What is Lock Striping in Concurrent Programming?

By | March 7, 2023

Lock striping is a technique used in concurrent programming to improve performance in situations where many threads contend for access to a shared resource protected by a lock.

Instead of using a single lock to protect the entire resource, lock striping divides the resource into smaller sections, each with its own lock. Each thread that needs access to the resource only needs to acquire the lock for the specific section of the resource that it needs to access. This reduces contention for the locks and can lead to better performance.

In Java, the ConcurrentHashMap class uses lock striping to protect access to its internal hash table. The hash table is divided into a fixed number of segments, and each segment is protected by its own lock. When a thread needs to access a particular element in the hash table, it only needs to acquire the lock for the corresponding segment, rather than the entire hash table.

Here is an example of how to lock striping can be implemented using the Java ReentrantLock class:

import java.util.concurrent.locks.ReentrantLock;

public class Example {
private final int numStripes = 16;
private final ReentrantLock[] locks = new ReentrantLock[numStripes];
private final Object[] data = new Object[numStripes];

public Example() {
for (int i = 0; i < numStripes; i++) {
locks[i] = new ReentrantLock();
data[i] = new Object();

public void doSomething(int index) {
int stripeIndex = index % numStripes;
try {
// Access data[index] here
} finally {

In this example, the Example class has an array of locks and an array of data elements. The doSomething method takes an index parameter and uses lock striping to access the corresponding data element. The stripeIndex variable is calculated by taking the modulus of the index with the number of stripes, and the lock for the corresponding stripe is acquired using locks[stripeIndex].lock(). The data element is accessed inside the lock, and then the lock is released using locks[stripeIndex].unlock().

Note that lock striping is not always the best solution for improving concurrency performance. It can increase memory usage and add overhead due to the need to acquire multiple locks. The effectiveness of lock striping depends on the specific use case and the number of threads contending for access to the shared resource.

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