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    <p>Why don't just use simple striped locking, like:</p> <pre><code>/** * Striped locks holder, contains array of {@link java.util.concurrent.locks.ReentrantLock}, on which lock/unlock * operations are performed. Purpose of this is to decrease lock contention. * &lt;p&gt;When client requests lock, it gives an integer argument, from which target lock is derived as follows: * index of lock in array equals to &lt;code&gt;id &amp; (locks.length - 1)&lt;/code&gt;. * Since &lt;code&gt;locks.length&lt;/code&gt; is the power of 2, &lt;code&gt;locks.length - 1&lt;/code&gt; is string of '1' bits, * and this means that all lower bits of argument are taken into account. * &lt;p&gt;Number of locks it can hold is bounded: it can be from set {2, 4, 8, 16, 32, 64}. */ public class StripedLock { private final ReentrantLock[] locks; /** * Default ctor, creates 16 locks */ public StripedLock() { this(4); } /** * Creates array of locks, size of array may be any from set {2, 4, 8, 16, 32, 64} * @param storagePower size of array will be equal to &lt;code&gt;Math.pow(2, storagePower)&lt;/code&gt; */ public StripedLock(int storagePower) { if (!(storagePower &gt;= 1 &amp;&amp; storagePower &lt;= 6)) { throw new IllegalArgumentException("storage power must be in [1..6]"); } int lockSize = (int) Math.pow(2, storagePower); locks = new ReentrantLock[lockSize]; for (int i = 0; i &lt; locks.length; i++) locks[i] = new ReentrantLock(); } /** * Locks lock associated with given id. * @param id value, from which lock is derived */ public void lock(int id) { getLock(id).lock(); } /** * Unlocks lock associated with given id. * @param id value, from which lock is derived */ public void unlock(int id) { getLock(id).unlock(); } /** * Map function between integer and lock from locks array * @param id argument * @return lock which is result of function */ private ReentrantLock getLock(int id) { return locks[id &amp; (locks.length - 1)]; } } </code></pre>
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    1. PODesigning a key based lock (or lock map)
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    1. USVictor Sorokin
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    1. COGuava library has an implementation of the Striped Lock. Take a look. http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/util/concurrent/Striped.html
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