[pgpool-general: 9497] Re: Weird error in pgpool 4.6 logs: WARNING: failed to lock semaphore
Tatsuo Ishii
ishii at postgresql.org
Mon Jun 2 20:42:40 JST 2025
> Hi, another thing I noticed - the status of all those nodes in
> pcp_node_info seems to be wrong, for example:
> $ pcp_node_info -h localhost -p 9898 -U pcpadmin --verbose -n 3
> Hostname : db-replica2
> Port : 5434
> Status : 1
> Weight : 0.250000
> Status Name : waiting
> Backend Status Name : up
> Role : standby
> Backend Role : standby
> Replication Delay : 0
> Replication State : streaming
> Replication Sync State : async
> Last Status Change : 2025-06-02 12:31:46
Are you saying this is wrong?
> Status : 1
Seems normal to me because it just says no client has connected to the
pgpool server until now.
> Do you think this is because of the semaphore problem, or does it suggest
> something else completely?
>
> On Mon, Jun 2, 2025 at 12:59 PM Tatsuo Ishii <ishii at postgresql.org> wrote:
>
>> > Hi, I changed the pgpool.service file for startup as you said, replaced
>> my
>> > start with this:
>> > ExecStart=strace -f -tt --trace=ipc /usr/sbin/pgpool -f
>> > /etc/pgpool2/pgpool.conf $OPTS
>> > I'm attaching the log from replica again, but I'm not sure this actually
>> > worked (as in, it doesn't look much different, to me at least).
>>
>> Yeah. It seems there's strace output in the log.
>> Can you try "-o" of strace, which instructs strace a file name to print
>> the output. e.g.
>>
>> ExecStart=strace -f -tt --trace=ipc -o /tmp/strace.out /usr/sbin/pgpool -f
>> /etc/pgpool2/pgpool.conf $OPTS
>>
>> > On Mon, Jun 2, 2025 at 11:47 AM Tatsuo Ishii <ishii at postgresql.org>
>> wrote:
>> >
>> >> > Hi,
>> >> > I tried the strace as you shown but it didn't really output anything:
>> >> >
>> >> > $ sudo strace -p 1662563 -f -tt --trace=ipc
>> >> > strace: Process 1662563 attached
>> >> >
>> >> > ^Cstrace: Process 1662563 detached. <--- this is me getting out of
>> it,
>> >> > since I saw in another window the semaphores were gone already,
>> without
>> >> > anything outputting here. Unless something's wrong with the syntax of
>> >> the
>> >> > command, it didn't really output anything. I changed the log line you
>> >> > suggested as well.
>> >> >
>> >> > Also, FYI - I tried to downgrade to a lower (4.3.7) version as it was
>> >> > available in my package repository, and the same semaphore version
>> >> persists,
>> >>
>> >> Okay. I think you need to start pgpool from strace. I mean, modifiy
>> >> pgpool.service from:
>> >> ExecStart=/usr/sbin/pgpool -f /etc/pgpool2/pgpool.conf $OPTS
>> >> to:
>> >> ExecStart=strace -f -tt --trace=ipc /usr/sbin/pgpool -f
>> >> /etc/pgpool2/pgpool.conf $OPTS
>> >>
>> >> > On Mon, Jun 2, 2025 at 2:40 AM Tatsuo Ishii <ishii at postgresql.org>
>> >> wrote:
>> >> >
>> >> >> > Hi,
>> >> >> > Not sure I can patch the source, as it was installed via apt get
>> and
>> >> not
>> >> >> > compiled from source. If that is doable to a package-built one and
>> >> you
>> >> >> can
>> >> >> > give me some instructions, I can certainly try.
>> >> >>
>> >> >> Unfortunately I'm not familiar with debian packaging.
>> >> >>
>> >> >> > As for the pgpool log, I'm attaching it, hopefully it will go
>> through,
>> >> >> it's
>> >> >> > about 5mb as I enabled higher debug options.
>> >> >>
>> >> >> It was sent as a direct mail to me. Not sure who/what removed the
>> >> >> semaphore. I observe following from the log anyway:
>> >> >>
>> >> >> - pgpool started on 16:10:21. At that time the semaphore definitely
>> >> >> existed.
>> >> >> - Until 16:15:13, everything worked great.
>> >> >> - On 16:15:23, the problem started.
>> >> >>
>> >> >> So it seems the semaphore was removed by someone between 16:15:13 and
>> >> >> 16:15:23.
>> >> >>
>> >> >> Unfortunately the removal of semaphore was not recorded in the log.
>> To
>> >> >> determine who removed the semaphore, can you please attach strace to
>> >> >> pgpool main and share the log? This time debug log is not necessary.
>> >> >>
>> >> >> - Find the pgpool parent process pid (in the debug log it was
>> 1483510)
>> >> >> - Become root (attaching strace usually requires root privilege)
>> >> >> - Attach strace to the process $pid
>> >> >>
>> >> >> strace -p $pid -f -tt --trace=ipc
>> >> >>
>> >> >> -f: (follow the child process of pgpool main)
>> >> >> -tt: add timestamp with milliseconds
>> >> >> --trace=ipc: limit the tracing system call to ipc to reduce the log
>> >> >>
>> >> >> BTW, I recommend yo to set log_line_prefix to something like this so
>> >> >> that you can take milliseconds log (%m) and process application name
>> >> >> (%a). They are usable in 4.6.
>> >> >>
>> >> >> log_line_prefix = '%m: %a pid %p: '
>> >> >>
>> >> >> > On Sun, Jun 1, 2025 at 4:20 PM Tatsuo Ishii <ishii at postgresql.org>
>> >> >> wrote:
>> >> >> >
>> >> >> >> > To your points/questions:
>> >> >> >> > 1) version is 4.6.1 - the source I'm using (via apt get) doesn't
>> >> have
>> >> >> >> 4.6.2
>> >> >> >> > yet
>> >> >> >>
>> >> >> >> Ok.
>> >> >> >>
>> >> >> >> > 2) ipcs -s shows... nothing, literally. Checked all nodes, i.e.
>> >> >> >> >
>> >> >> >> > postgres at db-replica3:~$ ipcs -s
>> >> >> >> >
>> >> >> >> > ------ Semaphore Arrays --------
>> >> >> >> > key semid owner perms nsems
>> >> >> >> >
>> >> >> >> > Also, it kinda seems like "failed to unlock semaphore" shows
>> during
>> >> >> >> startup
>> >> >> >> > of pgpool and while it's running, but maybe I'm not reading the
>> log
>> >> >> >> > properly.
>> >> >> >>
>> >> >> >> So pgpool lost semaphore soon after starting. Can you share full
>> >> >> >> pgpool log before "failed to unlock semaphore" appears?
>> >> >> >>
>> >> >> >> > 3) regarding heartbeats, my pgpool.conf has it roughly like
>> this:
>> >> >> >> >
>> >> >> >> > heartbeat_hostname0 = 'db-primary-priv'
>> >> >> >> > heartbeat_port0 = 9694
>> >> >> >> > heartbeat_device0 = ''
>> >> >> >> >
>> >> >> >> > heartbeat_hostname1 = 'db-replica1-priv'
>> >> >> >> > heartbeat_port1 = 9694
>> >> >> >> > heartbeat_device1 = ''
>> >> >> >> >
>> >> >> >> > heartbeat_hostname2 = 'db-replica2-priv'
>> >> >> >> > heartbeat_port2 = 9694
>> >> >> >> > heartbeat_device2 = ''
>> >> >> >> >
>> >> >> >> > heartbeat_hostname3 = 'db-replica3-priv'
>> >> >> >> > heartbeat_port3 = 9694
>> >> >> >> > heartbeat_device3 = ''
>> >> >> >>
>> >> >> >> Looks normal.
>> >> >> >>
>> >> >> >> I have checked the pgpool source code and found suspicious
>> >> >> >> code. before 4.6, pgpool heartbeart receiver process binds to any
>> >> >> >> address on the host. However from 4.6 pgpool binds to only loop
>> back
>> >> >> >> address, which is plain wrong. Is it possible for you to patch the
>> >> >> >> pgpool source code and build pgpool binary?
>> >> >> >>
>> >> >> >> > So it seems likely that the inability to lock/unlock semaphores
>> is
>> >> the
>> >> >> >> > problem, question is why and how do I resolve it? :(
>> >> >> >>
>> >> >> >> Currently I have no idea. That's why I am requesting the pgpool
>> log.
>> >> >> >>
>> >> >> >> > I'll c/p parts of my pgpool.service file as well, in case you
>> may
>> >> see
>> >> >> >> > something 'off' in it?
>> >> >> >> >
>> >> >> >> >
>> >> >> >> > [Service]
>> >> >> >> > User=postgres
>> >> >> >> > Group=postgres
>> >> >> >> >
>> >> >> >> > EnvironmentFile=-/etc/default/pgpool2
>> >> >> >> >
>> >> >> >> > ExecStart=/usr/sbin/pgpool -f /etc/pgpool2/pgpool.conf $OPTS
>> >> >> >> > ExecStop=/usr/sbin/pgpool -f /etc/pgpool2/pgpool.conf $STOP_OPTS
>> >> stop
>> >> >> >> > ExecReload=/usr/sbin/pgpool -f /etc/pgpool2/pgpool.conf reload
>> >> >> >> > LimitNOFILE=65536:65536
>> >> >> >> > LimitNPROC=16384:16384
>> >> >> >> > LimitSTACK=10485760:33554432
>> >> >> >> > LimitMEMLOCK=infinity
>> >> >> >> > LimitDATA=infinity
>> >> >> >> >
>> >> >> >> >
>> >> >> >> > Thanks in advance.
>> >> >> >> >
>> >> >> >> > On Sun, Jun 1, 2025 at 2:06 PM Tatsuo Ishii <
>> ishii at postgresql.org>
>> >> >> >> wrote:
>> >> >> >> >
>> >> >> >> >> > Hi,
>> >> >> >> >> > So long story short, I'm migrating a PG13 cluster from RHEL
>> to
>> >> >> Ubuntu
>> >> >> >> >> > 24.04. In the process, the pgpool version is also being
>> >> upgraded to
>> >> >> >> 4.6
>> >> >> >> >> > (from 4.2).
>> >> >> >> >>
>> >> >> >> >> What is the exact version of 4.6? I am asking because 4.6.0 has
>> >> >> >> >> vulnerability.
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >>
>> >> >>
>> >>
>> https://pgpool.net/mediawiki/index.php/Main_Page#Pgpool-II_4.6.1.2C_4.5.7.2C_4.4.12.2C_4.3.15_and_4.2.22_officially_released_.282025.2F05.2F15.29
>> >> >> >> >>
>> >> >> >> >> Also 4.6.1 (and 4.6.0) have an issue with IPv6.
>> >> >> >> >> https://www.pgpool.net/docs/latest/en/html/release-4-6-2.html
>> >> >> >> >>
>> >> >> >> >> If possible, I recommend to upgrade to 4.6.2.
>> >> >> >> >>
>> >> >> >> >> > There is also repmgr running on this 4 node cluster, 1
>> primary
>> >> >> >> >> > and 3 replicas.
>> >> >> >> >>
>> >> >> >> >> I am not famililar with repmgr, and I ignore this part.
>> >> >> >> >>
>> >> >> >> >> > All the migration seems to have completed successfully,
>> >> >> >> >> > but I've ran into a weird problem with pgpool. I have quite
>> a
>> >> few
>> >> >> >> errors
>> >> >> >> >> > that look like the below entries, and it seems to "come and
>> go"
>> >> >> when
>> >> >> >> >> > checking pgpool log. The process itself, seems to work (I
>> >> think),
>> >> >> but
>> >> >> >> >> > every now and then, these errors (warnings?) show up:
>> >> >> >> >> >
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628043: DEBUG: watchdog heartbeat:
>> >> send
>> >> >> >> >> heartbeat
>> >> >> >> >> > signal to db-replica3-priv:9694
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628043: LOCATION:
>> wd_heartbeat.c:771
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOG: exit handler called
>> >> >> (signal: 2)
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOCATION:
>> pgpool_main.c:1272
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> > *2025-06-01 09:11:00: pid 627958: WARNING: failed to lock
>> >> >> >> >> > semaphore2025-06-01 09:11:00: pid 627958: DETAIL: Invalid
>> >> >> >> >> argument*2025-06-01
>> >> >> >> >> > 09:11:00: pid 627958: LOCATION: pool_sema.c:129
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: WARNING: failed to unlock
>> >> >> semaphore
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: DETAIL: Invalid argument
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOCATION: pool_sema.c:202
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOG: shutting down by
>> signal 2
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOCATION:
>> pgpool_main.c:1324
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOG: terminating all child
>> >> >> processes
>> >> >> >> >> > 2025-06-01 09:11:00: pid 627958: LOCATION:
>> pgpool_main.c:1334
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628047: WARNING: failed to lock
>> >> semaphore
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628047: DETAIL: Invalid argument
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628047: LOCATION: pool_sema.c:129
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628042: WARNING: failed to lock
>> >> semaphore
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628042: DETAIL: Invalid argument
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628042: LOCATION: pool_sema.c:129
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628039: WARNING: failed to lock
>> >> semaphore
>> >> >> >> >> > 2025-06-01 09:11:00: pid 628039: DETAIL: Invalid argument
>> >> >> >> >>
>> >> >> >> >> Can you share the result of "ipcs -s" so that I can confirm
>> pgpool
>> >> >> >> >> properly allocates the semaphore.
>> >> >> >> >>
>> >> >> >> >> By the way do you see "WARNING: failed to unlock semaphore"
>> only
>> >> when
>> >> >> >> >> pgpool is shutting down?
>> >> >> >> >>
>> >> >> >> >> > Also, earlier in the log, I see errors about being unable to
>> >> >> create a
>> >> >> >> >> > socket, for some reason it's trying (and failing) to create
>> >> socket
>> >> >> on
>> >> >> >> >> > localhost (127.0.0.1:9694) and "creating socket on
>> ::1:9694".
>> >> >> Are
>> >> >> >> >> these
>> >> >> >> >> > "ok to ignore"?
>> >> >> >> >>
>> >> >> >> >> First of all "creating socket on ::1:9694" looks unusual
>> because
>> >> it
>> >> >> >> >> means that heartbeat_hostname is set to "::1", which is the
>> IPv6
>> >> loop
>> >> >> >> >> back address. heartbeat_hostname is expected to be set IPv4 or
>> >> IPv6
>> >> >> >> >> inet addesss (not loop back address).
>> >> >> >> >>
>> >> >> >> >> For now, I would like to wait for your reply regarding these my
>> >> >> >> >> questions above.
>> >> >> >> >>
>> >> >> >> >> Best regards,
>> >> >> >> >> --
>> >> >> >> >> Tatsuo Ishii
>> >> >> >> >> SRA OSS K.K.
>> >> >> >> >> English: http://www.sraoss.co.jp/index_en/
>> >> >> >> >> Japanese:http://www.sraoss.co.jp
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: DETAIL: creating socket on
>> >> >> >> >> 127.0.0.1:9694
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOCATION:
>> wd_heartbeat.c:385
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOG: set SO_REUSEPORT
>> option
>> >> to
>> >> >> the
>> >> >> >> >> socket
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOCATION:
>> wd_heartbeat.c:891
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOG: creating watchdog
>> >> heartbeat
>> >> >> >> >> receive
>> >> >> >> >> > socket.
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: DETAIL: creating socket on
>> >> >> ::1:9694
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOCATION:
>> wd_heartbeat.c:385
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOG: failed to create
>> watchdog
>> >> >> >> >> heartbeat
>> >> >> >> >> > receive socket. retrying...
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: DETAIL: bind failed with
>> >> reason:
>> >> >> >> >> "Cannot
>> >> >> >> >> > assign requested address"
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634772: LOCATION:
>> wd_heartbeat.c:394
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: DEBUG:
>> >> >> verify_backend_node_status:
>> >> >> >> >> > true_primary 0
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: LOCATION:
>> pgpool_main.c:2704
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: DEBUG: node status[0]: 1
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: LOCATION:
>> >> pool_worker_child.c:267
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: DEBUG: node status[1]: 2
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: LOCATION:
>> >> pool_worker_child.c:267
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: DEBUG: node status[2]: 2
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: LOCATION:
>> >> pool_worker_child.c:267
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: DEBUG: node status[3]: 2
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: LOCATION:
>> >> pool_worker_child.c:267
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: DEBUG:
>> >> >> >> pool_release_follow_primary_lock
>> >> >> >> >> > called
>> >> >> >> >> > 2025-06-01 09:11:22: pid 635274: LOCATION:
>> pgpool_main.c:4106
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOG: set SO_REUSEPORT
>> option
>> >> to
>> >> >> the
>> >> >> >> >> socket
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOCATION:
>> wd_heartbeat.c:891
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOG: creating watchdog
>> >> heartbeat
>> >> >> >> >> receive
>> >> >> >> >> > socket.
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: DETAIL: creating socket on
>> >> >> >> >> 127.0.0.1:9694
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOCATION:
>> wd_heartbeat.c:385
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOG: set SO_REUSEPORT
>> option
>> >> to
>> >> >> the
>> >> >> >> >> socket
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOCATION:
>> wd_heartbeat.c:891
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOG: creating watchdog
>> >> heartbeat
>> >> >> >> >> receive
>> >> >> >> >> > socket.
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> > *2025-06-01 09:11:23: pid 634765: DETAIL: creating socket on
>> >> >> >> >> > ::1:96942025-06-01 09:11:23: pid 634765: LOCATION:
>> >> >> >> >> > wd_heartbeat.c:3852025-06-01 09:11:23: pid 634765: LOG:
>> >> failed to
>> >> >> >> >> create
>> >> >> >> >> > watchdog heartbeat receive socket. retrying...*2025-06-01
>> >> 09:11:23:
>> >> >> >> pid
>> >> >> >> >> > 634765: DETAIL: bind failed with reason: "Cannot assign
>> >> requested
>> >> >> >> >> address"
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634765: LOCATION:
>> wd_heartbeat.c:394
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634767: LOG: set SO_REUSEPORT
>> option
>> >> to
>> >> >> the
>> >> >> >> >> socket
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634767: LOCATION:
>> wd_heartbeat.c:891
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634767: LOG: creating socket for
>> >> sending
>> >> >> >> >> heartbeat
>> >> >> >> >> > 2025-06-01 09:11:23: pid 634767: DETAIL: set SO_REUSEPORT
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> > Other odd errors I see in the logs later on are when pgpool
>> >> tries
>> >> >> to
>> >> >> >> run
>> >> >> >> >> > escalation script - can't quite find where it's failing to
>> find
>> >> >> ipv4
>> >> >> >> >> > address:
>> >> >> >> >> >
>> >> >> >> >> > 2025-06-01 00:07:15: pid 395780: LOG: Pgpool-II parent
>> process
>> >> >> >> received
>> >> >> >> >> > SIGUSR1
>> >> >> >> >> > 2025-06-01 00:07:15: pid 395780: LOG: Pgpool-II parent
>> process
>> >> >> >> received
>> >> >> >> >> > watchdog quorum change signal from watchdog
>> >> >> >> >> > 2025-06-01 00:07:15: pid 396973: LOG: watchdog: escalation
>> >> started
>> >> >> >> >> > 2025-06-01 00:07:15: pid 395786: LOG: Setting failover
>> command
>> >> >> >> timeout
>> >> >> >> >> to
>> >> >> >> >> > 135
>> >> >> >> >> > 2025-06-01 00:07:15: pid 395780: LOG: watchdog cluster now
>> >> holds
>> >> >> the
>> >> >> >> >> quorum
>> >> >> >> >> > 2025-06-01 00:07:15: pid 395780: DETAIL: updating the state
>> of
>> >> >> >> >> quarantine
>> >> >> >> >> > backend nodes
>> >> >> >> >> > Sun Jun 1 12:07:15 AM CEST 2025
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> >
>> >> >> >> >> > *escalation.sh: - remove VIP IP from all nodesNode:
>> >> >> >> db-primary-privError:
>> >> >> >> >> > ipv4: Address not found.Node: db-replica1-privError: ipv4:
>> >> Address
>> >> >> not
>> >> >> >> >> > found.Node: db-replica2-privError: ipv4: Address not
>> found.Node:
>> >> >> >> >> > db-replica3-privError: ipv4: Address not found.*2025-06-01
>> >> >> 00:07:20:
>> >> >> >> pid
>> >> >> >> >> > 396973: LOG: watchdog escalation successful
>> >> >> >> >> > 2025-06-01 00:07:23: pid 396973: LOG: successfully acquired
>> the
>> >> >> >> delegate
>> >> >> >> >> > IP:"192.168.77.130"
>> >> >> >> >> > 2025-06-01 00:07:23: pid 396973: DETAIL: 'if_up_cmd'
>> returned
>> >> with
>> >> >> >> >> success
>> >> >> >> >> > 2025-06-01 00:07:23: pid 395786: LOG: watchdog escalation
>> >> process
>> >> >> >> with
>> >> >> >> >> > pid: 396973 exit with SUCCESS.
>> >> >> >> >> > 2025-06-01 00:07:27: pid 395962: WARNING: failed to lock
>> >> semaphore
>> >> >> >> >> > 2025-06-01 00:07:27: pid 395962: DETAIL: Invalid argument
>> >> >> >> >> > 2025-06-01 00:07:27: pid 395962: WARNING: failed to unlock
>> >> >> semaphore
>> >> >> >> >> > 2025-06-01 00:07:27: pid 395962: DETAIL: Invalid argument
>> >> >> >> >> > 2025-06-01 00:07:28: pid 396924: WARNING: failed to lock
>> >> semaphore
>> >> >> >> >> > 2025-06-01 00:07:28: pid 396924: DETAIL: Invalid argument
>> >> >> >> >> >
>> >> >> >> >> > The way I started was I copied pgpool.conf from the "old" and
>> >> >> working
>> >> >> >> >> > pgpool 4.2 configuration and modified it slightly, though
>> >> nothing
>> >> >> >> >> > major,changed hostnames and i.e. delegate_ip variable name
>> was
>> >> >> changed
>> >> >> >> >> > from delegate_IP. Also added this variable as without it, I
>> >> didn't
>> >> >> >> see a
>> >> >> >> >> > socket created for port 9898:
>> >> >> >> >> > unix_socket_directories = '/var/run/postgresql'
>> >> >> >> >> > I had to change network interfaces as well, in the RHEL it
>> was
>> >> >> using
>> >> >> >> eth0
>> >> >> >> >> > where on Ubuntu it's ens18, so I changed lines like:
>> >> >> >> >> > /usr/bin/sudo /sbin/ip addr add $_IP_$/23 dev ens18 label
>> >> ens18:0
>> >> >> >> >> > Other thing I had to change was path to arping as on Ubuntu
>> 24
>> >> >> it's in
>> >> >> >> >> > /usr/bin (not sbin)
>> >> >> >> >> > arping_cmd = '/usr/bin/sudo /usr/bin/arping -U $_IP_$ -w 1
>> -I
>> >> >> ens18'
>> >> >> >> >> >
>> >> >> >> >> > The other thing I'm confused about, I have two network
>> >> interfaces
>> >> >> on
>> >> >> >> each
>> >> >> >> >> > host, i.e.
>> >> >> >> >> > 192.168.77.135/23 brd 192.168.77.255 scope global ens18
>> >> >> >> >> > and
>> >> >> >> >> > inet 192.168.78.135/24 brd 192.168.78.255 scope global ens19
>> >> >> >> >> >
>> >> >> >> >> > In pgpool.conf, it is referencing the "priv" hosts (i.e.
>> >> >> >> >> > heartbeat_hostname2 = 'db-replica2-priv'), which
>> theoretically
>> >> >> should
>> >> >> >> be
>> >> >> >> >> on
>> >> >> >> >> > ens19 network interface as shown above, but in my old
>> >> pgpool.conf,
>> >> >> it
>> >> >> >> was
>> >> >> >> >> > only referencing eth0 on RHEL, even though "priv" hosts were
>> on
>> >> >> eth1.
>> >> >> >> >> I'm
>> >> >> >> >> > wondering if that needs to be changed in Ubuntu or it makes
>> no
>> >> >> >> difference
>> >> >> >> >> > here?
>> >> >> >> >> >
>> >> >> >> >> > Right now, I can't quite figure out whether it is something
>> >> with
>> >> >> >> >> > pgpool.conf or with the Ubuntu settings and the semaphore
>> error
>> >> is
>> >> >> >> quite
>> >> >> >> >> > cryptic. If you need me to post some parts of my
>> pgpool.conf,
>> >> >> please
>> >> >> >> >> > advise which. I've seen an older version of the FAQ that
>> said
>> >> >> repmgr
>> >> >> >> and
>> >> >> >> >> > pgpool don't work together but then I saw mention that this
>> was
>> >> no
>> >> >> >> longer
>> >> >> >> >> > the case.
>> >> >> >> >> >
>> >> >> >> >> > I would much appreciate any help you can provide in solving
>> this
>> >> >> >> problem.
>> >> >> >> >>
>> >> >> >>
>> >> >>
>> >>
>>
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