How to Deal with a Closed Entity Manager in Doctrine

3 min readOct 21, 2023

Introduction

if you’re delving into software engineering and working with Object-Relational Mapping (ORM) tools, especially in a Symfony-based project, you’re likely to encounter a pesky issue known as a “closed Entity Manager.” This isn’t just a minor inconvenience - it can halt your application’s workflow and throw a wrench into your development or production environment. This glitch is particularly common when transactions don’t go as planned or when an exception is thrown, leaving you scrambling to troubleshoot the problem. In this context, understanding why an Entity Manager closes and how to effectively handle it becomes crucial, not just for keeping your application up and running, but also for maintaining data integrity and application reliability.

Why Does the Entity Manager Close?

Before diving into the solutions, it’s crucial to understand why an Entity Manager might close. The reasons can be multifaceted, but generally, they fall into the following categories:

Transaction Failure: A failed transaction due to an exception or manual rollback leads to an Entity Manager closure. This is done to maintain data integrity and prevent the application from continuing in an inconsistent state.
Manual Closure: The Entity Manager can be manually closed using the EntityManager#close() method.
Concurrency Issues: In multi-threaded or asynchronous environments, the Entity Manager may be closed in one thread or process while it’s still being used in another, leading to unexpected behavior.

Strategies for Resolution

1. Check State

Before performing any operations, you can check the Entity Manager’s state to ensure it’s open.

if (!$entityManager->isOpen()) { // handle closed Entity Manager }

2. Reset Manager (Symfony Specific)

In Symfony, resetting the Entity Manager is straightforward thanks to the manager registry.

$newEntityManager = $managerRegistry->resetManager();

3. Create a New Manager Instance

Although not recommended, you can also instantiate a new Entity Manager manually. Be cautious while doing this, as configuring the manager appropriately is critical.

4. Transactional Boundaries

Another preventive measure is to use smaller, well-defined transactions. By keeping transactions concise and purposeful, you minimize the risk of transaction failure, which could close the Entity Manager.

5. Exception Handling

Surround your code blocks with try-catch statements to catch any exceptions that may lead to the Entity Manager’s closure.

try {
    // code that uses EntityManager
} catch (Exception $e) {
    // handle exception and decide whether to close or reset Entity Manager
}

6. Concurrency Control

For applications operating in multi-threaded environments, leverage concurrency control mechanisms like locks to prevent unexpected closure.

7. Defensive Programming

In high-risk code areas, apply defensive programming techniques to pre-empt issues that could lead to the Entity Manager closing.

8. Logging and Monitoring

Implement robust logging and monitoring solutions to track when and why the Entity Manager closes, aiding in future debugging.

Full Example

use Psr\Log\LoggerInterface;

class YourClass {
    private LoggerInterface $logger;

    public function __construct(LoggerInterface $logger) {
        $this->logger = $logger;
    }
    
    private function persistSomething(Something $something): void {
        $this->entityManager->persist($something);
        $this->entityManager->flush();
    }

    private function rollbackAndReset(): void {
        $this->entityManager->rollback();
        $this->managerRegistry->resetManager();
    }

    private function handleException(Something $something, \Throwable $exception): void {
        $this->logger->error('Entity Manager closed due to exception.', [
            'exception' => $exception->getMessage(),
            'trace' => $exception->getTraceAsString(),
        ]);

        $this->rollbackAndReset();

        $something->isErroneous();
        $something->setErrorMessage($exception->getMessage());

        $this->persistSomething($something);
    }

    public function execute(): void {
        $something = new Something();
        
        $this->entityManager->beginTransaction();
        
        try {
            $this->persistSomething($something);
            $this->entityManager->commit();
        } catch (\Throwable $exception) {
            $this->handleException($something, $exception);
            $this->entityManager->commit();
        }
    }
}

Conclusion

The Entity Manager’s closure can be a convoluted issue but understanding its root causes and implementing effective strategies can substantially mitigate its impact. From exception handling to transaction boundaries, each approach has its merits and applicability, depending on the specific requirements and constraints of your project.

Given the intricate landscape of financial technology and the architectural complexities it often involves, these strategies can be especially useful. So the next time you encounter a closed Entity Manager, you’ll be well-equipped to tackle it head-on.