Hi, Zachary Zolton, Joe Williams and I stumbled on an awkward part of
CouchDB's (actually MochiWeb's) configuration that makes working over
a slow connection problematic. When receiving a large unchunked
upload, MochiWeb calls
gen_tcp:recv(Socket, Length = 1048576, Timeout = 10000)
which says "pull 1MB off the socket in 10 seconds, or timeout". This
is a bit crazy, as we'd definitely like to support e.g. replication
with CouchDB servers over slower links than 100KB/s.
I tried to do a little digging to see what recourse we have. We can
of course play the tuning game adjusting the length and timeout until
we're happy, but I think it'd be nicer to never timeout a connection
that is still sending data. From the gen_tcp man page
The Length argument is only meaningful when the socket is in raw
mode and denotes the number of bytes to read. If Length = 0, all
available bytes are returned. If Length > 0, exactly Length
bytes are returned, or an error; possibly discarding less than
Length bytes of data when the socket gets closed from the other
side.
The optional Timeout parameter specifies a timeout in millisec-
onds. The default value is infinity.
I don't know what the behavior is when there are 0 bytes available on
the socket -- does gen_tcp:recv just keep returning 0 and leave it to
us to implement the timeout, or can we do something like
gen_tcp:recv(Socket, 0, 10000)
Best, Adam
