Under MRI, the following code will result in fetching https://www.google.com/. The last two lines are "0" and blank (chunked transfer encoding over http).

However, under JRuby (tested JRuby 1.7.16.1 and 1.7.9), this hangs.

Under MRI, it successfully reads the full HTTP request and the last line output (bytes read) is 52460. However, under JRuby, it hangs in IO::select after about the 30th iteration, but is nondeterministic in behavior (though the nondeterminism may be due to Google's webservers varying its responses and variations in TCP timing).

Jruby last output example:

29: 39149
30: 40542
31: 41935

In general, JRuby gets about 30 or 31 iterations (IO::select + sysread), and around 38kb-40kb of data before the next IO::select blocks forever.

If I change the timeout in IO::select to be 1 second instead of nil, the IO::select will time out after 1 second AND the next sysread() will give me data.

Full code:

require "socket"
require "openssl"

s = TCPSocket.new("www.google.com", 443)
o = OpenSSL::SSL::SSLSocket.new(s)
o.connect

o.write("GET / HTTP/1.1\r\n")
o.write("Host: www.google.com\r\n")
o.write("\r\n")
o.flush()

bytes = 0
count = 0
data = ""
while true
  count += 1
  r, w, e = IO.select([o], nil, nil, nil)
  data <<  o.sysread(16384)
  puts "#{count}: #{data.bytesize}"
  # Chunked encoding break
  break if data =~ /0\r\n\r\n$/m
end