing my database table so I wrote my own cronjob to do this.
The suggested code does not seem to work.