main.innodb_mrr_cpk failed in buildbot with server crash

main.innodb_mrr_cpk 'innodb'             w3 [ fail ]

        Test ended at 2020-11-10 03:06:04

CURRENT_TEST: main.innodb_mrr_cpk

mysqltest: At line 221: query 'drop table t0,t1,t2' failed: 2013: Lost connection to MySQL server during query

The result from queries just before the failure was:

< snip >

create table  t0 (a int);

insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);

CREATE TABLE t1 (

id char(8) CHARACTER SET utf8 NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE t2 (

id char(8) CHARACTER SET utf8 DEFAULT NULL,

url text CHARACTER SET utf8

) ENGINE=InnoDB DEFAULT CHARSET=latin1;

insert into t1 select '03b2ca8c' from t0 A, t0 B limit 80;

insert into t2 select '03b2ca8c','' from t0 A, t0 B, t0 C;

set @tmp_mdev5037=@@join_cache_level;

set join_cache_level=3;

explain SELECT 1 FROM (SELECT url, id FROM t2 LIMIT 1 OFFSET 20) derived RIGHT JOIN t1 ON t1.id = derived.id;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra

1	PRIMARY	t1	ALL	NULL	NULL	NULL	NULL	#	

1	PRIMARY	<derived2>	ref	key0	key0	25	test.t1.id	#	

2	DERIVED	t2	ALL	NULL	NULL	NULL	NULL	#	

set join_cache_level= @tmp_mdev5037;

drop table t0,t1,t2;

More results from queries before failure can be found in /dev/shm/var/3/log/innodb_mrr_cpk.log

Server [mysqld.1 - pid: 12524, winpid: 12524, exit: 256] failed during test run

Server log from this test:

----------SERVER LOG START-----------

201110  3:05:57 [ERROR] mysqld got signal 6 ;

This could be because you hit a bug. It is also possible that this binary

or one of the libraries it was linked against is corrupt, improperly built,

or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help

diagnose the problem, but since we have already crashed, 

something is definitely wrong and this may fail.

Server version: 10.2.36-MariaDB-10.2.36+maria~xenial-log

key_buffer_size=1048576

read_buffer_size=131072

max_used_connections=1

max_threads=153

thread_count=11

It is possible that mysqld could use up to 

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 63019 K  bytes of memory

Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7f89500009a8

Attempting backtrace. You can use the following information to find out

where mysqld died. If you see no messages after this, something went

terribly wrong...

stack_bottom = 0x7f895affcb28 thread_stack 0x49000

/usr/sbin/mysqld(my_print_stacktrace+0x2e)[0x55fe5b3ba1ae]

/usr/sbin/mysqld(handle_fatal_signal+0x305)[0x55fe5ae6c305]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x11390)[0x7f897a670390]

/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x38)[0x7f8979c3f438]

/lib/x86_64-linux-gnu/libc.so.6(abort+0x16a)[0x7f8979c4103a]

/lib/x86_64-linux-gnu/libc.so.6(+0x777fa)[0x7f8979c817fa]

/lib/x86_64-linux-gnu/libc.so.6(+0x8038a)[0x7f8979c8a38a]

/lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7f8979c8e58c]

/usr/sbin/mysqld(+0xab7284)[0x55fe5b299284]

/usr/sbin/mysqld(+0xa5197d)[0x55fe5b23397d]

/usr/sbin/mysqld(+0xa83c26)[0x55fe5b265c26]

/usr/sbin/mysqld(+0xa85d68)[0x55fe5b267d68]

/usr/sbin/mysqld(+0xa86960)[0x55fe5b268960]

/usr/sbin/mysqld(+0xa63240)[0x55fe5b245240]

/usr/sbin/mysqld(+0xa8ac5e)[0x55fe5b26cc5e]

/usr/sbin/mysqld(+0xa61ce3)[0x55fe5b243ce3]

/usr/sbin/mysqld(+0x9ea8ab)[0x55fe5b1cc8ab]

/usr/sbin/mysqld(+0x9f2798)[0x55fe5b1d4798]

/usr/sbin/mysqld(+0x9d2fa2)[0x55fe5b1b4fa2]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ba)[0x7f897a6666ba]

/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f8979d114dd]

Trying to get some variables.

Some pointers may be invalid and cause the dump to abort.

Query (0x0): (null)

Connection ID (thread ID): 1

Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on

The manual page at https://mariadb.com/kb/en/how-to-produce-a-full-stack-trace-for-mysqld/ contains

information that should help you find out what is causing the crash.

We think the query pointer is invalid, but we will try to print it anyway. 

Query: 

Writing a core file...

Working directory at /dev/shm/var/3/mysqld.1/data

Resource Limits:

Limit                     Soft Limit           Hard Limit           Units     

Max cpu time              unlimited            unlimited            seconds   

Max file size             unlimited            unlimited            bytes     

Max data size             unlimited            unlimited            bytes     

Max stack size            8388608              unlimited            bytes     

Max core file size        unlimited            unlimited            bytes     

Max resident set          unlimited            unlimited            bytes     

Max processes             23720                23720                processes 

Max open files            1024                 1024                 files     

Max locked memory         65536                65536                bytes     

Max address space         unlimited            unlimited            bytes     

Max file locks            unlimited            unlimited            locks     

Max pending signals       23720                23720                signals   

Max msgqueue size         819200               819200               bytes     

Max nice priority         0                    0                    

Max realtime priority     0                    0                    

Max realtime timeout      unlimited            unlimited            us        

Core pattern: |/usr/share/apport/apport %p %s %c %P

----------SERVER LOG END-------------

 - found 'core' (0/0)