dberr_t fts_sync(fts_sync_t*, bool, bool): Assertion `sync->unlock_cache' failed.

Assert hit when RQG testing on

- bb-10.5-MDEV-16678 f0c597f712589414d8836ca8cc5cba9107e15f11 2019-10-31

- bb-10.5-wlad-MDEV-16264 8ea7b2e6695cd07a6354907d936f94c90c6590a4 2019-11-04

So its likely that the actual 10.5 contains the same problem too.

[Note] bb-10.5-MDEV-16678/bld_debug/sql/mysqld: ready for connections.

Version: '10.5.0-MariaDB-debug-log'  socket: ...

mysqld: bb-10.5-MDEV-16678/storage/innobase/fts/fts0fts.cc:4287: dberr_t fts_sync(fts_sync_t*, bool, bool): Assertion `sync->unlock_cache' failed.

[ERROR] mysqld got signal 6 ;

...

Query (0x7f6e300114d0): ALTER TABLE `table200_innodb_int_autoinc` ADD FULLTEXT INDEX idx_2 (`c9`) /* E_R Thread13 QNO 131 CON_ID 24 */

Connection ID (thread ID): 24

Status: NOT_KILLED

Thread 1 (Thread 0x7f6ed0137700 (LWP 312101)):

#0  __pthread_kill (threadid=<optimized out>, signo=6) at ../sysdeps/unix/sysv/linux/pthread_kill.c:62

#1  0x000055fd2fbda0e8 in my_write_core (sig=6) at bb-10.5-MDEV-16678/mysys/stacktrace.c:518

#2  0x000055fd2f2df54d in handle_fatal_signal (sig=6) at bb-10.5-MDEV-16678/sql/signal_handler.cc:343

#3  <signal handler called>

#4  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:58

#5  0x00007f6ee78a137a in __GI_abort () at abort.c:89 

#6  0x00007f6ee7897b47 in __assert_fail_base (fmt=<optimized out>, assertion=assertion@entry=0x55fd3012cbb0 "sync->unlock_cache", file=file@entry=0x55fd3012bb20 "bb-10.5-MDEV-16678/storage/innobase/fts/fts0fts.cc", line=line@entry=4287, function=function@entry=0x55fd3012f820 <fts_sync(fts_sync_t*, bool, bool)::__PRETTY_FUNCTION__> "dberr_t fts_sync(fts_sync_t*, bool, bool)") at assert.c:92

#7  0x00007f6ee7897bf2 in __GI___assert_fail (assertion=0x55fd3012cbb0 "sync->unlock_cache", file=0x55fd3012bb20 "bb-10.5-MDEV-16678/storage/innobase/fts/fts0fts.cc", line=4287, function=0x55fd3012f820 <fts_sync(fts_sync_t*, bool, bool)::__PRETTY_FUNCTION__> "dberr_t fts_sync(fts_sync_t*, bool, bool)") at assert.c:101

#8  0x000055fd2fadc1ec in fts_sync (sync=0x7f6e1c06f850, unlock_cache=false, wait=true) at bb-10.5-MDEV-16678/storage/innobase/fts/fts0fts.cc:4287

#9  0x000055fd2fadc53d in fts_sync_table (table=0x7f6e1c0300d8, wait=true) at bb-10.5-MDEV-16678/storage/innobase/fts/fts0fts.cc:4370

#10 0x000055fd2f87cc77 in row_merge_read_clustered_index (trx=0x7f6ee452bf50, table=0x7f6ed0133010, old_table=0x7f6e1c0300d8, new_table=0x7f6e1c0300d8, online=false, index=0x7f6e30085c38, fts_sort_idx=0x7f6e300c1628, psort_info=0x7f6e300d1b00, files=0x7f6e300737a0, key_numbers=0x7f6e30085c40, n_index=1, defaults=0x0, add_v=0x0, col_map=0x0, add_autoinc=18446744073709551615, sequence=..., block=0x7f6e844f9000 <error: Cannot access memory at address 0x7f6e844f9000>, skip_pk_sort=false, tmpfd=0x7f6ed0131f20, stage=0x7f6e3009c260, pct_cost=50, crypt_block=0x0, eval_table=0x7f6ed0133010, allow_not_null=false) at bb-10.5-MDEV-16678/storage/innobase/row/row0merge.cc:2863

#11 0x000055fd2f882d18 in row_merge_build_indexes (trx=0x7f6ee452bf50, old_table=0x7f6e1c0300d8, new_table=0x7f6e1c0300d8, online=false, indexes=0x7f6e30085c38, key_numbers=0x7f6e30085c40, n_indexes=1, table=0x7f6ed0133010, defaults=0x0, col_map=0x0, add_autoinc=18446744073709551615, sequence=..., skip_pk_sort=false, stage=0x7f6e3009c260, add_v=0x0, eval_table=0x7f6ed0133010, allow_not_null=false) at bb-10.5-MDEV-16678/storage/innobase/row/row0merge.cc:4726

#12 0x000055fd2f72d584 in ha_innobase::inplace_alter_table (this=0x7f6e30163ca0, altered_table=0x7f6ed0133010, ha_alter_info=0x7f6ed0132f80) at bb-10.5-MDEV-16678/storage/innobase/handler/handler0alter.cc:8328

#13 0x000055fd2f0a3e1b in handler::ha_inplace_alter_table (this=0x7f6e30163ca0, altered_table=0x7f6ed0133010, ha_alter_info=0x7f6ed0132f80) at bb-10.5-MDEV-16678/sql/handler.h:4339

#14 0x000055fd2f097e26 in mysql_inplace_alter_table (thd=0x7f6e30000aa8, table_list=0x7f6e300116e0, table=0x7f6e30170768, altered_table=0x7f6ed0133010, ha_alter_info=0x7f6ed0132f80, inplace_supported=HA_ALTER_INPLACE_NOCOPY_LOCK, target_mdl_request=0x7f6ed0133df0, alter_ctx=0x7f6ed0134920) at bb-10.5-MDEV-16678/sql/sql_table.cc:7724

#15 0x000055fd2f09eb7a in mysql_alter_table (thd=0x7f6e30000aa8, new_db=0x7f6e30005270, new_name=0x7f6e30005678, create_info=0x7f6ed0135510, table_list=0x7f6e300116e0, alter_info=0x7f6ed0135450, order_num=0, order=0x0, ignore=false) at bb-10.5-MDEV-16678/sql/sql_table.cc:10090

#16 0x000055fd2f14015f in Sql_cmd_alter_table::execute (this=0x7f6e30011e70, thd=0x7f6e30000aa8) at bb-10.5-MDEV-16678/sql/sql_alter.cc:522

#17 0x000055fd2efa8455 in mysql_execute_command (thd=0x7f6e30000aa8) at bb-10.5-MDEV-16678/sql/sql_parse.cc:5951

#18 0x000055fd2efae66a in mysql_parse (thd=0x7f6e30000aa8, rawbuf=0x7f6e300114d0 "ALTER TABLE `table200_innodb_int_autoinc` ADD FULLTEXT INDEX idx_2 (`c9`) /* E_R Thread13 QNO 131 CON_ID 24 */", length=110, parser_state=0x7f6ed01365d0, is_com_multi=false, is_next_command=false) at bb-10.5-MDEV-16678/sql/sql_parse.cc:7998

#19 0x000055fd2ef99817 in dispatch_command (command=COM_QUERY, thd=0x7f6e30000aa8, packet=0x7f6e30008099 "ALTER TABLE `table200_innodb_int_autoinc` ADD FULLTEXT INDEX idx_2 (`c9`) /* E_R Thread13 QNO 131 CON_ID 24 */ ", packet_length=111, is_com_multi=false, is_next_command=false) at bb-10.5-MDEV-16678/sql/sql_parse.cc:1845

#20 0x000055fd2ef97f71 in do_command (thd=0x7f6e30000aa8) at bb-10.5-MDEV-16678/sql/sql_parse.cc:1363

#21 0x000055fd2f13609a in do_handle_one_connection (connect=0x55fd32eff3f8, put_in_cache=true) at bb-10.5-MDEV-16678/sql/sql_connect.cc:1422

#22 0x000055fd2f135dce in handle_one_connection (arg=0x55fd32eff3f8) at bb-10.5-MDEV-16678/sql/sql_connect.cc:1319

#23 0x00007f6ee86e46da in start_thread (arg=0x7f6ed0137700) at pthread_create.c:456

#24 0x00007f6ee7972d7f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:105