Re: Swap on postgres master server

Ok thanks I will try that.
But do you know if there is any way to avoid this?

vm.swapiness? or anything on the postgres conf?

Il giorno mar 16 ott 2018 alle ore 15:17 Bob Jolliffe <bobjolliffe(at)gmail(dot)com>
ha scritto:

> I guess you can run swapoff (followed by swapon). That will free up
> whatever is currently swapped. Beware if the system is actively
> swapping then swapoff can take some time. But it seems not in your
> case.
> On Tue, 16 Oct 2018 at 10:48, Nicola Contu <nicola(dot)contu(at)gmail(dot)com> wrote:
> >
> > No it is not probably used, because I can't find it in any way as I said.
> >
> > I run your commands :
> >
> > [root(at)usnyh-cmd1 ~]# vmstat 1
> > procs -----------memory---------- ---swap-- -----io---- -system--
> ------cpu-----
> > r b swpd free buff cache si so bi bo in cs us sy
> id wa st
> > 3 2 7505332 14545468 13692 241436784 0 0 47 115 0 0
> 11 2 84 2 0
> > 3 2 7505332 14490408 13692 241436928 0 0 0 248 6153 2013
> 3 1 93 3 0
> > 1 2 7505332 14474672 13692 241436800 0 0 0 1124 4905 1454
> 3 1 93 3 0
> > 4 2 7505332 14381156 13692 241436832 0 0 0 96 5322 1782
> 2 1 94 3 0
> > ^C
> > [root(at)usnyh-cmd1 ~]# ps -A --sort -rss -o comm,pmem | awk '
> > > NR == 1 { print; next }
> > > { a[$1] += $2 }
> > > END {
> > > for (i in a) {
> > > printf "%-15s\t%s\n", i, a[i];
> > > }
> > > }
> > > '
> > COMMAND %MEM
> > kworker/42:2 0
> > kworker/60:6H 0
> > kworker/60:2H 0
> > kdmwork-253:2 0
> > ksoftirqd/60 0
> > postmaster 15.2
> > kworker/9:0H 0
> >
> > So I'm just asking why it is still there with free -m and if there is
> any way to free that up if it is not used.
> >
> > Thanks
> >
> > Il giorno mar 16 ott 2018 alle ore 11:18 Hans Schou <
> hans(dot)schou(at)gmail(dot)com> ha scritto:
> >>
> >> Are you sure that swap is used actively? Maybe it had just been used
> during backup or something.
> >>
> >> Look after SwapIn/SwapOut (si/so) it should be '0'
> >> $ vmstat 1
> >> procs -----------memory---------- ---swap-- -----io---- -system--
> ------cpu-----
> >> r b swpd free buff cache si so bi bo in cs us sy
> id wa st
> >> 1 0 12 89344 46608 586384 0 0 12 8 30 86 0 0
> 99 0 0
> >>
> >> If you want to see the amount of ram used by each program with childs
> run this:
> >> ps -A --sort -rss -o comm,pmem | awk '
> >> NR == 1 { print; next }
> >> { a[$1] += $2 }
> >> END {
> >> for (i in a) {
> >> printf "%-15s\t%s\n", i, a[i];
> >> }
> >> }
> >> '
> >>
> >>
> >> On Tue, Oct 16, 2018 at 11:04 AM Nicola Contu <nicola(dot)contu(at)gmail(dot)com>
> wrote:
> >>>
> >>> Hello,
> >>> we are running Postgres 10.5 with master slave replication.
> >>>
> >>> These are our custom params
> >>>
> >>> archive_command = 'pgbackrest --stanza=cmdprod archive-push %p' #
> command to use to archive a logfile segment
> >>> archive_mode = on # enables archiving; off, on, or always
> >>> checkpoint_completion_target = 0.7 # checkpoint target duration, 0.0 -
> 1.0
> >>> default_text_search_config = 'pg_catalog.english' #
> >>> datestyle = 'iso, mdy' #
> >>> effective_cache_size = 120GB #
> >>> hot_standby = on # "on" allows queries during
> recovery
> >>> lc_messages = 'en_US.UTF-8' # locale for system
> error message
> >>> lc_monetary = 'en_US.UTF-8' # locale for monetary
> formatting
> >>> lc_numeric = 'en_US.UTF-8' # locale for number
> formatting
> >>> lc_time = 'en_US.UTF-8' # locale for time
> formatting
> >>> listen_addresses = '*' # defaults to 'localhost', '*' = all
> >>> log_autovacuum_min_duration = 1000ms # -1 disables, 0 logs all
> actions and
> >>> log_checkpoints = on #
> >>> log_line_prefix = '%t [%r] [%p]: [%l-1] db=%d,user=%u ' #
> >>> log_lock_waits = on # log lock waits >=
> deadlock_timeout
> >>> log_min_duration_statement = 1000ms # -1 is disabled, 0 logs
> all statements
> >>> log_statement = 'ddl' # none, ddl, mod, all
> >>> log_temp_files = 1024kB # log temporary files
> equal or larger
> >>> maintenance_work_mem = 2GB #
> >>> max_connections = 220 #
> >>> max_parallel_workers_per_gather = 8 # taken from
> max_worker_processes
> >>> max_wal_size = 2GB #
> >>> min_wal_size = 1GB #
> >>> pg_stat_statements.max = 10000 #
> >>> pg_stat_statements.track = all #
> >>> port = 5432 # port number which Postgres
> listen
> >>> shared_buffers = 10GB #
> >>> shared_preload_libraries = 'pg_stat_statements' # (change
> requires restart)
> >>> synchronous_standby_names = '1 ( "usnyh2" )' # comment out during
> upgrade
> >>> track_activity_query_size = 16384 # (change requires restart)
> >>> track_io_timing = on #
> >>> wal_buffers = 16MB #
> >>> wal_keep_segments = 100 #
> >>> wal_level = replica # minimal, replica, or logical
> >>> work_mem = 600MB #
> >>>
> >>> This server is on Centos 7 and the strange thing is that we see a lot
> of swap usage :
> >>>
> >>> [root(at)usnyh-cmd1 ~]# free -m
> >>> total used free shared buff/cache
> available
> >>> Mem: 257652 7555 5559 12804 244536
> 236036
> >>> Swap: 16383 7326 9057
> >>>
> >>> 7GB used.
> >>>
> >>> But can't see it from any of the commands like top etc.
> >>> I am sure it is postgres because it is the only service running on
> that machine.
> >>>
> >>> Is there anything we can do?
> >>> On the sync slave, the usage is just 400MB.
> >>>
> >>> Any trick?
> >>>
> >>> Thanks a lot,
> >>> Nicola
>