galera_3nodes.galera_safe_to_bootstrap MTR sporadaically fails: Failed to start mysqld or mysql_shutdown failed

galera_3nodes.galera_safe_to_bootstrap 'innodb' w1 [ fail ]worker[1] > Restart  - using different config file

        Test ended at 2020-10-22 11:23:56

CURRENT_TEST: galera_3nodes.galera_ipv6_mariabackup_section

CURRENT_TEST: galera_3nodes.galera_ipv6_mariabackup_section

CURRENT_TEST: galera_3nodes.galera_ipv6_rsync

CURRENT_TEST: galera_3nodes.galera_safe_to_bootstrap

worker[1] > Restart  - using different config file

Failed to start mysqld.3

worker[1] > Restart  - using different config file

 - skipping '/dev/shm/var/1/log/galera_3nodes.galera_safe_to_bootstrap-innodb/'

Retrying test galera_3nodes.galera_safe_to_bootstrap, attempt(2/3)...

***Warnings generated in error logs during shutdown after running tests: galera_3nodes.galera_safe_to_bootstrap

WSREP_SST: [ERROR] rsync daemon port '16011' has been taken (20201022 11:23:48.467)

2020-10-22 11:23:48 140023005419264 [ERROR] WSREP: Failed to read 'ready <addr>' from: wsrep_sst_rsync --role 'joiner' --address '127.0.0.1:16011' --datadir '/dev/shm/var/1/mysqld.3/data/' --defaults-file '/dev/shm/var/1/my.cnf' --defaults-group-suffix '.3' --parent '30518' --binlog-index 'mysqld-bin.index' --mysqld-args --defaults-group-suffix=.3 --defaults-file=/dev/shm/var/1/my.cnf --log-output=file --innodb --innodb-cmpmem --innodb-cmp-per-index --innodb-trx --innodb-locks --innodb-metrics --innodb-buffer-pool-stats --innodb-buffer-page --innodb-buffer-page-lru --innodb-sys-columns --innodb-sys-fields --innodb-sys-foreign --innodb-sys-foreign-cols --innodb-sys-indexes --innodb-sys-tables --innodb-sys-virtual --core-file --loose-debug-sync-timeout=300

2020-10-22 11:23:48 140023005419264 [ERROR] WSREP: Process completed with error: wsrep_sst_rsync --role 'joiner' --address '127.0.0.1:16011' --datadir '/dev/shm/var/1/mysqld.3/data/' --defaults-file '/dev/shm/var/1/my.cnf' --defaults-group-suffix '.3' --parent '30518' --binlog-index 'mysqld-bin.index' --mysqld-args --defaults-group-suffix=.3 --defaults-file=/dev/shm/var/1/my.cnf --log-output=file --innodb --innodb-cmpmem --innodb-cmp-per-index --innodb-trx --innodb-locks --innodb-metrics --innodb-buffer-pool-stats --innodb-buffer-page --innodb-buffer-page-lru --innodb-sys-columns --innodb-sys-fields --innodb-sys-foreign --innodb-sys-foreign-cols --innodb-sys-indexes --innodb-sys-tables --innodb-sys-virtual --core-file --loose-debug-sync-timeout=300: 16 (Device or resource busy)

2020-10-22 11:23:48 140023253743360 [ERROR] WSREP: Failed to prepare for 'rsync' SST. Unrecoverable.

2020-10-22 11:23:48 140023253743360 [ERROR] Aborting

Warning: Memory not freed: 1427648

galera_3nodes.galera_safe_to_bootstrap 'innodb' w1 [ fail ]

        Test ended at 2020-10-30 08:09:16

CURRENT_TEST: galera_3nodes.galera_safe_to_bootstrap

mysqltest: In included file "./include/shutdown_mysqld.inc": 

included from /usr/share/mysql/mysql-test/suite/galera_3nodes/t/galera_safe_to_bootstrap.test at line 50:

At line 40: mysql_shutdown failed

The result from queries just before the failure was:

connection node_2;

connection node_1;

connection node_1;

connection node_2;

connection node_3;

connection node_1;

CREATE TABLE t1 (f1 INTEGER NOT NULL PRIMARY KEY) ENGINE=InnoDB;

INSERT INTO t1 VALUES (1);

include/assert_grep.inc [grastate.dat does not have 'safe_to_bootstrap: 0']

include/assert_grep.inc [grastate.dat does not have 'safe_to_bootstrap: 0']

include/assert_grep.inc [grastate.dat does not have 'safe_to_bootstrap: 0']

connection node_2;