Large Number of DAP (Data Access Pack) TCP Sockets have CLOSE_WAIT Status (Doc ID 1552849.1)

Last updated on FEBRUARY 21, 2019

Applies to:

Symptoms

The Data Access Pack (DAP) application is not closing down its TCP port connections which are left in CLOSE_WAIT state.  These TCP ports remain in the CLOSE_WAIT state and are not cleared out and accumulate over time.

Example of problem scenario: 

Setup:

•  DAP communicating with a remote system on port 8001
•  The remote system timeout on inactive port is 30 seconds, before sending out a TCP FIN message to DAP
•  persistentConnectionCheckTimeout parameter set, as per <note 1513094.1>

1. DAP establishes a connection
2. DAP message is sent out, the message is sent successfully
   TCP connection Status:  

  Fri Apr  5 12:43:28 GMT 2013 

3. After 30 seconds inactivity, the remote server decides to close the TCP connection and initiates the TCP disconnection procedure to DAP
4. DAP gets the fin and turns its TCP port into CLOSE-WAIT
   TCP connection status:
 
  Fri Apr  5 12:44:02 GMT 2013 

5. After 30 seconds, the TCP scoket is still in CLOSE_WAIT and is still not cleared out.

The CLOSE_WAIT state is temporary and should only remain for a split second, between the first FIN and the last ACK, but remains forever.

Cause

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