$ mysql --defaults-file=my.cnf -e 'create sequence test.a'

$ mysqlsqldump --defaults-file=my.cnf test > /dev/null

mysqldump: Couldn't execute 'UNLOCK TABLES': Lost connection to MySQL server during query (2013)

2017-05-24  7:42:23 140019178026496 [Note] /home/a/test1/_depot/10.3-14465/bin/mysqld: ready for connections.

Version: '10.3.1-MariaDB'  socket: '/home/a/test1/mariadb-environs/m4-10.3~latest/dt/my.sock'  port: 3306  MariaDB Server

2017-05-24  7:42:53 140019102463744 [ERROR] Transaction not registered for MariaDB 2PC, but transaction is active

2017-05-24 07:42:53 0x7f58bcdd3700  InnoDB: Assertion failure in file /home/buildbot/buildbot/build/storage/innobase/trx/trx0trx.cc line 1737

InnoDB: Failing assertion: UT_LIST_GET_LEN(trx->lock.trx_locks) == 0

InnoDB: We intentionally generate a memory trap.

InnoDB: Submit a detailed bug report to http://bugs.mysql.com.

InnoDB: If you get repeated assertion failures or crashes, even

InnoDB: immediately after the mysqld startup, there may be

InnoDB: corruption in the InnoDB tablespace. Please refer to

InnoDB: http://dev.mysql.com/doc/refman/5.7/en/forcing-innodb-recovery.html

InnoDB: about forcing recovery.

170524  7:42:53 [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: 10.3.1-MariaDB

key_buffer_size=134217728

read_buffer_size=131072

max_used_connections=1

max_threads=153

thread_count=7

It is possible that mysqld could use up to

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 467233 K  bytes of memory

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

Thread pointer: 0x7f58480009a8

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 = 0x7f58bcdd2ec0 thread_stack 0x49000

/home/a/test1/mariadb-environs/m4-10.3~latest/../_depot/m-tar/10.3-14465/bin/mysqld(my_print_stacktrace+0x2b)[0x5581a4bcd4db]

/home/a/test1/mariadb-environs/m4-10.3~latest/../_depot/m-tar/10.3-14465/bin/mysqld(handle_fatal_signal+0x4d5)[0x5581a4661af5]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x11630)[0x7f58c098e630]

/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x9f)[0x7f58bff5a7ef]

/lib/x86_64-linux-gnu/libc.so.6(abort+0x16a)[0x7f58bff5c3ea]

/home/a/test1/mariadb-environs/m4-10.3~latest/../_depot/m-tar/10.3-14465/bin/mysqld(+0x4a2048)[0x5581a4409048]

/home/a/test1/mariadb-environs/m4-10.3~latest/../_depot/m-tar/10.3-14465/bin/mysqld(+0x9cfcf9)[0x5581a4936cf9]

/home/a/test1/mariadb-environs/m4-10.3~latest/../_depot/m-tar/10.3-14465/bin/mysqld(+0x9cff9a)[0x5581a4936f9a]

mysys/stacktrace.c:268(my_print_stacktrace)[0x5581a49371a7]

ut/ut0rbt.cc:459(rbt_eject_node(ib_rbt_node_t*, ib_rbt_node_t*) [clone .part.4])[0x5581a47c6bf1]

handler/ha_innodb.cc:4571(innobase_commit_low(trx_t*))[0x5581a47c6e8a]

handler/ha_innodb.cc:4707(innobase_commit_ordered_2(trx_t*, THD*))[0x5581a47d95f3]

handler/ha_innodb.cc:16526(ha_innobase::external_lock(THD*, int))[0x5581a47db4d5]

sql/ha_sequence.cc:320(ha_sequence::external_lock(THD*, int))[0x5581a4ba9205]

sql/handler.cc:5891(handler::ha_external_lock(THD*, int))[0x5581a466b00c]

sql/lock.cc:716(unlock_external(THD*, TABLE**, unsigned int))[0x5581a47252fb]

sql/lock.cc:428(mysql_unlock_tables(THD*, st_mysql_lock*, bool))[0x5581a47254ab]

sql/sql_base.cc:841(close_thread_tables(THD*))[0x5581a4474f87]

sql/sql_base.cc:2171(Locked_tables_list::unlock_locked_tables(THD*))[0x5581a44758da]

sql/sql_parse.cc:4979(mysql_execute_command(THD*))[0x5581a44c2d8c]

sql/sql_parse.cc:7912(mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool))[0x5581a44c575a]

sql/sql_parse.cc:1817(dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool))[0x5581a44c79ca]

sql/sql_parse.cc:1382(do_command(THD*))[0x5581a44c7f91]

sql/sql_connect.cc:1354(do_handle_one_connection(CONNECT*))[0x5581a45840ef]

sql/sql_connect.cc:1262(handle_one_connection)[0x5581a4584214]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x76ca)[0x7f58c09846ca]

/lib/x86_64-linux-gnu/libc.so.6(clone+0x5f)[0x7f58c002d0af]

Trying to get some variables.

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

Query (0x7f58480111b0): UNLOCK TABLES

Connection ID (thread ID): 10

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 http://dev.mysql.com/doc/mysql/en/crashing.html contains

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