TCP Socket (KGAS)
A session is waiting for an external host to provide requested data over a network socket. The time that this wait event tracks does not indicate a problem, and even a long wait time is not a reason to contact Oracle Support. It naturally takes time for data to flow between hosts over a network, and for the remote aspect of an application to process any request made to it. An application that communicates with a remote host must wait until the data it will read has arrived.
KGAS = > is a component in the server (wait event), that handles TCP/IP sockets on Oracle 10.2+; (packages -> UTL_TCP, UTP_SMTP, UTP_HTTP, ...)
When there is a network delay between application server and database server we see this event mostly. In our case we have found a report in an application which is generating huge data is the cause for this wait event.
This wait event some ties relates to mail server was down and the procedure tries to open a new connection with the SMTP server and it takes 75 /20 seconds to timeout on various operating systems.
On 10g Release 2 there is bug reported by oracle support BUG:5490208 - TIME WAIT TCP SOCKET KGAS