pessimistic-locking

The Django documentation states that: If you were relying on “automatic transactions” to provide locking between select_for_update() and a subsequent write operation — an extremely fragile design, but nonetheless possible — you must wrap the relevant code in atomic(). Is the reason why this no longer works is that autocommit is done at the database layer and not the application layer? Previously the transaction would be held open until a data-altering function is called : Django’s default behavior is to run with an open transaction which it commits automatically when any built-in, data

i have spring project under java, using hibernate query, i like to use pessimistic locking. How to do Pessimistic locking in Spring + Hibernate? Edit: @Loggable(value = LogLevel.TRACE) @Transactional @Override public void updateBalance(String id, BigDecimal amount) { Session session = sessionFactory.getCurrentSession(); sessionFactory.openSession(); Transaction tx = session.beginTransaction(); session.flush(); Account acc = (Account) session.get(Account.class, id, LockMode.UPGRADE); acc.setName("New Account"); acc.setBalance(acc.getBalance().subtract(amount)); save(acc); try{ tx.commit();

i'm trying to figure out how to use/test the lockforupdate correctly, but i found is not function like what i expected this is just testing public function index() { return dd(\DB::transaction(function() { if (\Auth::guard('user')->check()) { $model = \App\Models\User::find(1)->lockForUpdate(); sleep(60); $model->point = 100000; $model->save(); } else { $model = \App\Models\User::find(1); $model->point = 999; $model->save(); } return $model; })); } i try to test in 2 browser, browser 1 user logged in and browser 2 not logged in, browser 1 hit refresh, then there will lockforupdate and sleep 60

I'm trying to implement some kind of semaphores for cron jobs that runs in different JBoss nodes. I'm trying to use the database (Oracle 11g) as a locking mechanism using one table to syncronize the cron jobs in the different nodes. The table is very simple: CREATE TABLE SYNCHRONIZED_CRON_JOB_TASK ( ID NUMBER(10) NOT NULL, CRONJOBTYPE VARCHAR2(255 Byte), CREATIONDATE TIMESTAMP(6) NOT NULL, RUNNING NUMBER(1) ); ALTER TABLE SYNCHRONIZED_CRON_JOB_TASK ADD CONSTRAINT PK_SYNCHRONIZED_CRON_JOB_TASK PRIMARY KEY (ID); So when a job starts it searches in the table for a entry of its cronjobtype, and

From some recent testing and reading I've done, it seems the "X" (exclusive) name part of XLOCK is misleading. It in fact doesn't lock any more than UPDLOCK. If it were exclusive, it would prevent external SELECTs, which it doesn't. I cannot see either from reading or from testing and difference between the two. The only time XLOCK creates an exclusive lock is when used with TABLOCK. My first question is "why only at this granularity?" Further, I came across a blog that states the following: However, watch out for XLOCK hint. SQL Server will effectively ignore XLOCK hint! There's an

I have a java project that runs on a webserver. I always hit this exception. I read some documentation, and found that pessimistic locking (or optimistic, but I read that pessimistic is better) is the best way to prevent this exception. But I couldn't find any clear example that explains how to use it. My method is like: @Transactional Public void test(Email email, String Subject){ getEmailById(String id); email.setSubject(Subject); updateEmail(email); } while: Email is a hibernate class (it will be a table in the database) getEmailById(String id) is a function that returns an email (this