trying to track down postgres deaths

We have a problem with the postgres backend process terminating and
dropping core.  We believe it may be related to another problem we have
where the postgres backend process can not be properly terminated.

Question is, when I see:

#17 0x08151bc5 in ClosePostmasterPorts ()

in the stack trace of the process, is this an indicator that the backend
process was trying to shutdown?

I'm assuming that if it's trying to 'close ports' then it would be
shuting down the process.

Are there multiple scenarios where this routine would be called?

--
Until later, Geoffrey

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
  - Benjamin Franklin