memory errors on startup in postgresql 9.6 log - MAP_HUGETLB failed On postgresql startup, I see this in the log files


  2017-07-17 05:21:01.743 UTC  > LOCATION:  CreateAnonymousSegment, pg_shmem.c:484
  2017-07-17 05:21:01.868 UTC  > LOG:  00000: redirecting log output to logging collector process
  2017-07-17 05:21:01.868 UTC  > HINT:  Future log output will appear in directory "pg_log".
  2017-07-17 05:21:01.868 UTC  > LOCATION:  SysLogger_Start, syslogger.c:622
  2017-07-21 05:46:01.680 UTC  > DEBUG:  00000: logger shutting down
  2017-07-21 05:46:01.680 UTC  > LOCATION:  SysLoggerMain, syslogger.c:490
  2017-07-21 05:46:01.973 UTC  > DEBUG:  00000: mmap(8264876032) with MAP_HUGETLB failed, huge pages disabled: Cannot allocate memory


I have never used huge pages - turning on huge_pages in postgres.conf does not help, I get different errors and the server will not start. I am unfamiliar with these settings.  

Please help point me in the right direction to explore why these errors are occurring and what I should do about them - adjustments to memory settings, logging (it is set very high) vacuuming, or what? 

What parts of the PostgreSQL manual are relevant?

Stack:  postgresql 9.6 on aws ec2 generic linux

UPDATE:  This post was originally written about things I noticed on installing a backup utility, and how that appeared to be causing errors, then I noticed a server without the utility is logging the same messages.
Own experience suggests that this is due to PostgreSQL running out-of-memory.

For instance, I ran into this error when attempting to bump max_connections up to a very high value (say, 2000) on a "small" server.