By the way, thread 9 is the query that always hangs the server for the last few times

Thread 9 (Thread 0x7f31cb99e700 (LWP 27968)):
#0  0x00007f31cce007be in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/x86_64-linux-gnu/libpthread.so.0
#1  0x00007f31c9d207ec in toku_cond_timedwait (cond=<optimized out>, mutex=<optimized out>, wakeup_at=<optimized out>) at /home/jynus/mariadb-10.0.22/storage/tokudb/ft-index/portabi
lity/toku_pthread.h:325
#2  wait (killed_callback=0x7f31c9c6fdd0 <tokudb_killed_callback()>, killed_time_ms=<optimized out>, wait_time_ms=<optimized out>, this=0x7f31cb99b460) at /home/jynus/mariadb-10.0.2
2/storage/tokudb/ft-index/locktree/lock_request.cc:273
#3  toku_db_wait_range_lock (db=db@entry=0x7f2c59fdb0c0, txn=txn@entry=0x7f2f2d1b8e00, request=request@entry=0x7f31cb99b460) at /home/jynus/mariadb-10.0.22/storage/tokudb/ft-index/s
rc/ydb_row_lock.cc:279
#4  0x00007f31c9d3cbd6 in toku_db_get_range_lock (db=db@entry=0x7f2c59fdb0c0, txn=txn@entry=0x7f2f2d1b8e00, left_key=left_key@entry=0x7f31cb99b890, right_key=right_key@entry=0x7f31c
b99b890, lock_type=lock_type@entry=toku::lock_request::WRITE)
    at /home/jynus/mariadb-10.0.22/storage/tokudb/ft-index/src/ydb_row_lock.cc:239
#5  0x00007f31c9d3d113 in toku_db_get_point_write_lock (db=db@entry=0x7f2c59fdb0c0, txn=txn@entry=0x7f2f2d1b8e00, key=key@entry=0x7f31cb99b890) at /home/jynus/mariadb-10.0.22/storag
e/tokudb/ft-index/src/ydb_row_lock.cc:293
#6  0x00007f31c9d3d752 in env_put_multiple_internal (flags_array=0x7f2c59943420, vals=0x7f2c59943010, keys=0x7f2c599427f0, db_array=0x7f2c59987158, num_dbs=2, src_val=0x7f31cb99b870
, src_key=0x7f31cb99b890, txn=0x7f2f2d1b8e00, src_db=0x7f2c59fdb0c0, env=0x7f2fa83c1980)
    at /home/jynus/mariadb-10.0.22/storage/tokudb/ft-index/src/ydb_write.cc:790
#7  env_put_multiple (env=0x7f2fa83c1980, src_db=0x7f2c59fdb0c0, txn=0x7f2f2d1b8e00, src_key=0x7f31cb99b890, src_val=0x7f31cb99b870, num_dbs=2, db_array=0x7f2c59987158, keys=0x7f2c5
99427f0, vals=0x7f2c59943010, flags_array=0x7f2c59943420)
    at /home/jynus/mariadb-10.0.22/storage/tokudb/ft-index/src/ydb_write.cc:1174
#8  0x00007f31c9c86bd8 in ha_tokudb::insert_rows_to_dictionaries_mult (this=this@entry=0x7f2c59942020, pk_key=pk_key@entry=0x7f31cb99b890, pk_val=pk_val@entry=0x7f31cb99b870, txn=tx
n@entry=0x7f2f2d1b8e00, thd=thd@entry=0x7f2f4c014008)
    at /home/jynus/mariadb-10.0.22/storage/tokudb/ha_tokudb.cc:3852
#9  0x00007f31c9c95071 in ha_tokudb::write_row (this=0x7f2c59942020, record=0x7f2c59fea820 "@\321\a") at /home/jynus/mariadb-10.0.22/storage/tokudb/ha_tokudb.cc:4006
#10 0x0000000000747f7b in handler::ha_write_row (this=0x7f2c59942020, buf=0x7f2c59fea820 "@\321\a") at /home/jynus/mariadb-10.0.22/sql/handler.cc:6004
#11 0x00000000005b59bf in write_record (thd=thd@entry=0x7f2f4c014008, table=table@entry=0x7f2c5988b208, info=info@entry=0x7f31cb99bb80) at /home/jynus/mariadb-10.0.22/sql/sql_insert
.cc:1847
#12 0x00000000005b8fcb in mysql_insert (thd=thd@entry=0x7f2f4c014008, table_list=0x7f2f4c0300e8, fields=..., values_list=..., update_fields=..., update_values=..., duplic=DUP_ERROR,
 ignore=true) at /home/jynus/mariadb-10.0.22/sql/sql_insert.cc:964
#13 0x00000000005d511c in mysql_execute_command (thd=thd@entry=0x7f2f4c014008) at /home/jynus/mariadb-10.0.22/sql/sql_parse.cc:3448
#14 0x00000000005d9a5a in mysql_parse (thd=0x7f2f4c014008, rawbuf=<optimized out>, length=106, parser_state=parser_state@entry=0x7f31cb99d3e0) at /home/jynus/mariadb-10.0.22/sql/sql
_parse.cc:6546
#15 0x000000000081bc5d in Query_log_event::do_apply_event (this=0x7f2c75356ec8, rgi=0x7f2f32047b00, query_arg=0x7f2f2d25c213 "INSERT /* User::addGroup 127.0.0.1 */ IGNORE INTO `user
_groups` (ug_user,ug_group) VALUES ('512320','bot')", q_len_arg=106)
    at /home/jynus/mariadb-10.0.22/sql/log_event.cc:4347
#16 0x000000000055aebd in apply_event (rgi=0x7f2f32047b00, this=0x7f2c75356ec8) at /home/jynus/mariadb-10.0.22/sql/log_event.h:1360
#17 apply_event_and_update_pos (ev=ev@entry=0x7f2c75356ec8, thd=thd@entry=0x7f2f4c014008, rgi=rgi@entry=0x7f2f32047b00, rpt=rpt@entry=0x7f2f4f0f2468) at /home/jynus/mariadb-10.0.22/
sql/slave.cc:3290
#18 0x00000000006e5da7 in rpt_handle_event (qev=qev@entry=0x7f2d8f16bc08, rpt=rpt@entry=0x7f2f4f0f2468) at /home/jynus/mariadb-10.0.22/sql/rpl_parallel.cc:49
#19 0x00000000006e6a74 in retry_event_group (rgi=rgi@entry=0x7f2f32047b00, rpt=rpt@entry=0x7f2f4f0f2468, orig_qev=orig_qev@entry=0x7f2f47ce4708) at /home/jynus/mariadb-10.0.22/sql/r
pl_parallel.cc:592
#20 0x00000000006e8785 in handle_rpl_parallel_thread (arg=<optimized out>) at /home/jynus/mariadb-10.0.22/sql/rpl_parallel.cc:977
#21 0x00007f31ccdfc184 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#22 0x00007f31cbce037d in clone () from /lib/x86_64-linux-gnu/libc.so.6