Details
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Bug
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Status: Closed (View Workflow)
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Blocker
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Resolution: Fixed
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10.5, 10.6, 10.2(EOL), 10.3(EOL), 10.4(EOL)
Description
row event execution starts from Rows_log_event::do_apply_event which calls open_and_lock_tables() which calls lock_tables(), which does
if (!(ptr=start=(TABLE**) thd->alloc(sizeof(TABLE*)*count))) |
thus allocating an array of points of the thd's memroot. This is just few bytes, 8 in the test below. But this memory is never freed, not by row events at least. So, by creating a transaction with a huge number of row events we can consume any amount of memory.
source include/have_innodb.inc;
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source include/have_binlog_format_row.inc;
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source include/master-slave.inc;
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create table t1 (a int) engine=innodb; |
insert t1 values (1); |
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sync_slave_with_master;
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stop slave;
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set global max_session_mem_used=10*1024*1024; |
start slave;
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connection master; |
let $a=1000000;
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start transaction; |
disable_query_log;
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while ($a) {
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update t1 set a=a+1; |
dec $a; |
}
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enable_query_log;
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commit; |
drop table t1; |
sync_slave_with_master;
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set global max_session_mem_used=default; |
source include/rpl_end.inc;
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To fix that, rbr events must do
free_root(thd->mem_root, MYF(MY_KEEP_PREALLOC));
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somewhere. Where it's safe, because it'll destroy anything allocated on the thd memroot.
This patch appears to be working fine, it frees thd memroot after closing all opened tables:
--- a/sql/rpl_rli.cc
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+++ b/sql/rpl_rli.cc
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@@ -2326,6 +2326,7 @@ void rpl_group_info::cleanup_context(THD *thd, bool error) |
*/
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reset_row_stmt_start_timestamp();
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unset_long_find_row_note_printed();
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+ free_root(thd->mem_root, MYF(MY_KEEP_PREALLOC));
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DBUG_EXECUTE_IF("inject_sleep_gtid_100_x_x", { |
if (current_gtid.domain_id == 100) |
Attachments
Issue Links
- relates to
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- Closed
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- mentioned in
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