Proxying with puma seems to be unreliable even with non-chunked encoding

[pedrocr]

While creating a testcase for bug #6 I ended up finding an unreliable result with proxying non-chunked content. Here's the testcase:

https://github.com/pedrocr/camerasink/blob/b01aac64e8aaef96f8527f6e29768cc1f5f6199b/testcases/puma_unreliable_proxying.ru

Again this is runnable as "rackup puma_unreliable_proxying.ru".

Then asking for the same resource multiple times from the original server works fine:

$ curl http://localhost:9000
Hello!
pedrocr@wintermute:~$ curl http://localhost:9000
Hello!
pedrocr@wintermute:~$ curl http://localhost:9000
Hello!
pedrocr@wintermute:~$ curl http://localhost:9000
Hello!
pedrocr@wintermute:~$ curl http://localhost:9000
Hello!

But doing the same from the proxy server sometimes returns an empty result:

pedrocr@wintermute:~$ curl http://localhost:9292
Hello!
pedrocr@wintermute:~$ curl http://localhost:9292
pedrocr@wintermute:~$ curl http://localhost:9292
Hello!

[whitehat101]

I was just curious, so I wrote a test for your test.

# puma_unreliable_proxying_test.rb
cnt = 0
1000.times do
  str = `curl http://localhost:9292 --silent`
  cnt += 1 if str == "Hello!\n"
end

puts cnt

When I commented the puma require and WEBrick was used, 1000/1000 requests were proxied each time.

When using puma, between 970 and 980 requests would be proxied, and the remainder returned an empty string.

I did two 10k runs. They proxied 9741 and 9734 requests.

puma version 2.11.3
rack-streaming-proxy 2.0.1