| Bug #55289 | mysqlbinlog ignores errors while writing output | ||
|---|---|---|---|
| Submitted: | 15 Jul 2010 15:10 | Modified: | 31 May 2012 17:34 |
| Reporter: | Mark Callaghan | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Command-line Clients | Severity: | S2 (Serious) |
| Version: | 5.1.47 | OS: | Any |
| Assigned to: | Alfranio Junior | CPU Architecture: | Any |
| Tags: | error, IGNORE, mysqlbinlog | ||
[15 Jul 2010 15:15]
Domas Mituzas
The testcase:
===
#!/usr/bin/python
import os
os.popen("mysqlbinlog mysqld-relay-bin....")
===
(Same in other languages)
[15 Jul 2010 20:17]
Sveta Smirnova
Thank you for the report. Verified as described. To repeat I modified source: $bzr diff === modified file 'sql/log_event.cc' --- sql/log_event.cc 2010-05-19 23:50:42 +0000 +++ sql/log_event.cc 2010-07-15 20:08:29 +0000 @@ -2961,6 +2961,7 @@ print_query_header(&cache, print_event_info); my_b_write(&cache, (uchar*) query, q_len); +sleep(20); my_b_printf(&cache, "\n%s\n", print_event_info->delimiter); } #endif /* MYSQL_CLIENT */ Then run mysqlbinlog command: $mysqlbinlog master-bin.000001 -r bug55289.sql Then in another terminal issues rm bug55289.sql In first terminal mysqlbinlog was still running, then it finished I checked return value and got no error: $echo $? 0
[31 May 2012 17:34]
Paul DuBois
Noted in 5.1.64, 5.5.26, 5.6.6 changelogs. mysqlbinlog exited with no error code if file write errors occurred.
[26 Jan 2013 3:36]
Andrew Garner
This is not fixed - the check only verifies if the head_cache hit an error, but not the body cache, even in mysql-5.6.9-rc. This is trivially seen when writing to a full disk: # mysqlbinlog -r binlog.sql /var/lib/mysql/mysqld-bin.000193 mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) mysqlbinlog: Error writing file 'binlog.sql' (Errcode: 28) ... # echo $? 0 A patch that also verifies if &print_event_info->body_cache->error is set (along with head->error) fixes many more of the cases but I think this is still not a full fix.
Description: mysqlbinlog cannot be used in an automated fashion (shell, python or perl script) because it ignores errors while writing binlog events to stdout. As stdout may be a file, errors can occur while writing to it. Perhaps Domas will provide the test case. For now, read the code. How to repeat: The code does not support returning an error. From log_event.h, the print functions return nothing. /* print*() functions are used by mysqlbinlog */ virtual void print(FILE* file, PRINT_EVENT_INFO* print_event_info) = 0; From log_event.cc: void Query_log_event::print(FILE* file, PRINT_EVENT_INFO* print_event_info) { Write_on_release_cache cache(&print_event_info->head_cache, file); print_query_header(&cache, print_event_info); my_b_write(&cache, (uchar*) query, q_len); my_b_printf(&cache, "\n%s\n", print_event_info->delimiter); } From mysqlbinlog.cc: default: ev->print(result_file, print_event_info);