Created attachment 333154 [details] [review]
multiudpsink: Initialize bytes_sent field.

Under higher packet rates I observed that clients randomly drop out and stop receiving any data.  This happens when writing to the socket starts failing (e.g. because the socket returns an recoverable error such as EWOULDBLOCK).  The problem is that the bytes_sent field is never initialized to 0 and g_socket_send_messages() only sets this field when it actually wrote data for this message.  The fact that bytes_sent may be any random value when it fails to send a message then confuses gst_udp_messsages_find_first_not_sent().