并发编程回望：synchronized与Lock

并发编程回顾：synchronized与Lock

上面程序中，让read方法持有锁1s，且只进行读操作打印data值，write方法持有锁的时间稍短一些0.1s，同时进行写操作给data赋值。

进行读写操作：

此处启动3个线程，一个循环写入data随机数，另外2个线程循环读取data值。

class RWDictionary {    private final Map<String, Data> m = new TreeMap<String, Data>();    private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();    private final Lock r = rwl.readLock();    private final Lock w = rwl.writeLock();    public Data get(String key) {        r.lock();        try { return m.get(key); }        finally { r.unlock(); }    }    public String[] allKeys() {        r.lock();        try { return m.keySet().toArray(); }        finally { r.unlock(); }    }    public Data put(String key, Data value) {        w.lock();        try { return m.put(key, value); }        finally { w.unlock(); }    }    public void clear() {        w.lock();        try { m.clear(); }        finally { w.unlock(); }    }}

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