[pgpool-general: 7262] Re: Idle connection in database
Nikhil Shetty
nikhil.dba04 at gmail.com
Thu Sep 3 16:40:50 JST 2020
Hi Tatsuo,
>You need to compare the number before/after serialize_accept is enabled.
>Another point, although not directly related to serialize_accept, you
>must be carefull that pgbench does not eat all CPU resource. If so,
>that could be a bottle neck of the number. In that case, you can run
>multiple pgbench sessions on different machines and sum up the TPS
>number.
Thank you, I will check on this
> 2. Why does load average goes high if serialize_accept is off, is it
> because of the thundering herd problem as mentioned in documentation
>Yes, exactly.
ok.this means we have no choice but to enable serialize_accept.
On Wed, Sep 2, 2020 at 7:27 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> Hi Nikhil,
>
> > Hi Tatsuo,
> >
> > Thank you for the update, I will check and try to do it from my end if
> > possible.
> >
> > I had one last query before closing this, I want to understand when it is
> > advisable to enable serialize_accept. In my case, we are expecting around
> > 1k concurrent connections to the database nad I have gone through
> document "
> >
> https://www.pgpool.net/docs/latest/en/html/runtime-config-connection-pooling.html
> "
> > to run pgbench and check the value for "including connections
> > establishing". I ran the test but i have no idea what value to look for
> > ,below is my test result. I have enabled serialize_accept because when
> > these many connections come to database my pgpool server has a stable
> load
> > average. When serialize_accept is disabled, load average on pgpool server
> > goes beyond 1000 which is not acceptable for production workload
> >
> > [enterprisedb at drplpocppr1 ~]$ pgbench -n -S -h 192.168.16.184 -p 9100 -c
> > 1000 -C -S -T 300 db1
> > Password:
> > transaction type: multiple scripts
> > scaling factor: 10
> > query mode: simple
> > number of clients: 1000
> > number of threads: 1
> > duration: 300 s
> > number of transactions actually processed: 9223
> > latency average = 32534.298 ms
> > tps = 30.736794 (including connections establishing)
> > tps = 30.767516 (excluding connections establishing)
> > SQL script 1: <builtin: select only>
> > - weight: 1 (targets 50.0% of total)
> > - 4598 transactions (49.9% of total, tps = 15.323406)
> > - latency average = 30540.832 ms
> > - latency stddev = 6324.742 ms
> > SQL script 2: <builtin: select only>
> > - weight: 1 (targets 50.0% of total)
> > - 4625 transactions (50.1% of total, tps = 15.413387)
> > - latency average = 30745.421 ms
> > - latency stddev = 5910.625 ms
> >
> > 1. I would like to understand whether " 30.736794 (including connections
> > establishing) " is a good value to enable serialize_accept.
>
> You need to compare the number before/after serialize_accept is enabled.
>
> Another point, although not directly related to serialize_accept, you
> must be carefull that pgbench does not eat all CPU resource. If so,
> that could be a bottle neck of the number. In that case, you can run
> multiple pgbench sessions on different machines and sum up the TPS
> number.
>
> > 2. Why does load average goes high if serialize_accept is off, is it
> > because of the thundering herd problem as mentioned in documentation
>
> Yes, exactly.
>
> > On Tue, Sep 1, 2020 at 10:25 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> >
> >> > Hi Tatsuo,
> >> >
> >> > How do I apply this patch? I have installed pgpool using yum install
> >>
> >> You need to re-create rpm packages. If you are not sure how to do it,
> >> probably you'd better to wait for next rpm releases. (to find release
> >> schedule please visit: https://pgpool.net/mediawiki/index.php/Roadmap)
> >>
> >> > Thanks and Regards,
> >> > Nikhil
> >> >
> >> > On Mon, Aug 31, 2020 at 11:44 AM Nikhil Shetty <
> nikhil.dba04 at gmail.com>
> >> > wrote:
> >> >
> >> >> 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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