Troubleshooting of tool failure caused by Chinese characters in PT kill query

The production environment encountered several YearningSQL Slow queries triggered by the platform （ The sql The resulting Cartesian product is too large , There is no result , R & D triggers the query again in the front-end interface ）, Finally, the database CPU Dragging up .

DBA After emergency intervention , according to mysql Server show full processlist Grab relevant sql, The execution time has exceeded 120s. First record the scene , then kill Drop the correlation query.

query It's like this ：

select 
aa AS A Column ,
bb as B Column 
FROM sbtest.sbtest1
where aa = 'abcdefg'
order by update_time desc
LIMIT 100;

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Compare the background operation logs , Confirm that this is where the R & D students are YearningSQL The query interface is submitted many times query.

however , We went online a few months ago pt-kill Timing task , Aim at YearningSQL The user query of the platform has done 60 Seconds of query timeout fuse . In theory, even if there is such a slow sql It will not take too long .

Look up the pt-kill Recent logs of , I found some hints ：

Wide character in print at pt-kill line 7373

Turn down the corresponding code segment , The following parts ：

According to the above sql, Basically, it can be judged that perl Encountered Chinese character processing failure during script execution .

Found the reason , The solution is simple ：

 stay pt-kill The file header , Add 2 Line code ：

use utf8;
use open ":encoding(utf8)",":std";

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In addition, for some complex queries , Some suggestions are given to R & D students ：

1、 It is recommended to explain Self assessment

2、 Querying , You can explicitly define 60 Second timeout , for example SELECT /*+ MAX_EXECUTION_TIME(60000) */ * FROM t1 INNER JOIN t2 WHERE ... 【5.7 And above 】