Varnish FetchError overflow

Question

I am Getting a lot of varnish 503 error un uncached pages , all these error have one thing in common , checking varnish logs it stats "FetchError overflow". Also error is not consistent , sometimes its error and other times page open Perfectly. My guess its some kind of memory buffer overflow, can any one ever witnessed same error , or can point me to some Place. Version of Varnish is 5.2

Retiring

Did you try to increase in /etc/default/varnish parameter workspace_backend i.e. to 131072? try adding there i.e. following -p http_resp_hdr_len=65536 -p http_resp_size=98304 -p workspace_backend=131072. Restart of Varnish-service is needed after those changes. – Griffiths

i can confirm @ElvinRisti 's solution, although i had to set even higher buffer sizes. – Efik

@Efik How do you determine the proper buffer sizes etc to set these to? – Embitter

@Embitter best guess + trial and error. there is no big secret :) – Efik

Answer 1

There are several varnish parameters you can try to add/increase in /etc/default/varnish to fix these issues. Adjust the sizes and see what works in your situation.

E.g.:

-p http_resp_hdr_len=32M -p http_resp_size=32M -p http_req_hdr_len=32M -p http_req_size=32M -p workspace_backend=32M -p workspace_client=32M

Make sure to reload Varnish after changing configs.

Shinbone