| Bug #98120 | using debug method cause mysqld crash with SEGV signal | ||
|---|---|---|---|
| Submitted: | 3 Jan 2020 8:18 | Modified: | 31 Jan 2020 13:49 |
| Reporter: | zhanghe zhang | Email Updates: | |
| Status: | Not a Bug | Impact on me: | |
| Category: | MySQL Server: Optimizer | Severity: | S6 (Debug Builds) |
| Version: | 8.0 | OS: | Ubuntu (19.10) |
| Assigned to: | CPU Architecture: | x86 | |
| Tags: | debug, Optimizer | ||
[3 Jan 2020 8:21]
zhanghe zhang
the patch fixed this issue
Attachment: fixed_crash.patch (text/x-patch), 1.12 KiB.
[3 Jan 2020 8:25]
zhanghe zhang
add version info: zhanghe@node3:~/database/mysql-server$ git branch -a * 8.0 remotes/origin/5.5 remotes/origin/5.6 remotes/origin/5.7 remotes/origin/8.0 remotes/origin/HEAD -> origin/8.0 remotes/origin/cluster-7.2 remotes/origin/cluster-7.3 remotes/origin/cluster-7.4 remotes/origin/cluster-7.5 remotes/origin/cluster-7.6 zhanghe@node3:~/database/mysql-se
[3 Jan 2020 8:39]
zhanghe zhang
modify os version
[27 Jan 2020 14:05]
MySQL Verification Team
Hi Mr. Zhang, I build my source tree with all debug options, but it runs just fine. I am not able to crash it at all. Hence, how can we repeat the crash ?????
[31 Jan 2020 13:25]
zhanghe zhang
hi, Sinisa Milivojevic! the original source tree hasn't problem, these code has been commented , in file sql_optimizer.cc:263, sql_optimizer.cc:269 of function dump_TABLE_LIST_graph , i think it's a very useful debug function, so subscribe this issue.
[31 Jan 2020 13:38]
MySQL Verification Team
Hi Mr. zhang, I must admit that I truly do not understand much of what you have written here. Second, if you are changing our source code, I have to set this bug to "Not a bug". We do not support MySQL server built from a changed source. We do however support our Plugin interfaces.
[31 Jan 2020 13:46]
zhanghe zhang
ok, now i understood this rule. please set it 'not a bug'.
[31 Jan 2020 13:49]
MySQL Verification Team
Thank you Mr. zhang, You are truly welcome to report bugs on our unchanged code. You can also file a feature request with your patch that would improve the functionality or speed of our software.
Description: in sql/sql_optimizer.cc:262 ,using dump_TABLE_LIST_graph() function dump parsed tree info, cause mysqld crashed: zhanghe@node3:~/database/mysql-server$ git diff sql/sql_optimizer.cc diff --git a/sql/sql_optimizer.cc b/sql/sql_optimizer.cc index 1879cdcb1ee..039f6e2b14d 100644 --- a/sql/sql_optimizer.cc +++ b/sql/sql_optimizer.cc @@ -260,7 +260,8 @@ bool JOIN::optimize() { // The base ref items from query block are assigned as JOIN's ref items ref_items[REF_SLICE_ACTIVE] = select_lex->base_ref_items; - /* dump_TABLE_LIST_graph(select_lex, select_lex->leaf_tables); */ + dump_TABLE_LIST_graph(select_lex, select_lex->leaf_tables); How to repeat: 1. compile source tree and set config option WITH_DEBUG=on shell> cmake -S mysql-server/ -B mysql-debug-8/ -DWITH_DEBUG=ON -DWITH_BOOST=/home/zhanghe/boost_1_70_0 -DWITH_SYSTEMD=ON -DOPTIMIZER_TRACE=1 -DCMAKE_INSTALL_PREFIX=/home/zhanghe/mysql 2. initilaize data dir and start mysql shell > cd /home/zhanghe/mysql; bin/mysqld & 3. crashed with SEGV Suggested fix: zhanghe@node3:~/database/mysql-server$ git diff sql/sql_test.cc diff --git a/sql/sql_test.cc b/sql/sql_test.cc index 02a4056d798..85fda77ad9f 100644 --- a/sql/sql_test.cc +++ b/sql/sql_test.cc @@ -553,7 +553,7 @@ void Dbug_table_list_dumper::dump_one_struct(TABLE_LIST *tbl) { if (tbl->nested_join) fprintf(out, "|<nested_j>nested_j=%p", tbl->nested_join); if (tbl->join_list) fprintf(out, "|<join_list>join_list=%p", tbl->join_list); - if (tbl->on_expr) fprintf(out, "|<on_expr>on_expr=%p", tbl->on_expr); + // if (tbl->on_expr) fprintf(out, "|<on_expr>on_expr=%p", tbl->on_expr); fprintf(out, "\"\n"); fprintf(out, " shape = \"record\"\n];\n\n"); @@ -615,6 +615,7 @@ int Dbug_table_list_dumper::dump_graph(SELECT_LEX *select_lex, TABLE_LIST *tbl; tables_fifo.reset(); + tbl_lists.reset(); dump_one_struct(first_leaf); while (tables_fifo.pop_first(&tbl)) { dump_one_struct(tbl); @@ -636,7 +637,7 @@ int Dbug_table_list_dumper::dump_graph(SELECT_LEX *select_lex, fputs("}", out); fclose(out); - char filename2[500]; + char filename2[506]; filename[strlen(filename) - 1] = 0; filename[strlen(filename) - 1] = 0; sprintf(filename2, "%s.query", filename);