Why pcsd leaves stalled connections in CLOSE_WAIT state?

Solution Verified - Updated -

Issue

While pcsd is running it leaves stalled connections in CLOSE_WAIT state which indicates the other end of the connection has been closed while the local end is still waiting for the application to close. This doesn't affect pcsd nor cluster operation as such but might have external effects i.e. flooding system log with notifications about INVALID packets if iptables/firewalld is configured to log ctstate INVALID packets. There is situation when one side sends closure request (FIN packet), remote side (client) acks that FIN request, but does not send its own FIN (which would be expected for proper connection closure process) for long time, and keeps the socket on the client side in CLOSE_WAIT state.
After some time the client finally sends the FIN, but as it takes too long time, the remote end already closed the connection based on timeout, and as such the last (late send) packets are considered as not legitimate, and therefore logged.

#  netstat -laputen | grep 2224
tcp       32      0 10.20.30.40:37372     10.20.30.40:2224      CLOSE_WAIT  0          318652188  1781/ruby
tcp       32      0 10.20.30.40:31713     10.20.30.41:2224      CLOSE_WAIT  0          318659641  1781/ruby
tcp       32      0 10.20.30.40:30813     10.20.30.41:2224      CLOSE_WAIT  0          318546897  1781/ruby
tcp       32      0 10.20.30.40:36472     10.20.30.40:2224      CLOSE_WAIT  0          318542722  1781/ruby
tcp       32      0 10.20.30.40:29931     10.20.30.41:2224      CLOSE_WAIT  0          318441750  1781/ruby
tcp       32      0 10.20.30.40:35594     10.20.30.40:2224      CLOSE_WAIT  0          318438254  1781/ruby
tcp6       0      0 :::2224                 :::*                    LISTEN      0          23943      1781/ruby

Environment

  • Red Hat Enterprise Linux 7
  • pacemaker cluster

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