client.socket.tcpi_delta_retrans

INTEGER, read-only.

Available inrecvdeliverlogerror

The number of transmitted packets in the current connection that contained data being retransmitted measured between when this request started and now. For HTTP/1, this is the number of retransmissions associated with this HTTP request. For multiplexed versions of HTTP (e.g., HTTP/2) the number cannot be accurately ascribed to any particular HTTP request. This metric primarily covers the response message data and therefore is most meaningful after that has been sent (e.g., in vcl_log). Bytes the HTTP stack has sent by the time this metric is read may not have been sent successfully to the client yet due to other system buffers and therefore more retransmissions are still possible after VCL is no longer executing.

Try it out

client.socket.tcpi_delta_retrans is used in the following solution recipes. Recipes apply VCL to real-world use cases and can be deployed as-is, or adapted for your own service. See the full list of recipesfor more inspiration.

Click RUN on a sample below to provision a Fastly service, execute the code on Fastly, and see how the function behaves.

Comprehensive logging

Fastly offers a myriad of different variables that you can log. See and test a large collection here.