asmhatreandClaude Sonnet 5.5
357ba84e5c
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_01YPgGH6aMbSLANL3E2HHmS6
1.6 KiB
1.6 KiB
locking
Companion module for the ankurm.com article on optimistic vs pessimistic locking in Hibernate 7. Two threads, one
in-memory H2 database, plain Hibernate (no Spring). Each test writes what it observed to output/.
Versions
| Component | Version | Notes |
|---|---|---|
| Hibernate ORM | 7.4.14.Final |
latest 7.x GA on Maven Central on 2026-10-25 (8.0.0.Beta3 is also listed; it is not GA) |
| Jakarta Persistence | 3.2.0 |
|
| H2 | 2.4.240 |
in memory, OPTIMIZE_REUSE_RESULTS=0 (see Db.java) |
| JUnit Jupiter / AssertJ | 6.0.3 / 3.27.7 |
|
| Java | 25 (Temurin 25.0.5+8) |
This module has its own pom.xml and does not use the Spring Boot parent of the main hibernate-demo project.
All locking behaviour here is H2's. SKIP LOCKED, NOWAIT and deadlock handling differ between databases, so check
your own.
Run
./scripts/run-all.sh
Output
| File | What it shows |
|---|---|
01-lost-update.txt |
two transactions read 100, both deposit, one deposit is lost (no @Version) |
02-version-stops-it.txt |
the same race with @Version: the second commit fails with OptimisticLockException |
03-retry-loop.txt |
six threads, thirty increments, retry on OptimisticLockException; the final balance is exact |
04-pessimistic-write.txt |
PESSIMISTIC_WRITE makes the second transaction wait; SQL uses for update |
05-no-wait.txt |
Timeouts.NO_WAIT fails at once (for update nowait) |
06-skip-locked.txt |
two workers claim different tickets (for update skip locked) |
07-deadlock.txt |
opposite lock order deadlocks; the same order for everyone does not |