Varnish Enterprise

Transit Buffer


Enabling this feature allows Varnish to pace backend streaming passes so that they don’t 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

varnishd -p transit_buffer=1M

Enable 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.

VCL enable

sub vcl_backend_response {
	set beresp.transit_buffer = 1M;

Enable transit buffering for the current backend fetch operation.