Bug#29915479 RUNNING COM_REGISTER_SLAVE WITHOUT COM_BINLOG_DUMP CAN RESULTS IN SERVER EXIT

in fact, in MariaDB it cannot, but it can show spurious slaves in SHOW SLAVE HOSTS. slave was registered in COM_REGISTER_SLAVE and un-registered after COM_BINLOG_DUMP. If there was no COM_BINLOG_DUMP, it would never unregister.

Author: vuvova

mysql-test/suite/rpl/r/rpl_fail_register.result

@@ -0,0 +1,16 @@
+include/master-slave.inc
+[connection master]
+set @old_dbug=@@global.debug_dbug;
+set global debug_dbug='d,fail_com_register_slave';
+stop slave;
+reset slave;
+include/wait_for_slave_to_stop.inc
+start slave;
+stop slave;
+include/wait_for_slave_to_stop.inc
+set global debug_dbug=@old_dbug;
+kill DUMP_THREAD;
+show slave hosts;
+Server_id	Host	Port	Master_id
+start slave;
+include/rpl_end.inc

mysql-test/suite/rpl/t/rpl_fail_register.test

@@ -0,0 +1,33 @@
+source include/have_debug.inc;
+source include/have_binlog_format_mixed.inc;
+source include/master-slave.inc;
+
+connection slave;
+
+set @old_dbug=@@global.debug_dbug;
+set global debug_dbug='d,fail_com_register_slave';
+
+stop slave;
+reset slave;
+source include/wait_for_slave_to_stop.inc;
+start slave;
+stop slave;
+source include/wait_for_slave_to_stop.inc;
+set global debug_dbug=@old_dbug;
+
+connection master;
+
+### why is that needed?
+let $id=`SELECT id from information_schema.processlist where command='Binlog Dump'`;
+if ($id) {
+ replace_result $id DUMP_THREAD;
+ eval kill $id;
+ let $wait_condition= SELECT count(*)=0 from information_schema.processlist where command='Binlog Dump';
+ source include/wait_condition.inc;
+}
+
+show slave hosts;
+
+connection slave;
+start slave;
+source include/rpl_end.inc;

sql/slave.cc

@@ -3179,6 +3179,7 @@ pthread_handler_t handle_slave_io(void *arg)
  goto err;
  goto connected;
  }
+ DBUG_EXECUTE_IF("fail_com_register_slave", goto err;);
  }
 
  DBUG_PRINT("info",("Starting reading binary log from master"));

sql/sql_class.cc

@@ -63,6 +63,7 @@
 #include "sql_parse.h" // is_update_query
 #include "sql_callback.h"
 #include "sql_connect.h"
+#include "repl_failsafe.h"
 
 /*
  The following is used to initialise Table_ident with a internal
@@ -1496,6 +1497,7 @@ THD::~THD()
  if (rli_slave)
  rli_slave->cleanup_after_session();
  my_free(semisync_info);
+ unregister_slave(this, true, true);
 #endif
 
  free_root(&main_mem_root, MYF(0));

sql/sql_parse.cc

@@ -1269,7 +1269,6 @@ bool dispatch_command(enum enum_server_command command, THD *thd,
  general_log_print(thd, command, "Log: '%s' Pos: %lu", name, pos);
  if (nlen < FN_REFLEN)
  mysql_binlog_send(thd, thd->strmake(name, nlen), (my_off_t)pos, flags);
- unregister_slave(thd,1,1);
  /* fake COM_QUIT -- if we get here, the thread needs to terminate */
  error = TRUE;
  break;