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Add a warning in documentation about memory consumption on varnish #281
We use the user context cache for some months on a heavy load media website. And we were having since the beginning inconsistence on random use case (disconnected user, blank esi, bad hash, ....).
Over the months inconsistence grew up until this week where it was happening at a faster peace.
We are using the following features from varnish / fos http cache :
After some brainfuck debugging we discover that Varnish has a specific configuration for memory used when dealing with header (sess_workspace in varnish 3 , workspace_client / workspace_backend in varnish 4)
Using all of this features makes varnish hit the limit pretty often of the default configuration (64k memory per request / session by default), specially when doing regex against a big header (like a regsuball on the Cookie in our case).
Maybe it will be a good thing to add a warning about this in documentation at the top of varnish reference to alert user on this.
One of the good way to monitor this use case is to check the LostHeader tag in varnishlog / varnishtop which indicates that varnish had to drop a Header because of workspace memory overflow.
this is interesting! yes, i agree its good to add such things to the documentation. should we add a Troubleshooting main section? i think adding it to the Caching Proxy Configuration > Varnish Configuration page is overloading that page. it could however have a note somewhere to this one. do you think the cookie case is the most likely to cause troubles? then the cross-reference note should go somewhere near http://foshttpcache.readthedocs.org/en/latest/varnish-configuration.html#cleaning-the-cookie-header