Long semaphore wait in dict0dict.cc line 943 and semaphore wait >600 sec kill

DROP DATABASE test;

CREATE DATABASE test;

USE test;

CREATE TABLE t1 (a INT) ENGINE=InnoDB;

INSERT INTO t1 VALUES (NULL);

XA BEGIN 'x';

UPDATE t1 SET a = 1;

DELETE FROM t1;

ALTER TABLE t1 ADD COLUMN extra INT;

INSERT INTO t1 (a) VALUES (2);

ROLLBACK;

DELETE FROM t1;

INSERT INTO t1 (a) VALUES (2);

XA END 'x';

XA ROLLBACK 'x';

DROP TABLE t1;

2020-11-17 10:53:27 0 [Note] /test/MD211020-mariadb-10.6.0-linux-x86_64-dbg/bin/mysqld: ready for connections.

Version: '10.6.0-MariaDB-debug' socket: '/test/MD211020-mariadb-10.6.0-linux-x86_64-dbg/socket.sock' port: 12191 MariaDB Server

2020-11-17 10:53:35 499 [Note] InnoDB: Deferring DROP TABLE `test`.`t1`; renaming to test/#sql-ib33

2020-11-17 10:57:37 0 [Warning] InnoDB: A long semaphore wait:

--Thread 22831188305664 has waited at dict0dict.cc line 943 for 241.00 seconds the semaphore:

Mutex at 0x55e77c0b2a00, Mutex DICT_SYS created /test/10.6_dbg/storage/innobase/dict/dict0dict.cc:1032, lock var 2

Last time reserved in file /test/10.6_dbg/storage/innobase/row/row0mysql.cc line 3921

2020-11-17 10:57:37 0 [Note] InnoDB: A semaphore wait:

--Thread 22831188305664 has waited at dict0dict.cc line 943 for 241.00 seconds the semaphore:

Mutex at 0x55e77c0b2a00, Mutex DICT_SYS created /test/10.6_dbg/storage/innobase/dict/dict0dict.cc:1032, lock var 2

Last time reserved in file /test/10.6_dbg/storage/innobase/row/row0mysql.cc line 3921

InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:

InnoDB: Pending reads 0, writes 0

InnoDB: ###### Diagnostic info printed to the standard error stream

... many more (all on the same dict0dict.cc:943, dict0dict.cc:1032, and row0mysql.cc line 3921)...

2020-11-17 11:03:47 0 [ERROR] [FATAL] InnoDB: Semaphore wait has lasted > 600 seconds. We intentionally crash the server because it appears to be hung.

201117 11:03:47 [ERROR] mysqld got signal 6 ;

Core was generated by `/test/MD211020-mariadb-10.6.0-linux-x86_64-dbg/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGABRT, Aborted.

#0 __pthread_kill (threadid=<optimized out>, signo=signo@entry=6)

    at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

[Current thread is 1 (Thread 0x14c3ce1f0700 (LWP 827875))]

(gdb) bt

#0 __pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

#1 0x000055e77b698021 in my_write_core (sig=sig@entry=6) at /test/10.6_dbg/mysys/stacktrace.c:424

#2 0x000055e77addf321 in handle_fatal_signal (sig=6) at /test/10.6_dbg/sql/signal_handler.cc:330

#3 <signal handler called>

#4 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50

#5 0x000014c48b161859 in __GI_abort () at abort.c:79

#6 0x000055e77b4574b9 in ib::fatal::~fatal (this=<optimized out>, __in_chrg=<optimized out>) at /test/10.6_dbg/storage/innobase/ut/ut0ut.cc:580

#7 0x000055e77b3e5b04 in srv_error_monitor_task () at /test/10.6_dbg/storage/innobase/include/ut0ut.h:346

#8 0x000055e77b623746 in tpool::thread_pool_generic::timer_generic::run (this=0x55e77edb1af0) at /test/10.6_dbg/tpool/tpool_generic.cc:299

#9 tpool::thread_pool_generic::timer_generic::execute (arg=0x55e77edb1af0) at /test/10.6_dbg/tpool/tpool_generic.cc:317

#10 0x000055e77b62467f in tpool::task::execute (this=0x55e77edb1b30) at /test/10.6_dbg/tpool/task.cc:52

#11 0x000055e77b62325f in tpool::thread_pool_generic::worker_main (this=0x55e77e3f1b20, thread_var=0x55e77e42c4d0) at /test/10.6_dbg/tpool/tpool_generic.cc:518

#12 0x000055e77b623598 in std::__invoke_impl<void, void (tpool::thread_pool_generic::*)(tpool::worker_data*), tpool::thread_pool_generic*, tpool::worker_data*> (__t=<optimized out>, __f=<optimized out>) at /usr/include/c++/9/bits/invoke.h:89

#13 std::__invoke<void (tpool::thread_pool_generic::*)(tpool::worker_data*), tpool::thread_pool_generic*, tpool::worker_data*> (__fn=<optimized out>) at /usr/include/c++/9/bits/invoke.h:95

#14 std::thread::_Invoker<std::tuple<void (tpool::thread_pool_generic::*)(tpool::worker_data*), tpool::thread_pool_generic*, tpool::worker_data*> >::_M_invoke<0ul, 1ul, 2ul> (this=<optimized out>) at /usr/include/c++/9/thread:244

#15 std::thread::_Invoker<std::tuple<void (tpool::thread_pool_generic::*)(tpool::worker_data*), tpool::thread_pool_generic*, tpool::worker_data*> >::operator() (this=<optimized out>) at /usr/include/c++/9/thread:251

#16 std::thread::_State_impl<std::thread::_Invoker<std::tuple<void (tpool::thread_pool_generic::*)(tpool::worker_data*), tpool::thread_pool_generic*, tpool::worker_data*> > >::_M_run (this=<optimized out>) at /usr/include/c++/9/thread:195

#17 0x000014c48b553d84 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6

#18 0x000014c48b66f609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#19 0x000014c48b25e293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Core was generated by `/test/MD201020-mariadb-10.6.0-linux-x86_64-opt/bin/mysqld --no-defaults --core-'.

Program terminated with signal SIGABRT, Aborted.

#0 __pthread_kill (threadid=<optimized out>, signo=signo@entry=6)

    at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

[Current thread is 1 (Thread 0x148ea2df6700 (LWP 1128501))]

(gdb) bt

#0 __pthread_kill (threadid=<optimized out>, signo=signo@entry=6) at ../sysdeps/unix/sysv/linux/pthread_kill.c:56

#1 0x000055b083224a4f in my_write_core (sig=sig@entry=6) at /test/10.6_opt/mysys/stacktrace.c:424

#2 0x000055b082c48130 in handle_fatal_signal (sig=6) at /test/10.6_opt/sql/signal_handler.cc:330

#3 <signal handler called>

#4 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50

#5 0x0000148fb2181859 in __GI_abort () at abort.c:79

#6 0x000055b08290d1f7 in ib::fatal::~fatal (this=<optimized out>, __in_chrg=<optimized out>) at /test/10.6_opt/storage/innobase/ut/ut0ut.cc:580

#7 0x000055b082902fde in srv_error_monitor_task () at /test/10.6_opt/storage/innobase/include/ut0ut.h:346

#8 0x000055b0831b7159 in tpool::thread_pool_generic::timer_generic::run (this=0x55b08599f5a0) at /test/10.6_opt/tpool/tpool_generic.cc:299

#9 tpool::thread_pool_generic::timer_generic::execute (arg=0x55b08599f5a0) at /test/10.6_opt/tpool/tpool_generic.cc:317

#10 0x000055b0831b815a in tpool::task::execute (this=0x55b08599f5e0) at /test/10.6_opt/tpool/task.cc:52

#11 tpool::task::execute (this=0x55b08599f5e0) at /test/10.6_opt/tpool/task.cc:42

#12 0x000055b0831b6c47 in tpool::thread_pool_generic::worker_main (this=0x55b0853a52e0, thread_var=0x55b0853dec00) at /test/10.6_opt/tpool/tpool_generic.cc:518

#13 0x0000148fb2573d84 in ?? () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6

#14 0x0000148fb268f609 in start_thread (arg=<optimized out>) at pthread_create.c:477

#15 0x0000148fb227e293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95