[pgpool-general: 7234] Re: Idle connection in database
Nikhil Shetty
nikhil.dba04 at gmail.com
Mon Aug 31 15:14:48 JST 2020
Hi Tatsuo,
Thanks for the patch.Can I test this patch for both 4.0 and 4.1 versions of
Pgpool?
Thanks and Regards,
Nikhil
On Mon, Aug 31, 2020 at 7:02 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> Ok, attached is a new version of patch. I confirmed that performance
> was not changed.
>
> > Wait. It appears that the patch has a drawback: serious performance
> > degradation.
> >
> > pgbench -c 10 -n -p 11000 -C -t 10 test
> >
> > With connection_life_time = 10
> > tps = 3.316286 (including connections establishing)
> > tps = 3.680803 (excluding connections establishing)
> >
> > Without connection_life_time = 10
> > tps = 269.660238 (including connections establishing)
> > tps = 280.479690 (excluding connections establishing)
> >
> > Let me think if I coould enhance this...
> >
> >> Hi Nikhil,
> >>
> >> Ok, here is a patch to fix the problem.
> >>
> >> If serialize_accept is enabled, pgpool process tries to acquire
> >> semaphore locking so that there's only one process which can issue
> >> accept(2). Unfortunately if connection_life_time is enabled, an alarm
> >> is set right before the semaphore locking. So when the alarm fires,
> >> nothing happens because the process is waiting for semaphore locking.
> >>
> >> To fix this, "the alarm has been set" flag is added. If the flag is
> >> set, keep on checking for connection_life_time (plus margin) seconds
> >> until the alarm is fired, then expires the connection to backend.
> >>
> >> Patch attached.
> >>
> >>>> Hi Tatsuo,
> >>>>
> >>>> I was thinking on that line initially that may be because of
> >>>> serialize_accept it is not working but I didn't dwell into it much and
> >>>> didn't test it.
> >>>>
> >>>> Thanks for your input Tatsuo, you have been of immense help to find
> this
> >>>> problem.
> >>>>
> >>>> Will this fix, when it is done, be included in all 4.0 and 4.1
> versions?
> >>>
> >>> Not sure if there's actually a fix, but if there were a fix for this,
> >>> it will be definitely included in 4.0 and 4.1 branches.
> >>>
> >>>> On Sun, Aug 30, 2020, 14:08 Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> >>>>
> >>>>> Ok, I found that if following is set:
> >>>>>
> >>>>> serialize_accept=on
> >>>>>
> >>>>> then, connection_life_time does not work. (The alarm is not
> >>>>> fired). Don't know why but I am going to fix this.
> >>>>>
> >>>>> > Hi Tatsuo,
> >>>>> >
> >>>>> > I am using Pgpool v4.1.1.
> >>>>> >
> >>>>> > I have seen similiar behaviour in v4.0.9 as well.
> >>>>> >
> >>>>> > Thanks and Regards,
> >>>>> > Nikhil
> >>>>> >
> >>>>> > On Sun, Aug 30, 2020, 13:11 Tatsuo Ishii <ishii at sraoss.co.jp>
> wrote:
> >>>>> >
> >>>>> >> Ok, I have tried with your test data and pgpool settings. Also I
> added
> >>>>> >> log_disconnections to postgresql.conf so that when Pgpool-II
> >>>>> >> disconnects backend. However I was not able to reproduce your
> >>>>> >> problem. Pgpool-II worked as expected (10 seconds after the test
> >>>>> >> script ends, connection was terminated on all backends).
> >>>>> >>
> >>>>> >> What version of Pgpool-II are you using?
> >>>>> >>
> >>>>> >> > Hi Tatsuo,
> >>>>> >> >
> >>>>> >> >
> >>>>> >> > No, because my primary has node ID 0 and standby has node ID 1.
> >>>>> >> >
> >>>>> >> > Patch will help if my primary node ID is not 0 rite?
> >>>>> >> >
> >>>>> >> > Thanks and Regards,
> >>>>> >> > Nikhil
> >>>>> >> >
> >>>>> >> >
> >>>>> >> > On Sun, Aug 30, 2020, 12:19 Tatsuo Ishii <ishii at sraoss.co.jp>
> wrote:
> >>>>> >> >
> >>>>> >> >> Before these tests, have applied the patch?
> >>>>> >> >>
> >>>>> >> >> > Hi Tatsuo,
> >>>>> >> >> >
> >>>>> >> >> >
> >>>>> >> >> > I have to reopen this issue because after a lot of debugging
> and
> >>>>> >> reading
> >>>>> >> >> > documentation on connection_life_time though there is not
> much of
> >>>>> it,
> >>>>> >> >> this
> >>>>> >> >> > parameter doesn't work as it should.
> >>>>> >> >> >
> >>>>> >> >> > First I want to be correct in my understanding that this
> parameter
> >>>>> >> >> > terminates cached backend connections in the database.So, I
> test a
> >>>>> >> simple
> >>>>> >> >> > scenario as follows:
> >>>>> >> >> >
> >>>>> >> >> > PGPOOL - 128.199.224.132
> >>>>> >> >> >
> >>>>> >> >> > *Parameters set for pooling*
> >>>>> >> >> > serialize_accept=on
> >>>>> >> >> > child_life_time=0
> >>>>> >> >> > child_max_connections=0
> >>>>> >> >> > client_idle_limit=0
> >>>>> >> >> > connection_life_time=10
> >>>>> >> >> >
> >>>>> >> >> > *I am running a mixed.sql file which contain below
> statements*
> >>>>> >> >> > BEGIN;
> >>>>> >> >> > SELECT CURRENT_TIMESTAMP;
> >>>>> >> >> > INSERT into t1 values(3);
> >>>>> >> >> > INSERT into t1 values(4);
> >>>>> >> >> > select pg_sleep(5);
> >>>>> >> >> > INSERT into t1 values(5);
> >>>>> >> >> > UPDATE t1 set id=4 where id=5;
> >>>>> >> >> > END;
> >>>>> >> >> >
> >>>>> >> >> > After executing some inserts it will sleep for 5 seconds and
> then
> >>>>> >> execute
> >>>>> >> >> > one update and an insert before closing the connection.
> >>>>> >> >> >
> >>>>> >> >> >
> >>>>> >> >> > *1) Status of nodes*
> >>>>> >> >> > -bash-4.2$ psql -h 128.199.224.132 -p 9999 -U enterprisedb
> >>>>> >> >> > psql.bin (11.6.13)
> >>>>> >> >> > Type "help" for help.
> >>>>> >> >> >
> >>>>> >> >> > edb=# show pool_nodes;
> >>>>> >> >> > node_id | hostname | port | status | lb_weight |
> role |
> >>>>> >> >> > select_cnt | load_balance_node | replication_delay |
> >>>>> >> replication_state |
> >>>>> >> >> > replication_syn
> >>>>> >> >> > c_state | last_status_change
> >>>>> >> >> >
> >>>>> >> >>
> >>>>> >>
> >>>>>
> ---------+-----------------+------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+----------------
> >>>>> >> >> > --------+---------------------
> >>>>> >> >> > 0 | 128.199.222.92 | 5445 | up | 0.000000 |
> primary |
> >>>>> 0
> >>>>> >> >> > | false | 0 |
> |
> >>>>> >> >> > | 2020-08-30 04:58:24
> >>>>> >> >> > 1 | 128.199.222.124 | 5445 | up | 1.000000 |
> standby |
> >>>>> 0
> >>>>> >> >> > | true | 0 |
> |
> >>>>> >> >> > | 2020-08-30 04:58:24
> >>>>> >> >> > (2 rows)
> >>>>> >> >> >
> >>>>> >> >> > *2) Running the mixed.sql file*
> >>>>> >> >> > -bash-4.2$ psql -h 128.199.224.132 -p 9999 -U enterprisedb -f
> >>>>> >> mixed.sql
> >>>>> >> >> > BEGIN
> >>>>> >> >> > current_timestamp
> >>>>> >> >> > ----------------------------------
> >>>>> >> >> > 30-AUG-20 10:31:47.396527 +05:30
> >>>>> >> >> > (1 row)
> >>>>> >> >> >
> >>>>> >> >> > INSERT 0 1
> >>>>> >> >> > INSERT 0 1
> >>>>> >> >> > pg_sleep
> >>>>> >> >> > ----------
> >>>>> >> >> >
> >>>>> >> >> > (1 row)
> >>>>> >> >> >
> >>>>> >> >> > INSERT 0 1
> >>>>> >> >> > UPDATE 1
> >>>>> >> >> > COMMIT
> >>>>> >> >> > -bash-4.2$
> >>>>> >> >> >
> >>>>> >> >> > *3) pool_pools output shows pgpool (pid - 31560) created one
> >>>>> >> connection
> >>>>> >> >> to
> >>>>> >> >> > master(pid - 31550) and one to standby (pid - 28954) *
> >>>>> >> >> >
> >>>>> >> >> > edb=# show pool_pools;
> >>>>> >> >> > pool_pid | start_time | pool_id | backend_id |
> database |
> >>>>> >> >> > username | create_time | majorversion |
> minorversion |
> >>>>> >> >> > pool_counter | pool_
> >>>>> >> >> > backendpid | pool_connected
> >>>>> >> >> >
> >>>>> >> >>
> >>>>> >>
> >>>>>
> ----------+---------------------+---------+------------+----------+--------------+---------------------+--------------+--------------+--------------+------
> >>>>> >> >> > -----------+----------------
> >>>>> >> >> > 31560 | 2020-08-30 04:51:54 | 0 | 0 |
> edb |
> >>>>> >> >> > enterprisedb | 2020-08-30 05:01:47 | 3 | 0
> |
> >>>>> 1
> >>>>> >> >> > | 31550
> >>>>> >> >> > | 0
> >>>>> >> >> > 31560 | 2020-08-30 04:51:54 | 0 | 1 |
> edb |
> >>>>> >> >> > enterprisedb | 2020-08-30 05:01:47 | 3 | 0
> |
> >>>>> 1
> >>>>> >> >> > | 28954
> >>>>> >> >> > | 0
> >>>>> >> >> >
> >>>>> >> >> > *4) Status of process id 31550 on master.After the run, as
> seen
> >>>>> below
> >>>>> >> on
> >>>>> >> >> > the database is idle*
> >>>>> >> >> >
> >>>>> >> >> > -bash-4.2$ ps -ef |grep 224.132
> >>>>> >> >> > enterpr+ 31550 9148 0 05:01 ? 00:00:00 postgres:
> >>>>> enterprisedb
> >>>>> >> >> edb
> >>>>> >> >> > 128.199.224.132[49656] idle
> >>>>> >> >> >
> >>>>> >> >> > *5) Status of processid 31560 on pgpool.* *After the run, as
> seen
> >>>>> >> below
> >>>>> >> >> > pgpool has released connection as soon as transaction
> completes*
> >>>>> >> >> > [root at pgpool-p pgpool4.1]# ps -ef |grep 31560
> >>>>> >> >> > enterpr+ 31560 31557 0 04:51 ? 00:00:00 pgpool: wait
> for
> >>>>> >> accept
> >>>>> >> >> lock
> >>>>> >> >> >
> >>>>> >> >> >
> >>>>> >> >> > *6) After 10 seconds, this cached connection on database
> should
> >>>>> have
> >>>>> >> been
> >>>>> >> >> > terminated as per my understanding of connection_life_time
> >>>>> parameter
> >>>>> >> but
> >>>>> >> >> as
> >>>>> >> >> > seen below it has not terminated*
> >>>>> >> >> > edb=# select * from pg_stat_activity where client_addr
> >>>>> >> >> ='128.199.224.132';
> >>>>> >> >> > -[ RECORD 1 ]----+---------------------------------
> >>>>> >> >> > datid | 67127
> >>>>> >> >> > datname | edb
> >>>>> >> >> > pid | 31550
> >>>>> >> >> > usesysid | 10
> >>>>> >> >> > usename | enterprisedb
> >>>>> >> >> > application_name | psql.bin
> >>>>> >> >> > client_addr | 128.199.224.132
> >>>>> >> >> > client_hostname |
> >>>>> >> >> > client_port | 49656
> >>>>> >> >> > backend_start | 30-AUG-20 10:31:47.380345 +05:30
> >>>>> >> >> > xact_start |
> >>>>> >> >> > query_start | 30-AUG-20 10:31:52.411607 +05:30
> >>>>> >> >> > state_change | 30-AUG-20 10:31:52.411714 +05:30
> >>>>> >> >> > wait_event_type | Client
> >>>>> >> >> > wait_event | ClientRead
> >>>>> >> >> > state | idle
> >>>>> >> >> > backend_xid |
> >>>>> >> >> > backend_xmin |
> >>>>> >> >> > query | DISCARD ALL
> >>>>> >> >> > backend_type | client backend
> >>>>> >> >> >
> >>>>> >> >> > Do not mind the timestamp, it is in IST for the above query.
> >>>>> >> >> >
> >>>>> >> >> > *7) From the pgpool logs, it sets the alarm after 10 sec but
> >>>>> doesn't
> >>>>> >> >> really
> >>>>> >> >> > close the connection after 10 seconds*
> >>>>> >> >> > Aug 30 05:01:52 Pgpool-p pgpool[*31560*]: [252-2] 2020-08-30
> >>>>> 05:01:52:
> >>>>> >> >> pid
> >>>>> >> >> > 31560: DETAIL: setting alarm after 10 seconds
> >>>>> >> >> >
> >>>>> >> >> > Attaching pgpool logs as well.
> >>>>> >> >> >
> >>>>> >> >> >
> >>>>> >> >> > On Wed, Aug 12, 2020 at 9:02 PM Nikhil Shetty <
> >>>>> nikhil.dba04 at gmail.com
> >>>>> >> >
> >>>>> >> >> > wrote:
> >>>>> >> >> >
> >>>>> >> >> >> Hi Tatsuo,
> >>>>> >> >> >>
> >>>>> >> >> >> Thank you, I will check how this works.
> >>>>> >> >> >>
> >>>>> >> >> >>
> >>>>> >> >> >> On Tue, Aug 11, 2020 at 5:52 PM Tatsuo Ishii <
> ishii at sraoss.co.jp>
> >>>>> >> >> wrote:
> >>>>> >> >> >>
> >>>>> >> >> >>> Hi Nikhil,
> >>>>> >> >> >>>
> >>>>> >> >> >>> > Hi Tatsuo,
> >>>>> >> >> >>> >
> >>>>> >> >> >>> > We are checking the patch internally before we go ahead
> and
> >>>>> >> deploy in
> >>>>> >> >> >>> > production.
> >>>>> >> >> >>>
> >>>>> >> >> >>> Ok.
> >>>>> >> >> >>>
> >>>>> >> >> >>> > If I want to set only one of either connection_life_time
> or
> >>>>> >> >> >>> > client_idle_limit. What do you recommend? Should I set
> >>>>> >> >> >>> > client_idle_limit=120 and connection_life_time=0, do you
> >>>>> foresee
> >>>>> >> any
> >>>>> >> >> >>> > effects of these settings for connection pooling?
> >>>>> >> >> >>>
> >>>>> >> >> >>> In general connection_life_time is better because:
> >>>>> >> >> >>>
> >>>>> >> >> >>> 1. when client_idle_limit expires, pgpool needs to fork a
> new
> >>>>> >> process,
> >>>>> >> >> >>> but connection_life_time does not.
> >>>>> >> >> >>>
> >>>>> >> >> >>> 2. when client_idle_limit expires, it looses mutiple
> connection
> >>>>> >> pools
> >>>>> >> >> >>> (this only applicatable fro max_pool > 1 case) because
> the
> >>>>> >> >> >>> connection pools the process hold go away.
> >>>>> >> >> >>>
> >>>>> >> >> >>> However if you have very short and frequent sessions, more
> alarm
> >>>>> >> >> >>> system calls with connection_life_time are required and
> maybe
> >>>>> >> >> >>> client_idle_limit wins in this case.
> >>>>> >> >> >>>
> >>>>> >> >> >>> > Thank you for your time and support.
> >>>>> >> >> >>> >
> >>>>> >> >> >>> > Thanks and Regards,
> >>>>> >> >> >>> > Nikhil
> >>>>> >> >> >>> >
> >>>>> >> >> >>> > On Mon, Aug 10, 2020 at 11:58 AM Tatsuo Ishii <
> >>>>> ishii at sraoss.co.jp
> >>>>> >> >
> >>>>> >> >> >>> wrote:
> >>>>> >> >> >>> >
> >>>>> >> >> >>> >> Hi Nikhil,
> >>>>> >> >> >>> >>
> >>>>> >> >> >>> >> I have been investigating if there's any case when
> >>>>> >> >> >>> >> connection_life_time is not working. Actually it *is*.
> If
> >>>>> primary
> >>>>> >> >> node
> >>>>> >> >> >>> >> is not node 0, connection_life_time does not work.
> Attached is
> >>>>> >> the
> >>>>> >> >> >>> >> patch to fix that. Please try, if you like.
> >>>>> >> >> >>> >>
> >>>>> >> >> >>> >> > According to your previous message, corresponding
> pgpool
> >>>>> >> process
> >>>>> >> >> was
> >>>>> >> >> >>> >> > not there, but PostgreSQL backend process were still
> >>>>> running. I
> >>>>> >> >> >>> >> > suspect the backend process was waiting for TCP/IP
> >>>>> connection
> >>>>> >> was
> >>>>> >> >> >>> >> > terminated. But to know what was actually happening,
> I was
> >>>>> >> waiting
> >>>>> >> >> >>> for
> >>>>> >> >> >>> >> > your response.
> >>>>> >> >> >>> >> >
> >>>>> >> >> >>> >> >>> "DISCARD ALL" and state idle. I will have to test
> again to
> >>>>> >> check
> >>>>> >> >> >>> the
> >>>>> >> >> >>> >> socket
> >>>>> >> >> >>> >> >>> status of pid.I will get back on this
> >>>>> >> >> >>> >> >
> >>>>> >> >> >>> >> > What was that?
> >>>>> >> >> >>> >> >
> >>>>> >> >> >>> >> >> Hi Tatsuo,
> >>>>> >> >> >>> >> >>
> >>>>> >> >> >>> >> >>
> >>>>> >> >> >>> >> >> Ant reason why connection_idle_limit doesn't remove
> backend
> >>>>> >> >> >>> connection
> >>>>> >> >> >>> >> >> after time limit is crossed
> >>>>> >> >> >>> >> >>
> >>>>> >> >> >>> >> >> Thanks and Regards,
> >>>>> >> >> >>> >> >> Nikhil
> >>>>> >> >> >>> >> >>
> >>>>> >> >> >>> >> >> On Sun, Aug 2, 2020, 12:48 Nikhil Shetty <
> >>>>> >> nikhil.dba04 at gmail.com
> >>>>> >> >> >
> >>>>> >> >> >>> >> wrote:
> >>>>> >> >> >>> >> >>
> >>>>> >> >> >>> >> >>> Hi Tatsuo,
> >>>>> >> >> >>> >> >>>
> >>>>> >> >> >>> >> >>> I want to correct my statement from previous email:
> >>>>> >> >> >>> >> >>>
> >>>>> >> >> >>> >> >>> From ps status *I could not see *that the process
> (18190
> >>>>> and
> >>>>> >> >> 18193)
> >>>>> >> >> >>> >> were
> >>>>> >> >> >>> >> >>> still present on pgpool but the backend process was
> still
> >>>>> >> >> present
> >>>>> >> >> >>> with
> >>>>> >> >> >>> >> >>> "DISCARD ALL" and state idle. I will have to test
> again to
> >>>>> >> check
> >>>>> >> >> >>> the
> >>>>> >> >> >>> >> socket
> >>>>> >> >> >>> >> >>> status of pid.I will get back on this
> >>>>> >> >> >>> >> >>>
> >>>>> >> >> >>> >> >>> On Sun, Aug 2, 2020 at 12:15 PM Nikhil Shetty <
> >>>>> >> >> >>> nikhil.dba04 at gmail.com>
> >>>>> >> >> >>> >> >>> wrote:
> >>>>> >> >> >>> >> >>>
> >>>>> >> >> >>> >> >>>> Hi Tatsuo,
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> >> Assuming you executed "show pool_pools" long
> after
> >>>>> >> >> 2020-08-01
> >>>>> >> >> >>> >> >>>> >> 06:21:26, that is very strange because
> >>>>> >> connection_life_time
> >>>>> >> >> >>> should
> >>>>> >> >> >>> >> >>>> >> have been already expired. I wonder if pgpool
> tried to
> >>>>> >> >> >>> disconnect
> >>>>> >> >> >>> >> the
> >>>>> >> >> >>> >> >>>> >> connection but failed. To check what actually
> happend,
> >>>>> >> can
> >>>>> >> >> you
> >>>>> >> >> >>> >> check
> >>>>> >> >> >>> >> >>>> >> ps status of pgpool process 18190 and 18193?
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> >> Also it would be nice you can examine the socket
> >>>>> status
> >>>>> >> of
> >>>>> >> >> >>> >> PostgreSQL
> >>>>> >> >> >>> >> >>>> >> backend 29321 and 29619, and pgpool socket
> status of
> >>>>> >> process
> >>>>> >> >> >>> 18190
> >>>>> >> >> >>> >> and
> >>>>> >> >> >>> >> >>>> >> 18193?
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> From ps status I could see that the process (18190
> and
> >>>>> >> 18193)
> >>>>> >> >> were
> >>>>> >> >> >>> >> still
> >>>>> >> >> >>> >> >>>> present on pgpool. I will have to test again to
> check the
> >>>>> >> >> socket
> >>>>> >> >> >>> >> status of
> >>>>> >> >> >>> >> >>>> pid.I will get back on this
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Meanwhile, I did some testing of my own for these
> two
> >>>>> >> >> parameters(
> >>>>> >> >> >>> >> >>>> client_idle_limit and connection_life_time ) and
> their
> >>>>> >> >> behaviour:
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *Test:*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Database IP:128.199.222.92(master)
> >>>>> >> >> >>> >> >>>> Pgpool IP: 128.199.224.132
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *Scenario1:*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> max_pool=1
> >>>>> >> >> >>> >> >>>> num_init_children=100
> >>>>> >> >> >>> >> >>>> serialize_accept=on
> >>>>> >> >> >>> >> >>>> child_max_connections=0
> >>>>> >> >> >>> >> >>>> child_life_time=0
> >>>>> >> >> >>> >> >>>> connection_life_time=60
> >>>>> >> >> >>> >> >>>> client_idle_limit=0
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *1. Connected to Pgpool and ran a query with
> \watch 1:*
> >>>>> >> >> >>> >> >>>> select count(*) from pgbench_accounts ;
> >>>>> >> >> >>> >> >>>> \watch 1
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020 07:25:54 AM UTC (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> count
> >>>>> >> >> >>> >> >>>> ---------
> >>>>> >> >> >>> >> >>>> 6000000
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *2. Checking session in database, one session is
> active
> >>>>> from
> >>>>> >> >> >>> pgpool*
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020
> 07:26:14 AM
> >>>>> UTC
> >>>>> >> >> >>> (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query |
> >>>>> usename
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> client_addr | count | state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >>
> >>>>> >> >> >>>
> >>>>> >> >>
> >>>>> >>
> >>>>>
> ------+-----------------------------------------+--------------+-----------------+-------+--------
> >>>>> >> >> >>> >> >>>> 3420 | select count(*) from pgbench_accounts ; |
> >>>>> >> enterprisedb
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> 128.199.224.132 | 1 | active
> >>>>> >> >> >>> >> >>>> (1 row)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *3. Stopped the query after sometime using Ctrl-C
> but
> >>>>> >> session
> >>>>> >> >> is
> >>>>> >> >> >>> still
> >>>>> >> >> >>> >> >>>> open*
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020 07:27:35 AM UTC (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> count
> >>>>> >> >> >>> >> >>>> ---------
> >>>>> >> >> >>> >> >>>> 6000000
> >>>>> >> >> >>> >> >>>> (1 row)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> ^Cedb=#
> >>>>> >> >> >>> >> >>>> edb=#
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *4. Checking session in database, state is now
> idle*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020
> 07:28:14 AM
> >>>>> UTC
> >>>>> >> >> (every
> >>>>> >> >> >>> 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query |
> >>>>> usename
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> client_addr | count | state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >>
> >>>>> >> >> >>>
> >>>>> >> >>
> >>>>> >>
> >>>>>
> ------+-----------------------------------------+--------------+-----------------+-------+-------
> >>>>> >> >> >>> >> >>>> 3420 | select count(*) from pgbench_accounts ; |
> >>>>> >> enterprisedb
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> 128.199.224.132 | 1 | idle
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *5. Checking session in database after 2 minutes,
> I can
> >>>>> >> still
> >>>>> >> >> see
> >>>>> >> >> >>> the
> >>>>> >> >> >>> >> >>>> database session idle*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020
> 07:30:02 AM
> >>>>> UTC
> >>>>> >> >> (every
> >>>>> >> >> >>> 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query |
> >>>>> usename
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> client_addr | count | state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >>
> >>>>> >> >> >>>
> >>>>> >> >>
> >>>>> >>
> >>>>>
> ------+-----------------------------------------+--------------+-----------------+-------+-------
> >>>>> >> >> >>> >> >>>> 3420 | select count(*) from pgbench_accounts ; |
> >>>>> >> enterprisedb
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> 128.199.224.132 | 1 | idle
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *6. Checking connection on pgpool server.
> connection is
> >>>>> >> still
> >>>>> >> >> open
> >>>>> >> >> >>> >> from
> >>>>> >> >> >>> >> >>>> pgpool to database*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> ps -ef|grep edb
> >>>>> >> >> >>> >> >>>> enterpr+ 24170 24162 0 06:51 ? 00:00:00
> pgpool:
> >>>>> >> >> >>> enterprisedb
> >>>>> >> >> >>> >> edb
> >>>>> >> >> >>> >> >>>> 128.199.222.92(34402) idle
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *7. After being idle for more than 60 seconds,
> >>>>> connections
> >>>>> >> are
> >>>>> >> >> >>> still
> >>>>> >> >> >>> >> open
> >>>>> >> >> >>> >> >>>> from pgpool and on database.Connection is removed
> from
> >>>>> >> pgpool
> >>>>> >> >> >>> server
> >>>>> >> >> >>> >> after
> >>>>> >> >> >>> >> >>>> I quit from the psql terminal but still present in
> the
> >>>>> >> >> database as
> >>>>> >> >> >>> >> show
> >>>>> >> >> >>> >> >>>> below:*
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020 07:34:26 AM UTC
> (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query | usename |
> client_addr |
> >>>>> >> count |
> >>>>> >> >> >>> state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>>
> >>>>> >>
> ------+--------------+--------------+-----------------+-------+-------
> >>>>> >> >> >>> >> >>>> 3420 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1 |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *Scenario2:*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> max_pool=1
> >>>>> >> >> >>> >> >>>> num_init_children=100
> >>>>> >> >> >>> >> >>>> serialize_accept=on
> >>>>> >> >> >>> >> >>>> child_max_connections=0
> >>>>> >> >> >>> >> >>>> child_life_time=0
> >>>>> >> >> >>> >> >>>> connection_life_time=0
> >>>>> >> >> >>> >> >>>> client_idle_limit=60
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *1. Connected to Pgpool and ran a query with
> \watch 1:*
> >>>>> >> >> >>> >> >>>> edb=# \! date
> >>>>> >> >> >>> >> >>>> Sat Aug 1 07:38:45 UTC 2020
> >>>>> >> >> >>> >> >>>> select count(*) from pgbench_accounts ;
> >>>>> >> >> >>> >> >>>> \watch 1
> >>>>> >> >> >>> >> >>>> edb=# select count(*) from pgbench_accounts ;
> >>>>> >> >> >>> >> >>>> count
> >>>>> >> >> >>> >> >>>> ---------
> >>>>> >> >> >>> >> >>>> 6000000
> >>>>> >> >> >>> >> >>>> (1 row)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *2. Checking session in database, one session is
> active
> >>>>> from
> >>>>> >> >> >>> pgpool*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020
> 07:39:55 AM
> >>>>> UTC
> >>>>> >> >> >>> (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query |
> >>>>> usename
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> client_addr | count | state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >>
> >>>>> >> >> >>>
> >>>>> >> >>
> >>>>> >>
> >>>>>
> -------+-----------------------------------------+--------------+-----------------+-------+--------
> >>>>> >> >> >>> >> >>>> 13427 | select count(*) from pgbench_accounts ; |
> >>>>> >> >> enterprisedb |
> >>>>> >> >> >>> >> >>>> 128.199.224.132 | 1 | active
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *3. Stopped the query after sometime using Ctrl-C
> but
> >>>>> >> session
> >>>>> >> >> is
> >>>>> >> >> >>> still
> >>>>> >> >> >>> >> >>>> open*
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020 07:41:39 AM UTC (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> count
> >>>>> >> >> >>> >> >>>> ---------
> >>>>> >> >> >>> >> >>>> 6000000
> >>>>> >> >> >>> >> >>>> ^Cedb=#
> >>>>> >> >> >>> >> >>>> edb=#
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *4. Checking session in database, state is now
> idle*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020
> 07:42:12 AM
> >>>>> UTC
> >>>>> >> >> >>> (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query |
> >>>>> usename
> >>>>> >> >> |
> >>>>> >> >> >>> >> >>>> client_addr | count | state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >>
> >>>>> >> >> >>>
> >>>>> >> >>
> >>>>> >>
> >>>>>
> -------+-----------------------------------------+--------------+-----------------+-------+-------
> >>>>> >> >> >>> >> >>>> 13427 | select count(*) from pgbench_accounts ; |
> >>>>> >> >> enterprisedb |
> >>>>> >> >> >>> >> >>>> 128.199.224.132 | 1 | idle
> >>>>> >> >> >>> >> >>>> (1 row)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *5. Checking session in database after 2 minutes,
> there
> >>>>> is
> >>>>> >> no
> >>>>> >> >> >>> session
> >>>>> >> >> >>> >> in
> >>>>> >> >> >>> >> >>>> the database.*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Sat 01 Aug 2020 07:42:42 AM UTC (every 1s)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query | usename | client_addr | count |
> state
> >>>>> >> >> >>> >> >>>>
> -----+-------+---------+-------------+-------+-------
> >>>>> >> >> >>> >> >>>> (0 rows)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *6. Checking connection on pgpool server. No
> connection
> >>>>> >> open in
> >>>>> >> >> >>> >> pgpool to
> >>>>> >> >> >>> >> >>>> database*
> >>>>> >> >> >>> >> >>>> ps -ef|grep edb
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> *Observations:*
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> With client_idle_limit of 60 seconds, all
> connections are
> >>>>> >> >> closed
> >>>>> >> >> >>> after
> >>>>> >> >> >>> >> >>>> being idle for more than 1 minute. I can see psql
> >>>>> session in
> >>>>> >> >> >>> database
> >>>>> >> >> >>> >> is
> >>>>> >> >> >>> >> >>>> still present as shown below, because
> >>>>> >> >> >>> >> >>>> I did not quit from psql terminal yet:
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> [root at master ~]# ps -ef |grep 128.199.224.132
> >>>>> >> >> >>> >> >>>> enterpr+ 13193 28563 0 07:38 pts/0 00:00:00
> /bin/bash
> >>>>> >> >> >>> /bin/psql -p
> >>>>> >> >> >>> >> >>>> 9999 -h 128.199.224.132
> >>>>> >> >> >>> >> >>>> enterpr+ 13198 13193 0 07:38 pts/0 00:00:00
> >>>>> >> /bin/psql.bin
> >>>>> >> >> -p
> >>>>> >> >> >>> 9999
> >>>>> >> >> >>> >> -h
> >>>>> >> >> >>> >> >>>> 128.199.224.132
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> From scenario 2( client_idle_limit = 60), we can
> say that
> >>>>> >> when
> >>>>> >> >> >>> >> >>>> client_idle_limit is triggered client is
> disconnected, no
> >>>>> >> >> database
> >>>>> >> >> >>> >> >>>> connection is in use but the session still remains
> on
> >>>>> >> >> server.If i
> >>>>> >> >> >>> >> start
> >>>>> >> >> >>> >> >>>> running query
> >>>>> >> >> >>> >> >>>> on same psql session, it will first reset
> connection and
> >>>>> >> then
> >>>>> >> >> run
> >>>>> >> >> >>> the
> >>>>> >> >> >>> >> >>>> query, this will again create a new connection to
> the
> >>>>> >> database.
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> From scenario 1(connection_life_time = 60), there
> is no
> >>>>> real
> >>>>> >> >> >>> benefit I
> >>>>> >> >> >>> >> >>>> see. I assumed the connections(DISCARD ALL)
> present in
> >>>>> >> database
> >>>>> >> >> >>> will
> >>>>> >> >> >>> >> be
> >>>>> >> >> >>> >> >>>> reused but each time I connected to the database,
> it
> >>>>> >> created a
> >>>>> >> >> new
> >>>>> >> >> >>> >> >>>> connection as seen below:
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> pid | query | usename |
> client_addr |
> >>>>> >> count
> >>>>> >> >> |
> >>>>> >> >> >>> state
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >>
> >>>>> >> >>
> >>>>>
> -------+--------------+--------------+-----------------+-------+-------
> >>>>> >> >> >>> >> >>>> 12895 | | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 3420 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12531 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12636 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12698 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12751 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12773 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12862 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> 12878 | DISCARD ALL | enterprisedb |
> 128.199.224.132 |
> >>>>> >> 1
> >>>>> >> >> |
> >>>>> >> >> >>> idle
> >>>>> >> >> >>> >> >>>> (9 rows)
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> Thanks and Regards,
> >>>>> >> >> >>> >> >>>> Nikhil
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>> On Sat, Aug 1, 2020 at 6:45 PM Tatsuo Ishii <
> >>>>> >> >> ishii at sraoss.co.jp>
> >>>>> >> >> >>> >> wrote:
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> >>>>> > Hi,
> >>>>> >> >> >>> >> >>>>> >
> >>>>> >> >> >>> >> >>>>> > Yes, we can see the pid
> >>>>> >> >> >>> >> >>>>> >
> >>>>> >> >> >>> >> >>>>> > show pool_pools;
> >>>>> >> >> >>> >> >>>>> > pool_pid | start_time | pool_id |
> backend_id
> >>>>> |
> >>>>> >> >> >>> database |
> >>>>> >> >> >>> >> >>>>> > username | create_time | majorversion
> |
> >>>>> >> >> minorversion
> >>>>> >> >> >>> |
> >>>>> >> >> >>> >> >>>>> > pool_counter | pool_backendpid | pool_connected
> >>>>> >> >> >>> >> >>>>> >
> >>>>> >> >> >>> >> >>>>> > 18190 | 2020-08-01 06:14:41 | 0 | 1
> >>>>> |
> >>>>> >> edb
> >>>>> >> >> >>> |
> >>>>> >> >> >>> >> >>>>> > enterprisedb | 2020-08-01 06:19:52 | 3
> | 0
> >>>>> >> >> >>> |
> >>>>> >> >> >>> >> 1
> >>>>> >> >> >>> >> >>>>> > | *29321* | 0
> >>>>> >> >> >>> >> >>>>> > 18193 | 2020-08-01 06:14:41 | 0 | 1
> >>>>> |
> >>>>> >> edb
> >>>>> >> >> >>> |
> >>>>> >> >> >>> >> >>>>> > enterprisedb | 2020-08-01 06:21:26 | 3
> | 0
> >>>>> >> >> >>> |
> >>>>> >> >> >>> >> 1
> >>>>> >> >> >>> >> >>>>> > | *29619 *| 0
> >>>>> >> >> >>> >> >>>>> >
> >>>>> >> >> >>> >> >>>>> >
> >>>>> >> >> >>> >> >>>>> > select pid,query,usename,state from
> pg_stat_activity
> >>>>> >> where
> >>>>> >> >> >>> >> >>>>> > client_addr='128.199.224.132' group by
> >>>>> usename,query,pid;
> >>>>> >> >> >>> >> >>>>> > pid | query | usename | state
> >>>>> >> >> >>> >> >>>>> > -------+--------------+--------------+-------
> >>>>> >> >> >>> >> >>>>> > *29321 *| DISCARD ALL | enterprisedb | idle
> >>>>> >> >> >>> >> >>>>> > *29619* | DISCARD ALL | enterprisedb | idle
> >>>>> >> >> >>> >> >>>>>
> >>>>> >> >> >>> >> >>>>> Assuming you executed "show pool_pools" long after
> >>>>> >> 2020-08-01
> >>>>> >> >> >>> >> >>>>> 06:21:26, that is very strange because
> >>>>> connection_life_time
> >>>>> >> >> >>> should
> >>>>> >> >> >>> >> >>>>> have been already expired. I wonder if pgpool
> tried to
> >>>>> >> >> >>> disconnect the
> >>>>> >> >> >>> >> >>>>> connection but failed. To check what actually
> happend,
> >>>>> can
> >>>>> >> you
> >>>>> >> >> >>> check
> >>>>> >> >> >>> >> >>>>> ps status of pgpool process 18190 and 18193?
> >>>>> >> >> >>> >> >>>>>
> >>>>> >> >> >>> >> >>>>> Also it would be nice you can examine the socket
> status
> >>>>> of
> >>>>> >> >> >>> PostgreSQL
> >>>>> >> >> >>> >> >>>>> backend 29321 and 29619, and pgpool socket status
> of
> >>>>> >> process
> >>>>> >> >> >>> 18190
> >>>>> >> >> >>> >> and
> >>>>> >> >> >>> >> >>>>> 18193?
> >>>>> >> >> >>> >> >>>>>
> >>>>> >> >> >>> >> >>>>> Best regards,
> >>>>> >> >> >>> >> >>>>> --
> >>>>> >> >> >>> >> >>>>> Tatsuo Ishii
> >>>>> >> >> >>> >> >>>>> SRA OSS, Inc. Japan
> >>>>> >> >> >>> >> >>>>> English: http://www.sraoss.co.jp/index_en.php
> >>>>> >> >> >>> >> >>>>> Japanese:http://www.sraoss.co.jp
> >>>>> >> >> >>> >> >>>>>
> >>>>> >> >> >>> >> >>>>
> >>>>> >> >> >>> >> > _______________________________________________
> >>>>> >> >> >>> >> > pgpool-general mailing list
> >>>>> >> >> >>> >> > pgpool-general at pgpool.net
> >>>>> >> >> >>> >> > http://www.pgpool.net/mailman/listinfo/pgpool-general
> >>>>> >> >> >>> >>
> >>>>> >> >> >>>
> >>>>> >> >> >>
> >>>>> >> >>
> >>>>> >>
> >>>>>
> >>> _______________________________________________
> >>> pgpool-general mailing list
> >>> pgpool-general at pgpool.net
> >>> http://www.pgpool.net/mailman/listinfo/pgpool-general
> > _______________________________________________
> > pgpool-general mailing list
> > pgpool-general at pgpool.net
> > http://www.pgpool.net/mailman/listinfo/pgpool-general
>
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