Re: [Patch] ALTER SYSTEM READ ONLY - Mailing list pgsql-hackers

Hi all,
While testing this feature with v20-patch, the server is crashing with below steps.

Steps to reproduce:
1. Configure master-slave replication setup.
2. Connect to Slave.
3. Execute below statements, it will crash the server:
SELECT pg_prohibit_wal(true);
SELECT pg_prohibit_wal(false);

-- Slave:
postgres=# select pg_is_in_recovery();
 pg_is_in_recovery
-------------------
 t
(1 row)

postgres=# SELECT pg_prohibit_wal(true);
 pg_prohibit_wal
-----------------
 
(1 row)

postgres=# SELECT pg_prohibit_wal(false);
WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
HINT:  In a moment you should be able to reconnect to the database and repeat your command.
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!?>

-- Below are the stack trace:
[prabhat@localhost bin]$ gdb -q -c /tmp/data_slave/core.35273 postgres
Reading symbols from /home/prabhat/PG/PGsrcNew/postgresql/inst/bin/postgres...done.
[New LWP 35273]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Core was generated by `postgres: checkpointer                                                       '.
Program terminated with signal 6, Aborted.
#0  0x00007fa876233387 in raise () from /lib64/libc.so.6
Missing separate debuginfos, use: debuginfo-install glibc-2.17-317.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64 krb5-libs-1.15.1-50.el7.x86_64 libcom_err-1.42.9-19.el7.x86_64 libgcc-4.8.5-44.el7.x86_64 libselinux-2.5-15.el7.x86_64 openssl-libs-1.0.2k-21.el7_9.x86_64 pcre-8.32-17.el7.x86_64 zlib-1.2.7-18.el7.x86_64
(gdb) bt
#0  0x00007fa876233387 in raise () from /lib64/libc.so.6
#1  0x00007fa876234a78 in abort () from /lib64/libc.so.6
#2  0x0000000000aea31c in ExceptionalCondition (conditionName=0xb8c998 "ThisTimeLineID != 0 || IsBootstrapProcessingMode()",
    errorType=0xb8956d "FailedAssertion", fileName=0xb897c0 "xlog.c", lineNumber=8611) at assert.c:69
#3  0x0000000000588eb5 in InitXLOGAccess () at xlog.c:8611
#4  0x0000000000588ae6 in LocalSetXLogInsertAllowed () at xlog.c:8483
#5  0x00000000005881bb in XLogAcceptWrites (needChkpt=true, xlogreader=0x0, EndOfLog=0, EndOfLogTLI=0) at xlog.c:8008
#6  0x00000000005751ed in ProcessWALProhibitStateChangeRequest () at walprohibit.c:361
#7  0x000000000088c69f in CheckpointerMain () at checkpointer.c:355
#8  0x000000000059d7db in AuxiliaryProcessMain (argc=2, argv=0x7ffd1290d060) at bootstrap.c:455
#9  0x000000000089fc5f in StartChildProcess (type=CheckpointerProcess) at postmaster.c:5416
#10 0x000000000089f782 in sigusr1_handler (postgres_signal_arg=10) at postmaster.c:5128
#11 <signal handler called>
#12 0x00007fa8762f2983 in __select_nocancel () from /lib64/libc.so.6
#13 0x000000000089b511 in ServerLoop () at postmaster.c:1700
#14 0x000000000089af00 in PostmasterMain (argc=5, argv=0x15b8460) at postmaster.c:1408
#15 0x000000000079c23a in main (argc=5, argv=0x15b8460) at main.c:209
(gdb)

kindly let me know if you need more inputs on this.