BUG #18958: "pg_ctl start" allows subsequent CTRL-C key in cmd.exe to unexpectedly terminate cluster on Windows

The following bug has been logged on the website:

Bug reference: 18958
Logged by: Seva Zaslavsky
Email address: szaslavsky(at)mpcapitallp(dot)com
PostgreSQL version: 17.5
Operating system: Windows Server 2019
Description:

In the process of upgrading from PG 13.18 to PG 17.5, I see a dangerous
interaction/relation/link between the cmd.exe window that was used to run
"pg_ctl start" and the cluster that was started that allows subsequent
CTRL-C keypress in cmd.exe to unexpectedly terminate the cluster.
Very easy to replicate:
(1) Start by installing the community windows build of Postgresl 17.5 from
EDB https://www.enterprisedb.com/downloads/postgres-postgresql-downloads
(2) Change the logging config in postgresql.conf as follows:
log_destination = 'stderr'
logging_collector = on
log_directory = 'pg_log'
log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'
log_file_mode = 0640
log_rotation_age = 1d
log_min_messages = info
log_min_duration_statement = 30000
log_checkpoints = on
log_connections = on
log_disconnections = on
log_line_prefix = '%m [%p] [%a] '
(3) start a windows command line "cmd.exe" with administrator access
(4) Use "pg_ctl start" to start the cluster. The way I did it is shown in
the "cmd.exe Input/Output" section below. Now the cluster should be
started.
(5) Type the "exit" command and press "Enter" to close the cmd.exe window.
After entering the "exit" command, the cmd.exe window should normally close
and disappear but it just sits there.
(6) Click on the "X" in the upper-right corner which should close the
window. When I click on the "X" in the upper right of cmd.exe and the
window still does not close but it generates the output in the log starting
at 2025-06-13 08:45:21.441 below.
(7) Press CTRL-C with the cmd.exe window active. Then I press "CTRL-C" with
the cmd.exe window in focus, the cmd.exe window closes AND IT SHUTS DOWN THE
CLUSTER with the log output starting at 2025-06-13 08:48:51.597 below. I am
surprised that pressing CTRL-C in a command window would affect a running
cluster in any way.
=========== cmd.exe Input/Output ==============
Microsoft Windows [Version 10.0.17763.7136]
(c) 2018 Microsoft Corporation. All rights reserved.
J:\Users\Public\PostgreSQL\data>"c:\Program
Files\PostgreSQL\17.5\bin\pg_ctl" start -D
"J:\Users\Public\PostgreSQL\data\5438" -o "-p 5438"
waiting for server to start....2025-06-13 08:44:06.019 EDT [10020] [] LOG:
redirecting log output to logging collector process
2025-06-13 08:44:06.019 EDT [10020] [] HINT: Future log output will appear
in directory "pg_log".
done
server started
J:\Users\Public\PostgreSQL\data>exit
=========== end cmd.exe Input/Output ==============
=========== stderr-based log file ===============
2025-06-13 08:44:06.019 EDT [10020] [] LOG: starting PostgreSQL 17.5 on
x86_64-windows, compiled by msvc-19.43.34808, 64-bit
2025-06-13 08:44:06.021 EDT [10020] [] LOG: listening on IPv6 address "::",
port 5438
2025-06-13 08:44:06.021 EDT [10020] [] LOG: listening on IPv4 address
"0.0.0.0", port 5438
2025-06-13 08:44:06.084 EDT [6192] [] LOG: database system was shut down at
2025-06-11 15:03:46 EDT
2025-06-13 08:44:06.134 EDT [10020] [] LOG: could not reserve shared memory
region (addr=000001C45CBB0000) for child 000000000000219C: error code 487
2025-06-13 08:44:06.142 EDT [10020] [] LOG: database system is ready to
accept connections
<after clicking on the "X" in the upper-right corner of cmd.exe>
2025-06-13 08:45:21.441 EDT [10020] [] LOG: background worker "logical
replication launcher" (PID 24932) was terminated by exception 0xC000013A
2025-06-13 08:45:21.441 EDT [10020] [] HINT: See C include file
"ntstatus.h" for a description of the hexadecimal value.
2025-06-13 08:45:21.441 EDT [10020] [] LOG: terminating any other active
server processes
2025-06-13 08:45:21.461 EDT [10020] [] LOG: all server processes
terminated; reinitializing
2025-06-13 08:45:22.408 EDT [13752] [] LOG: database system was
interrupted; last known up at 2025-06-13 08:44:06 EDT
2025-06-13 08:45:22.601 EDT [13752] [] LOG: database system was not
properly shut down; automatic recovery in progress
2025-06-13 08:45:22.603 EDT [13752] [] LOG: redo starts at 0/4B0000A0
2025-06-13 08:45:22.603 EDT [13752] [] LOG: invalid record length at
0/4B0000D8: expected at least 24, got 0
2025-06-13 08:45:22.603 EDT [13752] [] LOG: redo done at 0/4B0000A0 system
usage: CPU: user: 0.00 s, system: 0.00 s, elapsed: 0.00 s
2025-06-13 08:45:22.606 EDT [27952] [] LOG: checkpoint starting:
end-of-recovery immediate wait
2025-06-13 08:45:22.889 EDT [27952] [] LOG: checkpoint complete: wrote 3
buffers (0.0%); 0 WAL file(s) added, 0 removed, 0 recycled; write=0.280 s,
sync=0.002 s, total=0.285 s; sync files=2, longest=0.001 s, average=0.001 s;
distance=0 kB, estimate=0 kB; lsn=0/4B0000D8, redo lsn=0/4B0000D8
2025-06-13 08:45:22.912 EDT [10020] [] LOG: database system is ready to
accept connections
<pressing CTRL-C with the cmd.exe window being active>
2025-06-13 08:48:51.597 EDT [18868] [] ERROR: canceling statement due to
user request
2025-06-13 08:48:51.597 EDT [10144] [] ERROR: canceling statement due to
user request
2025-06-13 08:48:51.598 EDT [10020] [] LOG: received fast shutdown request
2025-06-13 08:48:51.599 EDT [10020] [] LOG: aborting any active
transactions
2025-06-13 08:48:51.605 EDT [10020] [] LOG: background worker "logical
replication launcher" (PID 18868) exited with exit code 1
2025-06-13 08:48:51.626 EDT [27952] [] LOG: shutting down
2025-06-13 08:48:51.646 EDT [27952] [] LOG: checkpoint starting: shutdown
immediate
2025-06-13 08:48:51.749 EDT [27952] [] LOG: checkpoint complete: wrote 0
buffers (0.0%); 0 WAL file(s) added, 0 removed, 1 recycled; write=0.100 s,
sync=0.001 s, total=0.105 s; sync files=0, longest=0.000 s, average=0.000 s;
distance=16383 kB, estimate=16383 kB; lsn=0/4C000028, redo lsn=0/4C000028
2025-06-13 08:48:52.105 EDT [10020] [] LOG: database system is shut down