This document discusses deadlocks in JMeter and how to prevent them. Deadlocks occur when multiple threads or processes simultaneously try to access the same resource. The document provides an example SQL statement that could cause a deadlock and discusses how tools in JMeter like the JDBC Sampler could potentially cause deadlocks. It also presents strategies for avoiding deadlocks like ensuring thread counts match the number of users and transactions commit sequentially rather than simultaneously.

1. Prevent
deadlocks with
JMeter
O l e k s i i Z o z u l e n k o
automated-testing.info

2. History

3. deadlock - is ... ?
Не разрешимая
ситуация, которая
возникает при попытке
одновременно получить
доступ к одному
ресурсу с нескольких
потоков или источников

4. 5%
15%
80%
Database
Threads Sync
Others

5. Example

6. UPDATE products AS p, products AS pp
SET p.is_low_on_stock =
IFNULL(p.products_low_stock_level,
IFNULL(pp.products_low_stock_level,
0)) >= p.products_quantity,
pp.is_low_on_stock =
IFNULL(p.products_low_stock_level,
IFNULL(pp.products_low_stock_level,
0)) >= p.products_quantity WHERE
p.products_parent = pp.products_id AND
pp.products_id IN (5000, 10529);

7. Tools

8. Tools

9. Tools
JDBC Sampler
BSF Sampler
Your Own Sampler

10. Assume Causes

11. SELECT p.is_low_on_stock,
p.products_low_stock_level,
p.products_quantity, pp.is_low_on_stock
FROM products AS p, products AS pp
WHERE p.products_parent =
pp.products_id AND pp.products_id IN
(5000, 10529);
INSERT into products(product_id,
product_title, is_low_on_stock,
products_low_stock_level) values (NULL,
‘sometitle’, 5,0);

13. Users = Requests

14. Failure Example

19. Thanks
Oleksii Zozulenko
ozozulenko@gmail.com
automated-testing.info