ìíîæåñòâî ñîåäèíåíèé â TIME_WAIT îò nginx

CoolCold coolcold at coolcold.org
Tue Jan 20 22:37:51 MSK 2009

Hello Leonid,

Tuesday, January 20, 2009, 7:41:24 PM, you wrote:

LP> На одном из серверов наблюдал странную картину. Из мира к nginx не более 500 соединений. Но от nginx к apache более 2000, из которых почти все в TIME_WAIT. С чем это может быть связано? Нагрузки
LP> почти нету.
The design of TCP places the TIME-WAIT TCB at the endpoint that closes the connection; this decision conflicts with the semantics of many application protocols. The File Transfer Protocol (FTP)[4] and HTTP both interpret the closing of the transport connection as an end-of-transaction marker. In each case, the application protocol requires that servers close the transport connection, and the transport protocol requires that servers incur a memory cost if they do. Protocols that use other methods of marking end-of-transaction, e.g., SUN RPC over TCP[5], can have the clients close connections at the expense of a more complex application protocol.

from http://www.isi.edu/touch/pubs/infocomm99/infocomm99-web/


3.2  Closing and Reopening a Connection

      When a TCP connection is closed, a delay of 2*MSL in TIME-WAIT
      state ties up the socket pair for 4 minutes (see Section 3.5 of
      [Postel81].  Applications built upon TCP that close one connection
      and open a new one (e.g., an FTP data transfer connection using
      Stream mode) must choose a new socket pair each time.

from http://www.faqs.org/rfcs/rfc1185.html

np: none

Best regards,

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