1Demonstrations of mysqld_qslower, the Linux eBPF/bcc version. 2 3 4mysqld_qslower traces queries served by a MySQL server, and prints those that 5exceed a latency (query time) threshold. By default a threshold of 1 ms is 6used. For example: 7 8# ./mysqld_qslower.py `pgrep -n mysqld` 9Tracing MySQL server queries for PID 14371 slower than 1 ms... 10TIME(s) PID MS QUERY 110.000000 18608 130.751 SELECT * FROM words WHERE word REGEXP '^bre.*n$' 122.921535 18608 130.590 SELECT * FROM words WHERE word REGEXP '^alex.*$' 134.603549 18608 24.164 SELECT COUNT(*) FROM words 149.733847 18608 130.936 SELECT count(*) AS count FROM words WHERE word REGEXP '^bre.*n$' 1517.864776 18608 130.298 SELECT * FROM words WHERE word REGEXP '^bre.*n$' ORDER BY word 16 17This traced 5 queries, 4 of which took about 130 milliseconds. 18 19A pgrep command was used to specify the PID of mysqld. 20 21 22In this example, a lower threshold is used of 0.1 ms: 23 24# ./mysqld_qslower.py `pgrep -n mysqld` 0.1 25Tracing MySQL server queries for PID 14371 slower than 0.1 ms... 26TIME(s) PID MS QUERY 270.000000 18608 24.201 SELECT COUNT(*) FROM words 2813.242390 18608 130.378 SELECT * FROM words WHERE word REGEXP '^bre.*n$' 2923.601751 18608 119.198 SELECT * FROM words WHERE word REGEXP '^zzzzzzzz$' 30 31It worked, but I'm not catching any faster queries in this example. Notice I 32added a query that searched for "zzzzzzzz": it returned an empty set, and ran 3311 ms faster. 34 35 36A 0 ms threshold can be specified to trace all queries: 37 38# ./mysqld_qslower.py `pgrep -n mysqld` 0 39Tracing MySQL server queries for PID 14371 slower than 0 ms... 40TIME(s) PID MS QUERY 410.000000 18608 0.105 select @@version_comment limit 1 422.049312 18608 0.099 SELECT DATABASE() 432.050666 18608 0.274 show databases 442.051040 18608 0.176 show tables 455.730044 18608 130.365 SELECT count(*) AS count FROM words WHERE word REGEXP '^bre.*n$' 469.273837 18608 0.096 select 1 479.553742 18608 0.059 select 1 489.986087 18608 0.080 select 1 49 50This includes an initialization of a mysql client command, and selecting the 51database. I also added some "select 1;" queries, which do no work and return 52quickly. 53 54 55USAGE: 56 57# ./mysqld_qslower.py -h 58USAGE: mysqld_latency PID [min_ms] 59