MySQL Bugs: #42462: Query Browser crashes (or becomes very slow) displaying mediumtext fields

Bug #42462	Query Browser crashes (or becomes very slow) displaying mediumtext fields
Submitted:	29 Jan 2009 19:24	Modified:	4 Feb 2009 12:21
Reporter:	Leandro Morgado	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Query Browser	Severity:	S1 (Critical)
Version:	1.2.15	OS:	Windows (XP SP1,SP2)
Assigned to:	Mike Lischke	CPU Architecture:	Any

Description:
When displaying larger mediumtext fields in the Query Browser, it will slow down to a crawl or crash.

On my tests, it slowed down on a Quad-Core with 4Gb RAM and Vista.

Shane tested on Windows XP SP1 and the effects were more noticeable:

------------------------------------------------------------------
I noticed a nonresponsive moments as soon as the mediumtext field came into view.

Got no clue what QB does to render those fields, but it appears to be alot of work.
Guess you could try customer's test except click on "2" instead of "12". I got
a long freeze (about 10-15 second) where QB didn't respond and workation nearly died.

mysql> SELECT length(log_field) as len,id_job FROM kettle_repo_live_171.joblogging order by len desc;
+--------+--------+
| len | id_job |
+--------+--------+
| 352520 | 2 |
| 108493 | 7 |
| 68039 | 12 |
| 62264 | 14 |
| 42709 | 0 |
| 16605 | 9 |
| 12490 | 10 |
| 11064 | 8 |
| 10295 | 11 |
| 8456 | 3 |
| 8434 | 6 |
| 8348 | 5 |
| 8200 | 4 |
| NULL | 1 |
| NULL | 13 |
| NULL | 15 |
+--------+--------+
16 rows in set (0.02 sec)
------------------------------------------------------------------

How to repeat:
Import the attached test_data.zip file.

Do "SELECT * FROM kettle_repo_live_171.joblogging ;"

Select the value "12" in front of field jobname = ttccom112.

Press right to move on column to the right. Now "ttccom112" i selected.
Repeat this till you reach the last column.

You will probably never get there as the client becomes unresponsive.

obviously on a single-core workstation (like mine) the problem will be much worse. this is because that core is at 100% cpu. for a quad core, you still have three remaining cores to service the OS and GUI.

Thank you for your bug report. This issue has been committed to our source repository of that product and will be incorporated into the next release.

If necessary, you can access the source repository and build the latest available version, including the bug fix. More information about accessing the source trees is available at

    http://dev.mysql.com/doc/en/installing-source.html

Fixed in query-browser repository, revision 715