Hi all,
We are encountering a concurrency issue with pg_ctl in PostgreSQL 15.12, two separate processes are invoking pg_ctl simultaneously on different databases directories:
- One process is attempting to stop a database.
- Another process is concurrently executing pg_ctl status to check the PG server state.
Below are the running pg_ctl processes. Here to mention both the DB directories are entirely different.
pgadmin 25559346 26870100 0 Aug 28 - 0:00 -ksh -c pg_ctl status -D /pgmount/PG/DB/
pgadmin 25690410 27591028 0 Aug 28 - 0:00 -ksh -c pg_ctl stop -D /pgmount/MS/DB/
This concurrent usage results in both processes hanging indefinitely.
Below are the stacks of both the processes
# dbx -a 25559346
Waiting to attach to process 25559346 ...
Successfully attached to ksh.
warning: Directory containing ksh could not be determined.
Apply ‘use’ command to initialize source path.Type ‘help’ for help.
reading symbolic information ...warning: no source compiled with -gstopped in pause at 0xd01b7104
0xd01b7104 (pause+0x204) 80410014 lwz r2,0x14(r1)
(dbx) t
pause() at 0xd01b7104
IPRA.(??, ??, ??, ??, ??) at 0x100387f4
sh_exec(??, ??, ??) at 0x1003a120
IPRA.(??) at 0x10009328
IPRA.(??) at 0x1000a98c
copyto(??, ??, ??) at 0x1000af0c
mac_expand(??) at 0x1000b960
mac_trim(??, ??) at 0x1000b5dc
env_setlist(??, ??) at 0x10022034
IPRA.(??, ??, ??, ??, ??) at 0x10038c90
sh_exec(??, ??, ??) at 0x1003a120
IPRA.() at 0x10001b48
main(??, ??) at 0x10000e3c
# dbx -a 25690410
Waiting to attach to process 25690410 ...
Successfully attached to ksh.
warning: Directory containing ksh could not be determined.
Apply ‘use’ command to initialize source path.Type ‘help’ for help.
reading symbolic information ...warning: no source compiled with -gstopped in pause at 0xd01b7104
0xd01b7104 (pause+0x204) 80410014 lwz r2,0x14(r1)
(dbx) th
(dbx) t
pause() at 0xd01b7104
IPRA.(??, ??, ??, ??, ??) at 0x100387f4
sh_exec(??, ??, ??) at 0x1003a120
IPRA.(??) at 0x10009328
IPRA.(??) at 0x1000a98c
copyto(??, ??, ??) at 0x1000af0c
mac_expand(??) at 0x1000b960
mac_trim(??, ??) at 0x1000b5dc
env_setlist(??, ??) at 0x10022034
IPRA.(??, ??, ??, ??, ??) at 0x10038c90
sh_exec(??, ??, ??) at 0x1003a120
IPRA.() at 0x10001b48
main(??, ??) at 0x10000e3c
Is this a known issue in PostgreSQL 15.12?
Are there recommended workarounds or configuration changes to avoid this behaviour?
Is there any way for pg_ctl to internally lock, to prevent such hangs?
Do we need to serialize pg_ctl stop and status, even if we are running different database?
Warm regards,
Sriram.
