Member-only story
Boost Java Performance: Use Concurrent Collections for Multi-Threading
Learn how Java’s ConcurrentHashMap, CopyOnWriteArrayList, and other concurrent collections prevent race conditions and improve multi-threaded performance. Includes best practices and examples.
🚀 Why Use Concurrent Collections in Multi-Threading?
In multi-threaded applications, using standard collections like ArrayList or HashMap can cause race conditions and data corruption.
❌ Traditional collections (ArrayList, HashMap) are NOT thread-safe
❌ Using synchronized slows down performance
❌ Manual locks (synchronized, Lock) make code complex and error-prone
💡 Solution? Concurrent Collections provide built-in thread safety without the need for explicit synchronization.
📌 In this article, you’ll learn:
✅ Why traditional collections fail in multi-threading
✅ How concurrent collections improve performance
✅ Complete examples for ConcurrentHashMap, CopyOnWriteArrayList, BlockingQueue, and more
🔍 The Problem: Standard Collections Are Not Thread-Safe
✔ Race Conditions with HashMap (Not Thread-Safe)
import java.util.HashMap;
import java.util.Map;
public class HashMapRaceCondition {
private static final Map<Integer, String> map = new HashMap<>();
public static void main(String[] args) {
Runnable task = () -> {
for (int i = 0; i < 1000; i++) {
map.put(i, "Value " + i); // ❌ Unsafe operation
}
};
Thread t1 = new Thread(task);
Thread t2 = new Thread(task);
t1.start();
t2.start();
}
}📌 Problems:
❌ Race condition: Multiple threads modifying HashMap simultaneously.
❌ Data corruption: Some entries might be lost or overwritten unexpectedly.
❌ Throws ConcurrentModificationException when iterating over a modified collection.
🚀 Solution? Use ConcurrentHashMap instead!
