Be more hostile with sockets that write block. Fixes #449

lib/puma/const.rb

@@ -41,6 +41,10 @@ module Puma
     # for the request
     FIRST_DATA_TIMEOUT = 30
 
+    # How long to wait when getting some write blocking on the socket when
+    # sending data back
+    WRITE_TIMEOUT = 10
+
     DATE = "Date".freeze
 
     SCRIPT_NAME = "SCRIPT_NAME".freeze

lib/puma/server.rb

@@ -779,10 +779,13 @@ module Puma
         begin
           n = io.syswrite str
         rescue Errno::EAGAIN, Errno::EWOULDBLOCK
-          IO.select(nil, [io], nil, 1)
+          if !IO.select(nil, [io], nil, WRITE_TIMEOUT)
+            raise ConnectionError, "Socket timeout writing data"
+          end
+
           retry
         rescue  Errno::EPIPE, SystemCallError, IOError
-          return false
+          raise ConnectionError, "Socket timeout writing data"
         end
 
         return if n == str.bytesize