BAEL-3855

Lock Striping

lock-striping/pom.xml

@@ -0,0 +1,43 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <groupId>com.baeldung.concurrent.lock</groupId>
+  <artifactId>lock-striping</artifactId>
+  <version>0.0.1-SNAPSHOT</version>
+  
+  <properties>
+      <jmh.version>1.21</jmh.version>
+      <guava.version>28.2-jre</guava.version>
+  </properties>
+    
+  <dependencies>
+	<dependency>
+	    <groupId>com.google.guava</groupId>
+	    <artifactId>guava</artifactId>
+	    <version>${guava.version}</version>
+	</dependency>	
+	<dependency>
+	    <groupId>org.openjdk.jmh</groupId>
+	    <artifactId>jmh-core</artifactId>
+	    <version>${jmh.version}</version>
+	</dependency>
+	<dependency>
+	    <groupId>org.openjdk.jmh</groupId>
+	    <artifactId>jmh-generator-annprocess</artifactId>
+	    <version>${jmh.version}</version>
+	</dependency>
+	
+  </dependencies>
+  <build>
+    <sourceDirectory>src</sourceDirectory>
+    <plugins>
+      <plugin>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>3.8.0</version>
+        <configuration>
+          <source>1.8</source>
+          <target>1.8</target>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

lock-striping/src/com/baeldung/concurrent/lock/BenchMark.java

@@ -0,0 +1,66 @@
+package com.baeldung.concurrent.lock;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+
+@State(Scope.Thread)
+@Warmup(iterations = 2, time = 1, timeUnit = TimeUnit.MILLISECONDS)
+@Measurement(iterations = 3, time = 1, timeUnit = TimeUnit.MILLISECONDS)
+public class BenchMark {
+    ConcurrentAccessMap accessMyMap;
+
+	@Param({"HashMap", "HashMap with Lock", "HashMap with Striped Lock", 
+		"ConcurrentHashMap", "ConcurrentHashMap with Lock", "ConcurrentHashMap with Striped Lock"})
+    private String type;
+		
+	@Setup
+    public void setup() {
+        switch (type) {
+            case "HashMap":
+                accessMyMap = new NoLock(getHashMap());
+                break;
+            case "ConcurrentHashMap":
+                accessMyMap = new NoLock(getConcurrentHashMap());
+                break;
+            case "HashMap with Lock":
+                accessMyMap = new CoarseGrained(getHashMap());
+                break;
+            case "ConcurrentHashMap with Lock":
+                accessMyMap = new CoarseGrained(getConcurrentHashMap());
+                break;
+            case "HashMap with Striped Lock":
+                accessMyMap = new LockStriped(getHashMap());
+                break;
+            case "ConcurrentHashMap with Striped Lock":
+                accessMyMap = new LockStriped(getConcurrentHashMap());
+                break;
+        }
+    }
+	
+	private Map<String, String> getHashMap() {
+		return new HashMap<String,String>();
+	}
+	
+	private Map<String, String> getConcurrentHashMap() {
+		return new ConcurrentHashMap<String,String>();
+	}
+	
+	@Benchmark
+	@BenchmarkMode(Mode.Throughput)
+	@OutputTimeUnit(TimeUnit.MILLISECONDS)
+	public void test() throws InterruptedException {
+        accessMyMap.doWork(type);
+	}
+}

lock-striping/src/com/baeldung/concurrent/lock/CoarseGrained.java

@@ -0,0 +1,39 @@
+package com.baeldung.concurrent.lock;
+
+import java.util.Map;
+import java.util.concurrent.locks.ReentrantLock;
+
+import com.google.common.base.Supplier;
+
+public class CoarseGrained extends ConcurrentAccessMap {
+	ReentrantLock lock;
+
+	public CoarseGrained(Map<String, String> map) {
+		super(map);
+		lock = new ReentrantLock();
+	}
+
+	protected Supplier<?> putSupplier(int x) {
+		return (()-> {
+			boolean done = false;
+			while(!done) {
+				done = lock.tryLock();
+			}	
+			map.put("key" + x, "value" + x);
+			lock.unlock();
+    		return null;
+		});
+	}
+	
+	protected Supplier<?> getSupplier(int x) {
+		return (()-> {
+			boolean done = false;
+			while(!done) {
+				done = lock.tryLock();
+			}
+			map.get("key" + x);
+			lock.unlock();
+    		return null;
+		});
+	}
+}

lock-striping/src/com/baeldung/concurrent/lock/ConcurrentAccessMap.java

@@ -0,0 +1,33 @@
+package com.baeldung.concurrent.lock;
+
+import java.util.Map;
+import java.util.concurrent.CompletableFuture;
+
+import com.google.common.base.Supplier;
+
+public abstract class ConcurrentAccessMap {
+	static final int SLOTS = 4;
+	static final int THREADS = 10000;
+	static final int BUCKETS = Runtime.getRuntime().availableProcessors() * SLOTS;
+	private CompletableFuture<?>[] requests;
+	Map<String, String> map;
+		
+	public ConcurrentAccessMap(Map<String, String> map) {
+		this.map = map;
+	}
+	
+	public final void doWork(String type) {
+		requests = new CompletableFuture<?>[THREADS * SLOTS];
+
+		for (int i = 0; i < THREADS; i++) {
+        	requests[SLOTS * i + 0] = CompletableFuture.supplyAsync(putSupplier(i));
+    		requests[SLOTS * i + 1] = CompletableFuture.supplyAsync(getSupplier(i));
+    		requests[SLOTS * i + 2] = CompletableFuture.supplyAsync(getSupplier(i));
+    		requests[SLOTS * i + 3] = CompletableFuture.supplyAsync(getSupplier(i)); 	
+		}
+		CompletableFuture.allOf(requests).join();
+	}
+		
+	protected abstract Supplier<?> putSupplier(int x);
+	protected abstract Supplier<?> getSupplier(int x);
+}

lock-striping/src/com/baeldung/concurrent/lock/LockStriped.java

@@ -0,0 +1,47 @@
+package com.baeldung.concurrent.lock;
+
+import java.util.Map;
+import java.util.concurrent.locks.Lock;
+
+import com.google.common.base.Supplier;
+import com.google.common.util.concurrent.Striped;
+
+public class LockStriped extends ConcurrentAccessMap {
+	Striped<Lock> lock;
+
+	public LockStriped(Map<String, String> map) {
+		super(map);
+		lock = getStripedLock();
+	}
+
+	private Striped<Lock> getStripedLock() {
+		Striped<Lock> map = Striped.lock(BUCKETS);
+		return map;
+	}
+	
+	protected Supplier<?> putSupplier(int x) {
+		return (()-> {
+			Lock currentLock = lock.get("key" + x);
+			boolean done = false;
+			while(!done) {
+				done = currentLock.tryLock();
+        	}
+    		map.put("key" + x, "value" + x);
+    		currentLock.unlock();
+    		return null;
+		});
+	}
+	
+	protected Supplier<?> getSupplier(int x) {
+		return (()-> {
+			Lock currentLock = lock.get("key" + x);
+			boolean done = false;
+			while(!done) {
+				done = currentLock.tryLock();
+        	}
+    		map.get("key" + x);
+    		currentLock.unlock();
+    		return null;
+		});
+	}
+}

lock-striping/src/com/baeldung/concurrent/lock/NoLock.java

@@ -0,0 +1,34 @@
+package com.baeldung.concurrent.lock;
+
+import java.util.Map;
+
+import com.google.common.base.Supplier;
+
+public class NoLock extends ConcurrentAccessMap {
+	
+	public NoLock(Map<String, String> map) {
+		super(map);
+	}
+
+	protected Supplier<?> putSupplier(int x) {
+		return (()-> {
+			boolean done = false;
+			while(!done) {
+				map.put("key" + x, "value" + x);
+    			done = true;
+			}
+    		return null;
+		});
+	}
+	
+	protected Supplier<?> getSupplier(int x) {
+		return (()-> {
+			boolean done = false;
+			while(!done) {
+				map.get("key" + x);
+    			done = true;
+			}
+    		return null;
+		});
+	}
+}