JavaLockProfiler.java

import java.lang.management.LockInfo;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.util.HashMap;
import java.util.Map;

/**
 * http://stackoverflow.com/a/2362939
 */
public class JavaLockProfiler {

	public static void main(String[] args) throws Exception {
		Thread thr = new Thread() {
			public void run() {
				runProfile();
			}
		};
		thr.setPriority(Thread.MAX_PRIORITY - 1);
		thr.start();

		// TODO add code to profile here...
	}

	private static void runProfile() {
		try {
			final int noSeconds = 100;
			final int sleepMillis = 50;
			final int noSamples = noSeconds * 1000 / sleepMillis;

			ThreadMXBean thb = ManagementFactory.getThreadMXBean();
			Map<String, Integer> blockCounts = new HashMap<String, Integer>(50);
			for (int i = 0; i < noSamples; i++) {
				long[] ids = thb.getAllThreadIds();
				ThreadInfo[] infs = thb.getThreadInfo(ids, 0);
				for (ThreadInfo ti : infs) {
					LockInfo lockInf = ti.getLockInfo();
					if (lockInf != null) {
						String key = lockInf.toString();
						Integer cnt = blockCounts.get(key);
						blockCounts.put(key, cnt == null ? 1 : cnt + 1);
					}
				}

				Thread.sleep(sleepMillis);
			}

			System.out.println("Locks:");
			for (String lockName : blockCounts.keySet()) {
				System.out.println(lockName + " : " + blockCounts.get(lockName));
			}
		} catch (InterruptedException iex) {
			Thread.currentThread().interrupt();
		}
	}
}