[MDEV-14843] Assertion `s_tx_list.size() == 0' failed in myrocks::Rdb_transaction::term_mutex Created: 2018-01-01  Updated: 2018-03-28  Resolved: 2018-03-26

Status: Closed
Project: MariaDB Server
Component/s: Storage Engine - RocksDB
Affects Version/s: 10.2
Fix Version/s: 10.2.14

Type: Bug Priority: Major
Reporter: Elena Stepanova Assignee: Sergei Petrunia
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-15686 Loading MyRocks plugin back after it ... Closed
Sprint: 10.3.6-1

 Description    

--source include/have_log_bin.inc
 
--source include/have_binlog_format_row.inc
 
 
 
INSTALL SONAME 'ha_rocksdb';
 
CREATE TABLE t1 (i INT) ENGINE=RocksDB;
 
ALTER TABLE t1 FORCE;
 
 
 
# Cleanup
 
DROP TABLE t1;
 
UNINSTALL SONAME 'ha_rocksdb';

10.2 aed2050e40cb332d54e8d40eb7242309b962c4e1

 
mysqld: /data/src/10.2/storage/rocksdb/ha_rocksdb.cc:1838: static void myrocks::Rdb_transaction::term_mutex(): Assertion `s_tx_list.size() == 0' failed.
 
180101 16:24:37 [ERROR] mysqld got signal 6 ;
 
 
 
#7  0x00007f8b570b4ee2 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
 
#8  0x00007f8b509643f7 in myrocks::Rdb_transaction::term_mutex () at /data/src/10.2/storage/rocksdb/ha_rocksdb.cc:1838
 
#9  0x00007f8b5093d3e7 in myrocks::rocksdb_done_func (p=0x0) at /data/src/10.2/storage/rocksdb/ha_rocksdb.cc:4422
 
#10 0x00005608bfbdc7ea in ha_finalize_handlerton (plugin=0x5608c2a90908) at /data/src/10.2/sql/handler.cc:468
 
#11 0x00005608bf982979 in plugin_deinitialize (plugin=0x5608c2a90908, ref_check=true) at /data/src/10.2/sql/sql_plugin.cc:1214
 
#12 0x00005608bf982de6 in reap_plugins () at /data/src/10.2/sql/sql_plugin.cc:1290
 
#13 0x00005608bf9861c8 in mysql_uninstall_plugin (thd=0x7f8b34000b00, name=0x7f8b34005248, dl_arg=0x7f8b34005258) at /data/src/10.2/sql/sql_plugin.cc:2328
 
#14 0x00005608bf9736f8 in mysql_execute_command (thd=0x7f8b34000b00) at /data/src/10.2/sql/sql_parse.cc:6125
 
#15 0x00005608bf978568 in mysql_parse (thd=0x7f8b34000b00, rawbuf=0x7f8b340125e8 "UNINSTALL SONAME 'ha_rocksdb'", length=29, parser_state=0x7f8b51346200, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:7900
 
#16 0x00005608bf966476 in dispatch_command (command=COM_QUERY, thd=0x7f8b34000b00, packet=0x7f8b34008a41 "UNINSTALL SONAME 'ha_rocksdb'", packet_length=29, is_com_multi=false, is_next_command=false) at /data/src/10.2/sql/sql_parse.cc:1805
 
#17 0x00005608bf964dd4 in do_command (thd=0x7f8b34000b00) at /data/src/10.2/sql/sql_parse.cc:1360
 
#18 0x00005608bfab2c99 in do_handle_one_connection (connect=0x5608c2c66b50) at /data/src/10.2/sql/sql_connect.cc:1335
 
#19 0x00005608bfab2a26 in handle_one_connection (arg=0x5608c2c66b50) at /data/src/10.2/sql/sql_connect.cc:1241
 
#20 0x00005608bfed1de2 in pfs_spawn_thread (arg=0x5608c2bb1b40) at /data/src/10.2/storage/perfschema/pfs.cc:1863
 
#21 0x00007f8b58d8b494 in start_thread (arg=0x7f8b51347700) at pthread_create.c:333
 
#22 0x00007f8b5717193f in clone () from /lib/x86_64-linux-gnu/libc.so.6



 Comments   
Comment by Sergei Petrunia [ 2018-03-21 ]

One can change ALTER TABLE t1 FORCE; to any other statement that starts a MyRocks transaction, for example insert into t1 values (1);

Comment by Sergei Petrunia [ 2018-03-22 ]

Ok, the failing assert shows that a MyRocks transaction remains in the global MyRocks transaction list ( s_tx_list) when the plugin is unloaded.

MyRocks keeps a per-thread Rdb_transaction object. The object remains allocated even if there is no real active transaction.

This is a patch to remove an active transaction from the current thread: https://gist.github.com/spetrunia/a74cef1272c9e8a42114d13eefed7d9c .

The original testcase for this bug does not crash with this patch.

However, one can easily construct a slightly modified testcase which will still cause the same assertion failure:

--source include/have_log_bin.inc
 
--source include/have_binlog_format_row.inc
 
 
INSTALL SONAME 'ha_rocksdb';
 
CREATE TABLE t1 (i INT) ENGINE=RocksDB;
 
#ALTER TABLE t1 FORCE;
 
insert into t1 values (1);
 
 
 
connect (con1,localhost,root,,);
 
connection con1;
 
insert into test.t1 values (1);
 
 
 
connection default;
 
 
 
# Cleanup
 
DROP TABLE t1;
 
UNINSTALL SONAME 'ha_rocksdb';

Comment by Sergei Petrunia [ 2018-03-26 ]

If one adjusts the testcase to work with Percona Server, it will crash it, too: https://gist.github.com/spetrunia/48175603a1b6d38df7aecaad3fc3023b
Upstream is not affected because they link statically.

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