<div dir="auto">Hi Tatsuo,<div dir="auto"><br></div><div dir="auto">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.</div><div dir="auto"><br></div><div dir="auto">Thanks for your input Tatsuo, you have been of immense help to find this problem.</div><div dir="auto"><br></div><div dir="auto">Will this fix, when it is done, be included in all 4.0 and 4.1 versions?</div><div dir="auto"><br></div><div dir="auto"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Aug 30, 2020, 14:08 Tatsuo Ishii <<a href="mailto:ishii@sraoss.co.jp">ishii@sraoss.co.jp</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Ok, I found that if following is set:<br>
<br>
serialize_accept=on<br>
<br>
then, connection_life_time does not work. (The alarm is not<br>
fired). Don't know why but I am going to fix this.<br>
<br>
> Hi Tatsuo,<br>
> <br>
> I am using Pgpool v4.1.1.<br>
> <br>
> I have seen similiar behaviour in v4.0.9 as well.<br>
> <br>
> Thanks and Regards,<br>
> Nikhil<br>
> <br>
> On Sun, Aug 30, 2020, 13:11 Tatsuo Ishii <<a href="mailto:ishii@sraoss.co.jp" target="_blank" rel="noreferrer">ishii@sraoss.co.jp</a>> wrote:<br>
> <br>
>> Ok, I have tried with your test data and pgpool settings. Also I added<br>
>> log_disconnections to postgresql.conf so that when Pgpool-II<br>
>> disconnects backend. However I was not able to reproduce your<br>
>> problem. Pgpool-II worked as expected (10 seconds after the test<br>
>> script ends, connection was terminated on all backends).<br>
>><br>
>> What version of Pgpool-II are you using?<br>
>><br>
>> > Hi Tatsuo,<br>
>> ><br>
>> ><br>
>> > No, because my primary has node ID 0 and standby has node ID 1.<br>
>> ><br>
>> > Patch will help if my primary node ID is not 0 rite?<br>
>> ><br>
>> > Thanks and Regards,<br>
>> > Nikhil<br>
>> ><br>
>> ><br>
>> > On Sun, Aug 30, 2020, 12:19 Tatsuo Ishii <<a href="mailto:ishii@sraoss.co.jp" target="_blank" rel="noreferrer">ishii@sraoss.co.jp</a>> wrote:<br>
>> ><br>
>> >> Before these tests, have applied the patch?<br>
>> >><br>
>> >> > Hi Tatsuo,<br>
>> >> ><br>
>> >> ><br>
>> >> > I have to reopen this issue because after a lot of debugging and<br>
>> reading<br>
>> >> > documentation on connection_life_time though there is not much of it,<br>
>> >> this<br>
>> >> > parameter doesn't work as it should.<br>
>> >> ><br>
>> >> > First I want to be correct in my understanding that this parameter<br>
>> >> > terminates cached backend connections in the database.So, I test a<br>
>> simple<br>
>> >> > scenario as follows:<br>
>> >> ><br>
>> >> > PGPOOL - 128.199.224.132<br>
>> >> ><br>
>> >> > *Parameters set for pooling*<br>
>> >> > serialize_accept=on<br>
>> >> > child_life_time=0<br>
>> >> > child_max_connections=0<br>
>> >> > client_idle_limit=0<br>
>> >> > connection_life_time=10<br>
>> >> ><br>
>> >> > *I am running a mixed.sql file which contain below statements*<br>
>> >> > BEGIN;<br>
>> >> > SELECT CURRENT_TIMESTAMP;<br>
>> >> > INSERT into t1 values(3);<br>
>> >> > INSERT into t1 values(4);<br>
>> >> > select pg_sleep(5);<br>
>> >> > INSERT into t1 values(5);<br>
>> >> > UPDATE t1 set id=4 where id=5;<br>
>> >> > END;<br>
>> >> ><br>
>> >> > After executing some inserts it will sleep for 5 seconds and then<br>
>> execute<br>
>> >> > one update and an insert before closing the connection.<br>
>> >> ><br>
>> >> ><br>
>> >> > *1) Status of nodes*<br>
>> >> > -bash-4.2$ psql -h 128.199.224.132 -p 9999 -U enterprisedb<br>
>> >> > psql.bin (11.6.13)<br>
>> >> > Type "help" for help.<br>
>> >> ><br>
>> >> > edb=# show pool_nodes;<br>
>> >> > node_id | hostname | port | status | lb_weight | role |<br>
>> >> > select_cnt | load_balance_node | replication_delay |<br>
>> replication_state |<br>
>> >> > replication_syn<br>
>> >> > c_state | last_status_change<br>
>> >> ><br>
>> >><br>
>> ---------+-----------------+------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+----------------<br>
>> >> > --------+---------------------<br>
>> >> > 0 | 128.199.222.92 | 5445 | up | 0.000000 | primary | 0<br>
>> >> > | false | 0 | |<br>
>> >> > | 2020-08-30 04:58:24<br>
>> >> > 1 | 128.199.222.124 | 5445 | up | 1.000000 | standby | 0<br>
>> >> > | true | 0 | |<br>
>> >> > | 2020-08-30 04:58:24<br>
>> >> > (2 rows)<br>
>> >> ><br>
>> >> > *2) Running the mixed.sql file*<br>
>> >> > -bash-4.2$ psql -h 128.199.224.132 -p 9999 -U enterprisedb -f<br>
>> mixed.sql<br>
>> >> > BEGIN<br>
>> >> > current_timestamp<br>
>> >> > ----------------------------------<br>
>> >> > 30-AUG-20 10:31:47.396527 +05:30<br>
>> >> > (1 row)<br>
>> >> ><br>
>> >> > INSERT 0 1<br>
>> >> > INSERT 0 1<br>
>> >> > pg_sleep<br>
>> >> > ----------<br>
>> >> ><br>
>> >> > (1 row)<br>
>> >> ><br>
>> >> > INSERT 0 1<br>
>> >> > UPDATE 1<br>
>> >> > COMMIT<br>
>> >> > -bash-4.2$<br>
>> >> ><br>
>> >> > *3) pool_pools output shows pgpool (pid - 31560) created one<br>
>> connection<br>
>> >> to<br>
>> >> > master(pid - 31550) and one to standby (pid - 28954) *<br>
>> >> ><br>
>> >> > edb=# show pool_pools;<br>
>> >> > pool_pid | start_time | pool_id | backend_id | database |<br>
>> >> > username | create_time | majorversion | minorversion |<br>
>> >> > pool_counter | pool_<br>
>> >> > backendpid | pool_connected<br>
>> >> ><br>
>> >><br>
>> ----------+---------------------+---------+------------+----------+--------------+---------------------+--------------+--------------+--------------+------<br>
>> >> > -----------+----------------<br>
>> >> > 31560 | 2020-08-30 04:51:54 | 0 | 0 | edb |<br>
>> >> > enterprisedb | 2020-08-30 05:01:47 | 3 | 0 | 1<br>
>> >> > | 31550<br>
>> >> > | 0<br>
>> >> > 31560 | 2020-08-30 04:51:54 | 0 | 1 | edb |<br>
>> >> > enterprisedb | 2020-08-30 05:01:47 | 3 | 0 | 1<br>
>> >> > | 28954<br>
>> >> > | 0<br>
>> >> ><br>
>> >> > *4) Status of process id 31550 on master.After the run, as seen below<br>
>> on<br>
>> >> > the database is idle*<br>
>> >> ><br>
>> >> > -bash-4.2$ ps -ef |grep 224.132<br>
>> >> > enterpr+ 31550 9148 0 05:01 ? 00:00:00 postgres: enterprisedb<br>
>> >> edb<br>
>> >> > 128.199.224.132[49656] idle<br>
>> >> ><br>
>> >> > *5) Status of processid 31560 on pgpool.* *After the run, as seen<br>
>> below<br>
>> >> > pgpool has released connection as soon as transaction completes*<br>
>> >> > [root@pgpool-p pgpool4.1]# ps -ef |grep 31560<br>
>> >> > enterpr+ 31560 31557 0 04:51 ? 00:00:00 pgpool: wait for<br>
>> accept<br>
>> >> lock<br>
>> >> ><br>
>> >> ><br>
>> >> > *6) After 10 seconds, this cached connection on database should have<br>
>> been<br>
>> >> > terminated as per my understanding of connection_life_time parameter<br>
>> but<br>
>> >> as<br>
>> >> > seen below it has not terminated*<br>
>> >> > edb=# select * from pg_stat_activity where client_addr<br>
>> >> ='128.199.224.132';<br>
>> >> > -[ RECORD 1 ]----+---------------------------------<br>
>> >> > datid | 67127<br>
>> >> > datname | edb<br>
>> >> > pid | 31550<br>
>> >> > usesysid | 10<br>
>> >> > usename | enterprisedb<br>
>> >> > application_name | psql.bin<br>
>> >> > client_addr | 128.199.224.132<br>
>> >> > client_hostname |<br>
>> >> > client_port | 49656<br>
>> >> > backend_start | 30-AUG-20 10:31:47.380345 +05:30<br>
>> >> > xact_start |<br>
>> >> > query_start | 30-AUG-20 10:31:52.411607 +05:30<br>
>> >> > state_change | 30-AUG-20 10:31:52.411714 +05:30<br>
>> >> > wait_event_type | Client<br>
>> >> > wait_event | ClientRead<br>
>> >> > state | idle<br>
>> >> > backend_xid |<br>
>> >> > backend_xmin |<br>
>> >> > query | DISCARD ALL<br>
>> >> > backend_type | client backend<br>
>> >> ><br>
>> >> > Do not mind the timestamp, it is in IST for the above query.<br>
>> >> ><br>
>> >> > *7) From the pgpool logs, it sets the alarm after 10 sec but doesn't<br>
>> >> really<br>
>> >> > close the connection after 10 seconds*<br>
>> >> > Aug 30 05:01:52 Pgpool-p pgpool[*31560*]: [252-2] 2020-08-30 05:01:52:<br>
>> >> pid<br>
>> >> > 31560: DETAIL: setting alarm after 10 seconds<br>
>> >> ><br>
>> >> > Attaching pgpool logs as well.<br>
>> >> ><br>
>> >> ><br>
>> >> > On Wed, Aug 12, 2020 at 9:02 PM Nikhil Shetty <<a href="mailto:nikhil.dba04@gmail.com" target="_blank" rel="noreferrer">nikhil.dba04@gmail.com</a><br>
>> ><br>
>> >> > wrote:<br>
>> >> ><br>
>> >> >> Hi Tatsuo,<br>
>> >> >><br>
>> >> >> Thank you, I will check how this works.<br>
>> >> >><br>
>> >> >><br>
>> >> >> On Tue, Aug 11, 2020 at 5:52 PM Tatsuo Ishii <<a href="mailto:ishii@sraoss.co.jp" target="_blank" rel="noreferrer">ishii@sraoss.co.jp</a>><br>
>> >> wrote:<br>
>> >> >><br>
>> >> >>> Hi Nikhil,<br>
>> >> >>><br>
>> >> >>> > Hi Tatsuo,<br>
>> >> >>> ><br>
>> >> >>> > We are checking the patch internally before we go ahead and<br>
>> deploy in<br>
>> >> >>> > production.<br>
>> >> >>><br>
>> >> >>> Ok.<br>
>> >> >>><br>
>> >> >>> > If I want to set only one of either connection_life_time or<br>
>> >> >>> > client_idle_limit. What do you recommend? Should I set<br>
>> >> >>> > client_idle_limit=120 and connection_life_time=0, do you foresee<br>
>> any<br>
>> >> >>> > effects of these settings for connection pooling?<br>
>> >> >>><br>
>> >> >>> In general connection_life_time is better because:<br>
>> >> >>><br>
>> >> >>> 1. when client_idle_limit expires, pgpool needs to fork a new<br>
>> process,<br>
>> >> >>> but connection_life_time does not.<br>
>> >> >>><br>
>> >> >>> 2. when client_idle_limit expires, it looses mutiple connection<br>
>> pools<br>
>> >> >>> (this only applicatable fro max_pool > 1 case) because the<br>
>> >> >>> connection pools the process hold go away.<br>
>> >> >>><br>
>> >> >>> However if you have very short and frequent sessions, more alarm<br>
>> >> >>> system calls with connection_life_time are required and maybe<br>
>> >> >>> client_idle_limit wins in this case.<br>
>> >> >>><br>
>> >> >>> > Thank you for your time and support.<br>
>> >> >>> ><br>
>> >> >>> > Thanks and Regards,<br>
>> >> >>> > Nikhil<br>
>> >> >>> ><br>
>> >> >>> > On Mon, Aug 10, 2020 at 11:58 AM Tatsuo Ishii <<a href="mailto:ishii@sraoss.co.jp" target="_blank" rel="noreferrer">ishii@sraoss.co.jp</a><br>
>> ><br>
>> >> >>> wrote:<br>
>> >> >>> ><br>
>> >> >>> >> Hi Nikhil,<br>
>> >> >>> >><br>
>> >> >>> >> I have been investigating if there's any case when<br>
>> >> >>> >> connection_life_time is not working. Actually it *is*. If primary<br>
>> >> node<br>
>> >> >>> >> is not node 0, connection_life_time does not work. Attached is<br>
>> the<br>
>> >> >>> >> patch to fix that. Please try, if you like.<br>
>> >> >>> >><br>
>> >> >>> >> > According to your previous message, corresponding pgpool<br>
>> process<br>
>> >> was<br>
>> >> >>> >> > not there, but PostgreSQL backend process were still running. I<br>
>> >> >>> >> > suspect the backend process was waiting for TCP/IP connection<br>
>> was<br>
>> >> >>> >> > terminated. But to know what was actually happening, I was<br>
>> waiting<br>
>> >> >>> for<br>
>> >> >>> >> > your response.<br>
>> >> >>> >> ><br>
>> >> >>> >> >>> "DISCARD ALL" and state idle. I will have to test again to<br>
>> check<br>
>> >> >>> the<br>
>> >> >>> >> socket<br>
>> >> >>> >> >>> status of pid.I will get back on this<br>
>> >> >>> >> ><br>
>> >> >>> >> > What was that?<br>
>> >> >>> >> ><br>
>> >> >>> >> >> Hi Tatsuo,<br>
>> >> >>> >> >><br>
>> >> >>> >> >><br>
>> >> >>> >> >> Ant reason why connection_idle_limit doesn't remove backend<br>
>> >> >>> connection<br>
>> >> >>> >> >> after time limit is crossed<br>
>> >> >>> >> >><br>
>> >> >>> >> >> Thanks and Regards,<br>
>> >> >>> >> >> Nikhil<br>
>> >> >>> >> >><br>
>> >> >>> >> >> On Sun, Aug 2, 2020, 12:48 Nikhil Shetty <<br>
>> <a href="mailto:nikhil.dba04@gmail.com" target="_blank" rel="noreferrer">nikhil.dba04@gmail.com</a><br>
>> >> ><br>
>> >> >>> >> wrote:<br>
>> >> >>> >> >><br>
>> >> >>> >> >>> Hi Tatsuo,<br>
>> >> >>> >> >>><br>
>> >> >>> >> >>> I want to correct my statement from previous email:<br>
>> >> >>> >> >>><br>
>> >> >>> >> >>> From ps status *I could not see *that the process (18190 and<br>
>> >> 18193)<br>
>> >> >>> >> were<br>
>> >> >>> >> >>> still present on pgpool but the backend process was still<br>
>> >> present<br>
>> >> >>> with<br>
>> >> >>> >> >>> "DISCARD ALL" and state idle. I will have to test again to<br>
>> check<br>
>> >> >>> the<br>
>> >> >>> >> socket<br>
>> >> >>> >> >>> status of pid.I will get back on this<br>
>> >> >>> >> >>><br>
>> >> >>> >> >>> On Sun, Aug 2, 2020 at 12:15 PM Nikhil Shetty <<br>
>> >> >>> <a href="mailto:nikhil.dba04@gmail.com" target="_blank" rel="noreferrer">nikhil.dba04@gmail.com</a>><br>
>> >> >>> >> >>> wrote:<br>
>> >> >>> >> >>><br>
>> >> >>> >> >>>> Hi Tatsuo,<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> >> Assuming you executed "show pool_pools" long after<br>
>> >> 2020-08-01<br>
>> >> >>> >> >>>> >> 06:21:26, that is very strange because<br>
>> connection_life_time<br>
>> >> >>> should<br>
>> >> >>> >> >>>> >> have been already expired. I wonder if pgpool tried to<br>
>> >> >>> disconnect<br>
>> >> >>> >> the<br>
>> >> >>> >> >>>> >> connection but failed. To check what actually happend,<br>
>> can<br>
>> >> you<br>
>> >> >>> >> check<br>
>> >> >>> >> >>>> >> ps status of pgpool process 18190 and 18193?<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> >> Also it would be nice you can examine the socket status<br>
>> of<br>
>> >> >>> >> PostgreSQL<br>
>> >> >>> >> >>>> >> backend 29321 and 29619, and pgpool socket status of<br>
>> process<br>
>> >> >>> 18190<br>
>> >> >>> >> and<br>
>> >> >>> >> >>>> >> 18193?<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> From ps status I could see that the process (18190 and<br>
>> 18193)<br>
>> >> were<br>
>> >> >>> >> still<br>
>> >> >>> >> >>>> present on pgpool. I will have to test again to check the<br>
>> >> socket<br>
>> >> >>> >> status of<br>
>> >> >>> >> >>>> pid.I will get back on this<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Meanwhile, I did some testing of my own for these two<br>
>> >> parameters(<br>
>> >> >>> >> >>>> client_idle_limit and connection_life_time ) and their<br>
>> >> behaviour:<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *Test:*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Database IP:128.199.222.92(master)<br>
>> >> >>> >> >>>> Pgpool IP: 128.199.224.132<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *Scenario1:*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> max_pool=1<br>
>> >> >>> >> >>>> num_init_children=100<br>
>> >> >>> >> >>>> serialize_accept=on<br>
>> >> >>> >> >>>> child_max_connections=0<br>
>> >> >>> >> >>>> child_life_time=0<br>
>> >> >>> >> >>>> connection_life_time=60<br>
>> >> >>> >> >>>> client_idle_limit=0<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *1. Connected to Pgpool and ran a query with \watch 1:*<br>
>> >> >>> >> >>>> select count(*) from pgbench_accounts ;<br>
>> >> >>> >> >>>> \watch 1<br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:25:54 AM UTC (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> count<br>
>> >> >>> >> >>>> ---------<br>
>> >> >>> >> >>>> 6000000<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *2. Checking session in database, one session is active from<br>
>> >> >>> pgpool*<br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:26:14 AM UTC<br>
>> >> >>> (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename<br>
>> >> |<br>
>> >> >>> >> >>>> client_addr | count | state<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >><br>
>> >> >>><br>
>> >><br>
>> ------+-----------------------------------------+--------------+-----------------+-------+--------<br>
>> >> >>> >> >>>> 3420 | select count(*) from pgbench_accounts ; |<br>
>> enterprisedb<br>
>> >> |<br>
>> >> >>> >> >>>> 128.199.224.132 | 1 | active<br>
>> >> >>> >> >>>> (1 row)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *3. Stopped the query after sometime using Ctrl-C but<br>
>> session<br>
>> >> is<br>
>> >> >>> still<br>
>> >> >>> >> >>>> open*<br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:27:35 AM UTC (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> count<br>
>> >> >>> >> >>>> ---------<br>
>> >> >>> >> >>>> 6000000<br>
>> >> >>> >> >>>> (1 row)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> ^Cedb=#<br>
>> >> >>> >> >>>> edb=#<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *4. Checking session in database, state is now idle*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:28:14 AM UTC<br>
>> >> (every<br>
>> >> >>> 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename<br>
>> >> |<br>
>> >> >>> >> >>>> client_addr | count | state<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >><br>
>> >> >>><br>
>> >><br>
>> ------+-----------------------------------------+--------------+-----------------+-------+-------<br>
>> >> >>> >> >>>> 3420 | select count(*) from pgbench_accounts ; |<br>
>> enterprisedb<br>
>> >> |<br>
>> >> >>> >> >>>> 128.199.224.132 | 1 | idle<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *5. Checking session in database after 2 minutes, I can<br>
>> still<br>
>> >> see<br>
>> >> >>> the<br>
>> >> >>> >> >>>> database session idle*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:30:02 AM UTC<br>
>> >> (every<br>
>> >> >>> 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename<br>
>> >> |<br>
>> >> >>> >> >>>> client_addr | count | state<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >><br>
>> >> >>><br>
>> >><br>
>> ------+-----------------------------------------+--------------+-----------------+-------+-------<br>
>> >> >>> >> >>>> 3420 | select count(*) from pgbench_accounts ; |<br>
>> enterprisedb<br>
>> >> |<br>
>> >> >>> >> >>>> 128.199.224.132 | 1 | idle<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *6. Checking connection on pgpool server. connection is<br>
>> still<br>
>> >> open<br>
>> >> >>> >> from<br>
>> >> >>> >> >>>> pgpool to database*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> ps -ef|grep edb<br>
>> >> >>> >> >>>> enterpr+ 24170 24162 0 06:51 ? 00:00:00 pgpool:<br>
>> >> >>> enterprisedb<br>
>> >> >>> >> edb<br>
>> >> >>> >> >>>> 128.199.222.92(34402) idle<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *7. After being idle for more than 60 seconds, connections<br>
>> are<br>
>> >> >>> still<br>
>> >> >>> >> open<br>
>> >> >>> >> >>>> from pgpool and on database.Connection is removed from<br>
>> pgpool<br>
>> >> >>> server<br>
>> >> >>> >> after<br>
>> >> >>> >> >>>> I quit from the psql terminal but still present in the<br>
>> >> database as<br>
>> >> >>> >> show<br>
>> >> >>> >> >>>> below:*<br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:34:26 AM UTC (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename | client_addr |<br>
>> count |<br>
>> >> >>> state<br>
>> >> >>> >> >>>><br>
>> >> >>><br>
>> ------+--------------+--------------+-----------------+-------+-------<br>
>> >> >>> >> >>>> 3420 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1 |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *Scenario2:*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> max_pool=1<br>
>> >> >>> >> >>>> num_init_children=100<br>
>> >> >>> >> >>>> serialize_accept=on<br>
>> >> >>> >> >>>> child_max_connections=0<br>
>> >> >>> >> >>>> child_life_time=0<br>
>> >> >>> >> >>>> connection_life_time=0<br>
>> >> >>> >> >>>> client_idle_limit=60<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *1. Connected to Pgpool and ran a query with \watch 1:*<br>
>> >> >>> >> >>>> edb=# \! date<br>
>> >> >>> >> >>>> Sat Aug 1 07:38:45 UTC 2020<br>
>> >> >>> >> >>>> select count(*) from pgbench_accounts ;<br>
>> >> >>> >> >>>> \watch 1<br>
>> >> >>> >> >>>> edb=# select count(*) from pgbench_accounts ;<br>
>> >> >>> >> >>>> count<br>
>> >> >>> >> >>>> ---------<br>
>> >> >>> >> >>>> 6000000<br>
>> >> >>> >> >>>> (1 row)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *2. Checking session in database, one session is active from<br>
>> >> >>> pgpool*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:39:55 AM UTC<br>
>> >> >>> (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename<br>
>> >> |<br>
>> >> >>> >> >>>> client_addr | count | state<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >><br>
>> >> >>><br>
>> >><br>
>> -------+-----------------------------------------+--------------+-----------------+-------+--------<br>
>> >> >>> >> >>>> 13427 | select count(*) from pgbench_accounts ; |<br>
>> >> enterprisedb |<br>
>> >> >>> >> >>>> 128.199.224.132 | 1 | active<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *3. Stopped the query after sometime using Ctrl-C but<br>
>> session<br>
>> >> is<br>
>> >> >>> still<br>
>> >> >>> >> >>>> open*<br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:41:39 AM UTC (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> count<br>
>> >> >>> >> >>>> ---------<br>
>> >> >>> >> >>>> 6000000<br>
>> >> >>> >> >>>> ^Cedb=#<br>
>> >> >>> >> >>>> edb=#<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *4. Checking session in database, state is now idle*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:42:12 AM UTC<br>
>> >> >>> (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename<br>
>> >> |<br>
>> >> >>> >> >>>> client_addr | count | state<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >><br>
>> >> >>><br>
>> >><br>
>> -------+-----------------------------------------+--------------+-----------------+-------+-------<br>
>> >> >>> >> >>>> 13427 | select count(*) from pgbench_accounts ; |<br>
>> >> enterprisedb |<br>
>> >> >>> >> >>>> 128.199.224.132 | 1 | idle<br>
>> >> >>> >> >>>> (1 row)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *5. Checking session in database after 2 minutes, there is<br>
>> no<br>
>> >> >>> session<br>
>> >> >>> >> in<br>
>> >> >>> >> >>>> the database.*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Sat 01 Aug 2020 07:42:42 AM UTC (every 1s)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename | client_addr | count | state<br>
>> >> >>> >> >>>> -----+-------+---------+-------------+-------+-------<br>
>> >> >>> >> >>>> (0 rows)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *6. Checking connection on pgpool server. No connection<br>
>> open in<br>
>> >> >>> >> pgpool to<br>
>> >> >>> >> >>>> database*<br>
>> >> >>> >> >>>> ps -ef|grep edb<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> *Observations:*<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> With client_idle_limit of 60 seconds, all connections are<br>
>> >> closed<br>
>> >> >>> after<br>
>> >> >>> >> >>>> being idle for more than 1 minute. I can see psql session in<br>
>> >> >>> database<br>
>> >> >>> >> is<br>
>> >> >>> >> >>>> still present as shown below, because<br>
>> >> >>> >> >>>> I did not quit from psql terminal yet:<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> [root@master ~]# ps -ef |grep 128.199.224.132<br>
>> >> >>> >> >>>> enterpr+ 13193 28563 0 07:38 pts/0 00:00:00 /bin/bash<br>
>> >> >>> /bin/psql -p<br>
>> >> >>> >> >>>> 9999 -h 128.199.224.132<br>
>> >> >>> >> >>>> enterpr+ 13198 13193 0 07:38 pts/0 00:00:00<br>
>> /bin/psql.bin<br>
>> >> -p<br>
>> >> >>> 9999<br>
>> >> >>> >> -h<br>
>> >> >>> >> >>>> 128.199.224.132<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> From scenario 2( client_idle_limit = 60), we can say that<br>
>> when<br>
>> >> >>> >> >>>> client_idle_limit is triggered client is disconnected, no<br>
>> >> database<br>
>> >> >>> >> >>>> connection is in use but the session still remains on<br>
>> >> server.If i<br>
>> >> >>> >> start<br>
>> >> >>> >> >>>> running query<br>
>> >> >>> >> >>>> on same psql session, it will first reset connection and<br>
>> then<br>
>> >> run<br>
>> >> >>> the<br>
>> >> >>> >> >>>> query, this will again create a new connection to the<br>
>> database.<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> From scenario 1(connection_life_time = 60), there is no real<br>
>> >> >>> benefit I<br>
>> >> >>> >> >>>> see. I assumed the connections(DISCARD ALL) present in<br>
>> database<br>
>> >> >>> will<br>
>> >> >>> >> be<br>
>> >> >>> >> >>>> reused but each time I connected to the database, it<br>
>> created a<br>
>> >> new<br>
>> >> >>> >> >>>> connection as seen below:<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> pid | query | usename | client_addr |<br>
>> count<br>
>> >> |<br>
>> >> >>> state<br>
>> >> >>> >> >>>><br>
>> >> >>> >><br>
>> >> -------+--------------+--------------+-----------------+-------+-------<br>
>> >> >>> >> >>>> 12895 | | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 3420 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12531 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12636 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12698 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12751 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12773 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12862 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> 12878 | DISCARD ALL | enterprisedb | 128.199.224.132 |<br>
>> 1<br>
>> >> |<br>
>> >> >>> idle<br>
>> >> >>> >> >>>> (9 rows)<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> Thanks and Regards,<br>
>> >> >>> >> >>>> Nikhil<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>> On Sat, Aug 1, 2020 at 6:45 PM Tatsuo Ishii <<br>
>> >> <a href="mailto:ishii@sraoss.co.jp" target="_blank" rel="noreferrer">ishii@sraoss.co.jp</a>><br>
>> >> >>> >> wrote:<br>
>> >> >>> >> >>>><br>
>> >> >>> >> >>>>> > Hi,<br>
>> >> >>> >> >>>>> ><br>
>> >> >>> >> >>>>> > Yes, we can see the pid<br>
>> >> >>> >> >>>>> ><br>
>> >> >>> >> >>>>> > show pool_pools;<br>
>> >> >>> >> >>>>> > pool_pid | start_time | pool_id | backend_id |<br>
>> >> >>> database |<br>
>> >> >>> >> >>>>> > username | create_time | majorversion |<br>
>> >> minorversion<br>
>> >> >>> |<br>
>> >> >>> >> >>>>> > pool_counter | pool_backendpid | pool_connected<br>
>> >> >>> >> >>>>> ><br>
>> >> >>> >> >>>>> > 18190 | 2020-08-01 06:14:41 | 0 | 1 |<br>
>> edb<br>
>> >> >>> |<br>
>> >> >>> >> >>>>> > enterprisedb | 2020-08-01 06:19:52 | 3 | 0<br>
>> >> >>> |<br>
>> >> >>> >> 1<br>
>> >> >>> >> >>>>> > | *29321* | 0<br>
>> >> >>> >> >>>>> > 18193 | 2020-08-01 06:14:41 | 0 | 1 |<br>
>> edb<br>
>> >> >>> |<br>
>> >> >>> >> >>>>> > enterprisedb | 2020-08-01 06:21:26 | 3 | 0<br>
>> >> >>> |<br>
>> >> >>> >> 1<br>
>> >> >>> >> >>>>> > | *29619 *| 0<br>
>> >> >>> >> >>>>> ><br>
>> >> >>> >> >>>>> ><br>
>> >> >>> >> >>>>> > select pid,query,usename,state from pg_stat_activity<br>
>> where<br>
>> >> >>> >> >>>>> > client_addr='128.199.224.132' group by usename,query,pid;<br>
>> >> >>> >> >>>>> > pid | query | usename | state<br>
>> >> >>> >> >>>>> > -------+--------------+--------------+-------<br>
>> >> >>> >> >>>>> > *29321 *| DISCARD ALL | enterprisedb | idle<br>
>> >> >>> >> >>>>> > *29619* | DISCARD ALL | enterprisedb | idle<br>
>> >> >>> >> >>>>><br>
>> >> >>> >> >>>>> Assuming you executed "show pool_pools" long after<br>
>> 2020-08-01<br>
>> >> >>> >> >>>>> 06:21:26, that is very strange because connection_life_time<br>
>> >> >>> should<br>
>> >> >>> >> >>>>> have been already expired. I wonder if pgpool tried to<br>
>> >> >>> disconnect the<br>
>> >> >>> >> >>>>> connection but failed. To check what actually happend, can<br>
>> you<br>
>> >> >>> check<br>
>> >> >>> >> >>>>> ps status of pgpool process 18190 and 18193?<br>
>> >> >>> >> >>>>><br>
>> >> >>> >> >>>>> Also it would be nice you can examine the socket status of<br>
>> >> >>> PostgreSQL<br>
>> >> >>> >> >>>>> backend 29321 and 29619, and pgpool socket status of<br>
>> process<br>
>> >> >>> 18190<br>
>> >> >>> >> and<br>
>> >> >>> >> >>>>> 18193?<br>
>> >> >>> >> >>>>><br>
>> >> >>> >> >>>>> Best regards,<br>
>> >> >>> >> >>>>> --<br>
>> >> >>> >> >>>>> Tatsuo Ishii<br>
>> >> >>> >> >>>>> SRA OSS, Inc. Japan<br>
>> >> >>> >> >>>>> English: <a href="http://www.sraoss.co.jp/index_en.php" rel="noreferrer noreferrer" target="_blank">http://www.sraoss.co.jp/index_en.php</a><br>
>> >> >>> >> >>>>> Japanese:<a href="http://www.sraoss.co.jp" rel="noreferrer noreferrer" target="_blank">http://www.sraoss.co.jp</a><br>
>> >> >>> >> >>>>><br>
>> >> >>> >> >>>><br>
>> >> >>> >> > _______________________________________________<br>
>> >> >>> >> > pgpool-general mailing list<br>
>> >> >>> >> > <a href="mailto:pgpool-general@pgpool.net" target="_blank" rel="noreferrer">pgpool-general@pgpool.net</a><br>
>> >> >>> >> > <a href="http://www.pgpool.net/mailman/listinfo/pgpool-general" rel="noreferrer noreferrer" target="_blank">http://www.pgpool.net/mailman/listinfo/pgpool-general</a><br>
>> >> >>> >><br>
>> >> >>><br>
>> >> >><br>
>> >><br>
>><br>
</blockquote></div>