Bug #110460 When the system file limit is exceeded, the error report is ambiguous

• Submitted: 22 Mar 2023 9:14
• Modified: 22 Mar 2023 14:25
• Reporter: peng gao
• Status: Unsupported
• Category: MySQL Server
• Severity: S3 (Non-critical)
• Version: 5.7.40
• OS: Any
• CPU Architecture: Any

[22 Mar 2023 9:14] peng gao

Description:
Hi:
  we os file limit fs.file-max=65535,sometime reach limit,mysqld return error Table  doesn't exist and error log no obvious error reported.
  An obvious error should be added,when check .frm file.
thanks.

How to repeat:

mysql client:
mysql> select version();
+------------+
| version()  |
+------------+
| 5.7.40-log |
+------------+
1 row in set (0.00 sec)

mysql> show variables like '%log_error_verbosity%';
+---------------------+-------+
| Variable_name       | Value |
+---------------------+-------+
| log_error_verbosity | 3     |
+---------------------+-------+
1 row in set (0.01 sec)

mysql> truncate table io;
Query OK, 0 rows affected (0.00 sec)

mysql> truncate table io;
Query OK, 0 rows affected (0.00 sec)

mysql> truncate table io;
Query OK, 0 rows affected (0.00 sec)

mysql> truncate table io;
Query OK, 0 rows affected (0.00 sec)

change os file-max 

vi /etc/sysctl.conf  add fs.file-max = 128
sysctl -p

back to mysql client

mysql> truncate table io;
ERROR 1146 (42S02): Table 'mytest.io' doesn't exist
mysql> drop table io;
ERROR 1051 (42S02): Unknown table 'mytest.io'

check mysql error log，no obvious error reported.

Suggested fix:
diff --git a/D:/mysqlsorce/mysqlsource/mysql-5.7.40/sql/datadict.cc b/D:/mysqlsorce/sourceb/mysql-5.7.40/sql/datadict.cc
index 1090f50..8389eb7 100644
--- a/D:/mysqlsorce/mysqlsource/mysql-5.7.40/sql/datadict.cc
+++ b/D:/mysqlsorce/sourceb/mysql-5.7.40/sql/datadict.cc
@@ -26,6 +26,7 @@

 #include "pfs_file_provider.h"
 #include "mysql/psi/mysql_file.h"
+#include "log.h"

 /**
   Check type of .frm if we are not going to parse it.
@@ -49,7 +50,9 @@ frm_type_enum dd_frm_type(THD *thd, char *path, enum legacy_db_type *dbt)
   *dbt= DB_TYPE_UNKNOWN;

   if ((file= mysql_file_open(key_file_frm, path, O_RDONLY | O_SHARE, MYF(0))) < 0)
-    DBUG_RETURN(FRMTYPE_ERROR);
+    {sql_print_error("Error in open frm file: %s, %s", path,strerror(errno));
+     DBUG_RETURN(FRMTYPE_ERROR);}
+
   error= mysql_file_read(file, (uchar*) header, sizeof(header), MYF(MY_NABP));
   mysql_file_close(file, MYF(MY_WME));

2023-03-22T07:41:26.995765Z 2 [ERROR] Error in open frm file: ./t2/myt.frm, Too many open files in system
2023-03-22T07:41:36.834439Z 2 [ERROR] Error in open frm file: ./t2/myt.frm, Too many open files in system

[22 Mar 2023 13:58] MySQL Verification Team

Hi Mr. gao,

Thank you for your bug report.

However, 5.7 is in the maintenance state. Hence, it receives only fixes for the crashing and security bugs.

Changing error messages is not among them.

Unsupported.

[22 Mar 2023 14:25] peng gao

Thanks.