FATAL: could not read pid file

  Error:- I faced this issue when I first time installed the edb-pgpool42.  Installed the PGPOOL4.2 and started the pgpool service successfully. But after reboot the pgpool server, it not came up. Error reported in PGPOOL log file  was  "FATAL:  could not read pid file".

Issue:-

Error report in edb-pgpool42.log log file

root@ip:/var/run/runfile# cd /var/log/edb/pgpool4.2/

root@ip:/var/log/edb/pgpool4.2# ls -lrth

total 4.0K

-rw-r--r-- 1 enterprisedb enterprisedb 202 Dec 25 12:39 edb-pgpool42.log

root@ip:/var/log/edb/pgpool4.2# cat edb-pgpool42.log

2021-12-25 12:39:25: pid 8228: WARNING:  "pool_conn_dbname" is depreciated, use "health_check_database" to configure health check database

2021-12-25 12:39:25: pid 8228: FATAL:  could not read pid file

root@ip:/var/log/edb/pgpool4.2#

Solution:-

1. Checked the /etc/edb/edb-pgpool42/pgpool.conf file. Check the location of pid_file_name.

pid_file_name = '/var/run/edb/pgpool4.2/edb-pgpool-4.2.pid'

2. Change the directory of pid_file_name in pgpool.conf file and take the restart/start.

ex: pid_file_name = '/var/run/any_directory/pgpool.pid'

pid_file_name = '/var/run/anylocation/edb-pgpool-4.2.pid'

3. Give full permission to enterprisedb or postgres

root@ip:/var/run# pwd

/var/run

drwxr-xr-x  2 enterprisedb enterprisedb   80 Dec 25 15:25 anylocation

root@ip:/var/run# cd anylocation

root@ip:/var/run# ls

-rw------- 1 enterprisedb enterprisedb 6 Dec 25 15:20 edb-pgpool-4.2.pid

4. Check all the directory mentioned in pgpool.conf file exists or not and having proper permission. In my case directory /var/run/edb-as/ was missing.  

enterprisedb@ip:~$ /usr/edb/pgpool4.2/bin/pgpool -n -d

pid 28631: WARNING:  "pool_conn_dbname" is depreciated, use "health_check_database" to configure health check database

pid 28631: DEBUG:  initializing pool configuration

pid 28631: DETAIL:  num_backends: 1 total_weight: 1.000000

pid 28631: DEBUG:  initializing pool configuration

pid 28631: DETAIL:  backend 0 weight: 2147483647.000000 flag: 0000

pid 28631: DEBUG:  pool_coninfo_size: num_init_children (32) * max_pool (4) * MAX_NUM_BACKENDS (128) * sizeof(ConnectionInfo) (136) = 2228224 bytes requested for shared memory

pid 28631: LOG:  health_check_stats_shared_memory_size: requested size: 12288

pid 28631: LOG:  memory cache initialized

pid 28631: DETAIL:  memcache blocks :64

pid 28631: LOG:  allocating (136571712) bytes of shared memory segment

pid 28631: LOG:  allocating shared memory segment of size: 136571712

pid 28631: DEBUG:  pool_coninfo_size: num_init_children (32) * max_pool (4) * MAX_NUM_BACKENDS (128) * sizeof(ConnectionInfo) (136) = 2228224 bytes requested for shared memory

pid 28631: LOG:  health_check_stats_shared_memory_size: requested size: 12288

pid 28631: LOG:  health_check_stats_shared_memory_size: requested size: 12288

pid 28631: LOG:  memory cache initialized

pid 28631: DETAIL:  memcache blocks :64

pid 28631: DEBUG:  memory cache request size : 67108864

pid 28631: LOG:  pool_discard_oid_maps: discarded memqcache oid maps

pid 28631: FATAL:  failed to bind a socket: "/var/run/edb-as/.s.PGSQL.9999"

pid 28631: DETAIL:  bind socket failed with error: "No such file or directory"

pid 28631: LOG:  shutting down

4. Created the missed directory and verify the other directories too.

enterprisedb@ip:~$ cd /var/run/edb-as/

-bash: cd: /var/run/edb-as/: No such file or directory

root@ip:/tmp# mkdir -p /var/run/edb-as/

root@ip:/tmp# chown enterprisedb:enterprisedb /var/run/edb-as/

root@ip:/tmp# su - enterprisedb

5. Started the service successfully.

root@ip:/tmp# systemctl start edb-pgpool42.service

root@ip:/tmp# systemctl status edb-pgpool42.service

● edb-pgpool42.service - pgpool-II service script for EDB Postgres Advanced Server

     Loaded: loaded (/lib/systemd/system/edb-pgpool42.service; enabled; vendor preset: enabled)

     Active: active (running) since Sat 2021-12-25 15:20:33 UTC; 2s ago

    Process: 29671 ExecStart=/bin/bash -c /usr/edb/pgpool4.2/bin/edb-pgpool42.sh (code=exited, status=0/SUCCESS)

   Main PID: 29672 (pgpool)

      Tasks: 33 (limit: 1147)

     Memory: 143.5M

     CGroup: /system.slice/edb-pgpool42.service

             ├─29672 /usr/edb/pgpool4.2/bin/pgpool -D -f /etc/edb/edb-pgpool42/pgpool.conf -n -F /etc/edb/edb-pgpool42/pcp.conf>

             ├─29676 pgpool: wait for connection request

             ├─29677 pgpool: wait for connection request

             ├─29678 pgpool: wait for connection request

             ├─29679 pgpool: wait for connection request

             ├─29680 pgpool: wait for connection request

             ├─29681 pgpool: wait for connection request

             ├─29682 pgpool: wait for connection request

             ├─29683 pgpool: wait for connection request

             ├─29684 pgpool: wait for connection request

             ├─29685 pgpool: wait for connection request

             ├─29686 pgpool: wait for connection request

             ├─29687 pgpool: wait for connection request

             ├─29688 pgpool: wait for connection request

             ├─29689 pgpool: wait for connection request