Varnish restart because of ram filled issue

[Hamidreza Hosseini]

Hi,
I have some varnish ram in production that I'm using it for 1 Year
I had this problem since first time that I install it but Now because we have so many request , the varnish ram will filled and crash and it destroys my backend cluster
The whole ram is 54GB but I adjust 43 GB ram to it in systemd:

ExecStart=/usr/sbin/varnishd -j unix,user=vcache -F -a :6081 -T localhost:6082 -f /etc/varnish/default.vcl -S /etc/varnish/secret -s malloc,43g -i varnish

what should I do for this problem??
why varnish doesnt prevent ram filled?
Is there any config in varnish that I tell it you can not eceed from this amount and if you reach that amount you MUST free your cache from the first input?(This feature is really important because I think because I have 5 core cpu onj server, systemd cant understand the limitation that I'm adjusting, it should balance in varnish...)

OS: ubuntu
Varnish version:
varnishd (varnish-6.0.5 revision 3065ccaacc4bb537fb976a524bd808db42c5fe40)
Copyright (c) 2006 Verdens Gang AS
Copyright (c) 2006-2019 Varnish Software AS




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