What is a memory leak?
💡 Concept: Memory Leak
A memory leak in C# occurs when the application holds references to objects that are no longer needed, preventing the garbage collector from reclaiming memory.
📘 Quick Intro
Memory leaks lead to increased memory consumption, reduced application performance, and potential crashes if unmanaged.
🧠 Analogy
Imagine holding onto old files in your desk forever, even if you no longer need them, cluttering the workspace.
🔧 Technical Explanation
- 🗑️ Objects still referenced are not collected by the garbage collector.
- 🔗 Common causes: event handlers not detached, static references, circular references in unmanaged code.
- 📉 Leads to memory bloat and performance degradation.
- 🛠️ Use profiling tools to detect leaks.
- 🔄 Best practice is to release references and unsubscribe from events.
🎯 Use Cases
- ✅ Diagnosing performance issues in long-running apps.
- ✅ Ensuring proper disposal of event subscriptions.
- ✅ Preventing out-of-memory exceptions.
- ✅ Writing memory-efficient C# code.
💻 Code Example
// Event subscription causing memory leak if not unsubscribed
class Publisher {
public event EventHandler RaiseEvent;
}
class Subscriber {
public void Subscribe(Publisher pub) {
pub.RaiseEvent += HandleEvent;
}
private void HandleEvent(object sender, EventArgs e) { /*...*/ }
public void Unsubscribe(Publisher pub) {
pub.RaiseEvent -= HandleEvent;
}
}
❓ Interview Q&A
Q1: What is a memory leak?
A: Unreleased memory due to persistent references.
Q2: What causes memory leaks in C#?
A: Event handlers, static references, unmanaged resources.
Q3: How to detect memory leaks?
A: Using profiling and diagnostic tools.
Q4: How to prevent memory leaks?
A: Properly unsubscribe events and dispose objects.
Q5: Can garbage collection fix leaks?
A: No, GC only collects unreferenced objects.
Q6: What is event subscription leak?
A: Forgetting to unsubscribe keeps objects alive.
Q7: Is static reference a cause?
A: Yes, it keeps objects rooted.
Q8: Can unmanaged code cause leaks?
A: Yes, if not managed correctly.
Q9: What happens if memory leaks?
A: Performance degradation and crashes.
Q10: How to avoid leaks?
A: Follow best practices for resource management.
📝 MCQs
Q1. What is a memory leak?
- Released memory
- Unreleased memory
- Memory allocation
- Garbage collection
Q2. What causes memory leaks?
- Loops
- Event handlers and static references
- Threads
- Exceptions
Q3. How to detect memory leaks?
- Debug logs
- Profiling tools
- Unit tests
- Code review
Q4. How to prevent memory leaks?
- Ignore
- Unsubscribe events
- Use static
- Restart app
Q5. Can GC fix leaks?
- Yes
- No
- Sometimes
- Never
Q6. What is event subscription leak?
- Unsubscribing
- Not unsubscribing
- Garbage collecting
- Allocating
Q7. Is static reference a leak cause?
- No
- Yes
- Sometimes
- No idea
Q8. Can unmanaged code cause leaks?
- No
- Yes
- Sometimes
- No idea
Q9. What happens if memory leaks?
- Better performance
- Performance issues
- No effect
- Crash
Q10. How to avoid leaks?
- Ignore
- Proper resource management
- Use more memory
- Restart system
💡 Bonus Insight
Being aware of memory leaks and proactively managing event subscriptions and references is key to robust C# applications.
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