DB deadlock

This Spring Boot project shows how the deadlock in database can occur when data are written into 2 tables simultaneously and how can be prevented by locking the tables. Application doesn't do much - run JUnit tests to observe.

Prerequisites

• Docker and Docker Compose
• Java
• Maven

Compiling and running the project

Run and setup MS SQL DB:

docker-compose up

Compile and run JUnit tests:

mvn clean test

All tests should pass. Check the difference between DbDeadLockingServiceTest.writeBothOppositeOrderAlphaBeta and DbNotDeadLockingServiceTest.writeBothOppositeOrderAlphaBeta - same test but one throws DB deadlock exception, the other one does not.

Cleanup:

docker-compose down

References

• MS SQL TABLOCKX - MS SQL documentation for locking the tables