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This means that an unreleased lock in any thread will stop other threads from acquiring the same lock.

Noncompliant Code Example

This noncompliant code example protects a resource by using a ReentrantLock but on an exceptional condition, fails to release the lock. Control flow transfers to the catch block and the call to unlock() does not execute.

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Note that the lock is not released even when the doSomething() method returns.

Compliant Solution

This compliant solution uses a try-finally block immediately after acquiring the lock. This ensures that the lock is appropriately released even in the event of an exceptional condition.

public void doSomething() {
  final Lock lock = new ReentrantLock();
  lock.lock();
  try {
    // Do something with the protected resource
    // This may cause an exception such as FileNotFoundException
  } catch(FileNotFoundException fnf) {
    // Handle the exception
  } finally {
    lock.unlock();
  }
}

Risk Assessment

Failing to release a lock on an exceptional condition may lead to thread starvation and deadlock.

Automated Detection

TODO

Related Vulnerabilities

GERONIMO-2234

References

\[[API 06|AA. Java References#API 06]\] Class {{ReentrantLock}}

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