A duplicate of  https://bugs.launchpad.net/galera/+bug/928919 reported earlier. 

But, it looks like a local TOI can block all actions, which also includes DML.

Stacktrace shows it:

Thread 4 (Thread 0x7fdfc02c1700 (LWP 43744)):
#0  0x00000000009da906 in rec_offs_get_n_alloc (offsets=0x7fdf9c015118) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/include/rem0rec.ic:909
#1  rec_offs_n_fields (offsets=0x7fdf9c015118) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/include/rem0rec.ic:944
#2  rec_offs_validate (offsets=0x7fdf9c015118, index=0x0, rec=0x0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/include/rem0rec.ic:961
#3  rec_offs_extra_size (offsets=0x7fdf9c015118) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/include/rem0rec.ic:1486
#4  0x00000000009df0ca in page_cur_insert_rec_low (current_rec=0x7fdfb06f6b0b "", index=index@entry=0x7fdf9c01dd58, rec=rec@entry=0x7fdf9c01510d "", offsets=0x7fdf9c015118, mtr=mtr@entry=0x7fdfc02bc950)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/page/page0cur.c:984
#5  0x00000000008f3746 in page_cur_tuple_insert (cursor=cursor@entry=0x7fdfc02bce48, tuple=tuple@entry=0x7fdf9c01dbc8, index=index@entry=0x7fdf9c01dd58, n_ext=0, mtr=mtr@entry=0x7fdfc02bc950)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/include/page0cur.ic:267
#6  0x00000000008fa59e in btr_cur_optimistic_insert (flags=flags@entry=0, cursor=cursor@entry=0x7fdfc02bce40, entry=entry@entry=0x7fdf9c01dbc8, rec=rec@entry=0x7fdfc02bce38, big_rec=big_rec@entry=0x7fdfc02bce30,
    n_ext=n_ext@entry=0, thr=thr@entry=0x7fdf9c01ee58, mtr=mtr@entry=0x7fdfc02bc950) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/btr/btr0cur.c:1443
#7  0x0000000000a0f014 in row_ins_index_entry_low (mode=mode@entry=2, index=index@entry=0x7fdf9c01dd58, entry=entry@entry=0x7fdf9c01dbc8, n_ext=n_ext@entry=0, thr=thr@entry=0x7fdf9c01ee58)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/row/row0ins.c:2241
#8  0x0000000000a131c0 in row_ins_index_entry (index=0x7fdf9c01dd58, entry=<optimized out>, n_ext=n_ext@entry=0, foreign=foreign@entry=1, thr=thr@entry=0x7fdf9c01ee58)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/row/row0ins.c:2353
#9  0x0000000000a13dc0 in row_ins_index_entry_step (thr=0x7fdf9c01ee58, node=0x7fdf9c01e9b0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/row/row0ins.c:2441
#10 row_ins (thr=0x7fdf9c01ee58, node=0x7fdf9c01e9b0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/row/row0ins.c:2573
#11 row_ins_step (thr=thr@entry=0x7fdf9c01ee58) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/row/row0ins.c:2690
#12 0x000000000086beb6 in row_insert_for_mysql (mysql_rec=<optimized out>, prebuilt=0x7fdf9c01e488) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/row/row0mysql.c:1252
#13 0x000000000083ded8 in ha_innobase::write_row (this=0x7fdf9c018ce0, record=0x7fdf9c01c010 "\377\313\316\001")
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/storage/innobase/handler/ha_innodb.cc:6624
#14 0x00000000006e010a in handler::ha_write_row (this=0x7fdf9c018ce0, buf=0x7fdf9c01c010 "\377\313\316\001") at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/handler.cc:5507
#15 0x00000000006127f8 in copy_data_between_tables (error_if_not_empty=false, keys_onoff=<optimized out>, deleted=<synthetic pointer>, copied=<synthetic pointer>, order=0x0, order_num=0, ignore=<optimized out>,
    create=..., to=0x7fdf9c011390, from=0x7fdf9c00a680) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_table.cc:7493
#16 mysql_alter_table (thd=thd@entry=0x2a5d9a0, new_db=<optimized out>, new_name=0x7fdf9c004cb8 "sbtest1", create_info=create_info@entry=0x7fdfc02bed10, table_list=table_list@entry=0x7fdf9c004cf0,
    alter_info=alter_info@entry=0x7fdfc02bec50, order_num=0, order=0x0, ignore=false) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_table.cc:6796
#17 0x00000000007f5100 in Alter_table_statement::execute (this=<optimized out>, thd=0x2a5d9a0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_alter.cc:122
#18 0x00000000005a4fd6 in mysql_execute_command (thd=thd@entry=0x2a5d9a0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:5095
#19 0x00000000005a6537 in mysql_parse (thd=thd@entry=0x2a5d9a0, rawbuf=rawbuf@entry=0x7fdf9c004bf0 "alter table sbtest1 add col_test int", length=length@entry=36, parser_state=parser_state@entry=0x7fdfc02c05e0)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:6467
#20 0x00000000005a71ab in wsrep_mysql_parse (thd=thd@entry=0x2a5d9a0, rawbuf=0x7fdf9c004bf0 "alter table sbtest1 add col_test int", length=36, parser_state=parser_state@entry=0x7fdfc02c05e0)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:6271
#21 0x00000000005a87ad in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x2a5d9a0, packet=packet@entry=0x2aec691 "alter table sbtest1 add col_test int", packet_length=packet_length@entry=36)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:1245
#22 0x00000000005aabf4 in do_command (thd=0x2a5d9a0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:874
#23 0x0000000000658517 in do_handle_one_connection (thd_arg=thd_arg@entry=0x2a5d9a0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_connect.cc:1438
#24 0x000000000065874d in handle_one_connection (arg=0x2a5d9a0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_connect.cc:1346
#25 0x00007fdfd418a0a2 in start_thread () from /usr/lib/libpthread.so.0
#26 0x00007fdfd29ea49d in clone () from /usr/lib/libc.so.6

Thread 3 (Thread 0x7fdfc0280700 (LWP 43768)):
#0  0x00007fdfd418e03f in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
#1  0x00007fdfd1a7c745 in wait (this=0x7fdfc027d500, cond=...) at galerautils/src/gu_lock.hpp:56
#2  galera::Monitor<galera::ReplicatorSMM::CommitOrder>::enter (this=this@entry=0x2336610, obj=...) at galera/src/monitor.hpp:121
#3  0x00007fdfd1a76b28 in galera::ReplicatorSMM::pre_commit (this=0x2335b70, trx=0x7fdf94011920, meta=<optimized out>) at galera/src/replicator_smm.cpp:801
#4  0x00007fdfd1a893bf in galera_pre_commit (gh=<optimized out>, conn_id=4, trx_handle=<optimized out>, flags=<optimized out>, meta=0x2af2400) at galera/src/wsrep_provider.cpp:449
#5  0x000000000067f687 in wsrep_run_wsrep_commit (thd=thd@entry=0x2af07d0, hton=hton@entry=0x23c0360, all=all@entry=false)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/wsrep_hton.cc:431
#6  0x0000000000680408 in wsrep_prepare (hton=0x23c0360, thd=0x2af07d0, all=<optimized out>) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/wsrep_hton.cc:158
#7  0x00000000006da87d in ha_commit_trans (thd=thd@entry=0x2af07d0, all=all@entry=false) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/handler.cc:1384
#8  0x00000000006676bd in trans_commit_stmt (thd=thd@entry=0x2af07d0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/transaction.cc:383
#9  0x00000000005a522f in mysql_execute_command (thd=thd@entry=0x2af07d0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:5149
#10 0x00000000005a6537 in mysql_parse (thd=thd@entry=0x2af07d0, rawbuf=rawbuf@entry=0x7fdf94004bf0 "insert into uid(keycode,uid,poid,createtime) values(\"testCode1\",\"user112\",112,now())",
    length=length@entry=84, parser_state=parser_state@entry=0x7fdfc027f5e0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:6467
#11 0x00000000005a71ab in wsrep_mysql_parse (thd=thd@entry=0x2af07d0, rawbuf=0x7fdf94004bf0 "insert into uid(keycode,uid,poid,createtime) values(\"testCode1\",\"user112\",112,now())", length=84,
    parser_state=parser_state@entry=0x7fdfc027f5e0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:6271
#12 0x00000000005a87ad in dispatch_command (command=command@entry=COM_QUERY, thd=thd@entry=0x2af07d0,
    packet=packet@entry=0x2af4161 "insert into uid(keycode,uid,poid,createtime) values(\"testCode1\",\"user112\",112,now())", packet_length=packet_length@entry=84)
    at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:1245
#13 0x00000000005aabf4 in do_command (thd=0x2af07d0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_parse.cc:874
#14 0x0000000000658517 in do_handle_one_connection (thd_arg=thd_arg@entry=0x2af07d0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_connect.cc:1438
#15 0x000000000065874d in handle_one_connection (arg=0x2af07d0) at /media/Tintin/Work/code/percona-xtradb-cluster/trunk-25/Percona-Server/sql/sql_connect.cc:1346
#16 0x00007fdfd418a0a2 in start_thread () from /usr/lib/libpthread.so.0
#17 0x00007fdfd29ea49d in clone () from /usr/lib/libc.so.6


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The insert query is hung in ::pre_commit