for a program with a lot of logs (observed with 3+ million records), clicking Download All will create a 9-byte file containing 'undefined'. UI appears to be attempting to batch them all up where instead it should stream.
Fixed a problem with using "Download All" logs in the browser log viewer by having it fetch and stream the response to the client.
I believe I also ran into this issue when the backend returned no logs for an endpoint.
CDAP version was 3.5.0, distributed.