Varnish Enterprise

Transit Buffer

Enabling the transit buffer feature allows Varnish to pace backend streaming passes to not consume too much memory. The varnishd feature transit_buffer sets the maximum number of bytes that the client can be ahead of the backend during the streaming pass.


Global enable

This enables transit buffering for all streaming passes. Varnish will let the client be 1 MiB ahead of the backend before waiting. This will not reduce the performance of streaming transfers.

varnishd -p transit_buffer=1M

VCL enable

This enables transit buffering for the current backend fetch operation.

sub vcl_backend_response {
	set beresp.transit_buffer = 1M;