Xin
the retry_policy in the pasted config seems irrelevant here. tho the retry_policy I added to ext_proc was through the base::grpcService protocol, eventually it will get to the router as well....
it might be this line: https://github.com/envoyproxy/envoy/blob/b0d58be31c2d7fe3ea8fd620c7aedb6b09a4bb89/source/extensions/filters/http/ext_proc/ext_proc.cc#L589C1-L590C1 I guess your side stream grpc didn't return anything to Envoy? could you try in the response add/return 10 bytes for each rpc? if...
cc @stevenzzzz