Frozen insertion in parallel transaction - mysql

Question

I have two transactions with shareable count down latch. Each transaction is performed in separate thread. I need such mechanism to reproduce "dirty read" situation.
The first transaction do update of "target entity" and flush changes without commit, then I set thread to waiting state (countDownLatch).
In the second transaction I fetch "target entity" and copy dirty field to another entity and do save. After save operation I make countDown to continue the first transaction and rollback it.
Below the code samples of transaction methods.
The first:
#Transactional
public void updatePrice() {
log.info("Start price updating. Thread '{}'", Thread.currentThread().getName());
Collection<Product> products = productRepository.findAll();
products.forEach(this::updatePrice);
productRepository.saveAll(products);
entityManager.flush();
log.info("Flash changes and wait for order transaction");
try {
latch.await();
} catch (InterruptedException e) {
log.error("Something wrong");
Thread.currentThread().interrupt();
}
log.error("Rollback changes");
throw new RuntimeException("Unexpected exception");
}
The second: I have main service that is bounded by transaction and wrapper service on it to count down the latch.
Wrapper:
public void doOrder(Long productId, Long amount) {
log.info("Start do order. Thread '{}'", Thread.currentThread().getName());
orderService.doOrder(productId, amount);
log.info("Order transaction committed");
latch.countDown();
log.info("Finish order process");
}
Main service:
#Transactional
public void doOrder(Long productId, Long amount) {
Product product = productRepository.findById(productId).get();
log.info("Get product");
Order order = Order.builder().price(product.getPrice()).amount(amount).productId(new Long(productId)).build();
orderRepository.save(order);
log.info("Save order");
}
So, at the line
orderRepository.save(order);
the thread has became frozen. I see only insert statement in the logs.
But if I remove relation between 'order' and 'product', the insert doesn't become frozen.
I guess that there is deadlock on 'product' and countDownLatch. But this issue occurs only with mysql jdbc. If I switch onto postgres jdbc, then no issue there.
PS:
The first transaction executes following queries:
select * from product;
update product set price = ...
The second one executes:
select * from product where id = ...;
insert into product_order(product_id, amount, price) values (...)