SharedHashMap是更低延迟无GC暂停的Map实现

SharedHashMapBuilder builder = new SharedHashMapBuilder();
	String shmPath = System.getProperty("java.io.tmpdir") + System.getProperty("file.separator") + "SHMTest1";
	//Declare as a ConcurrentMap rather than Map if you want to use putIfAbsent()
	Map<String, SHMTest1Data> theSharedMap = builder.create(new File(shmPath), String.class, SHMTest1Data.class)
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public static class SHMTest1Data implements Serializable {
		private long[] time;
		public SHMTest1Data(int maxNumberOfProcessesAllowed) {
			this.time = new long[maxNumberOfProcessesAllowed];
		}
		public int getMaxNumberOfProcessesAllowed() {
			return this.time.length;
		}
		public void setTimeAt(int index, long time) {
			this.time[index] = time;
		}
		public long getTimeAt(int index) {
			return this.time[index];
		}
	}
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SHMTest1Data data = theSharedMap.get("whatever");
	if (data == null) {
		//From 1.8, we could use putIfAbsent() as that's been added to the Map interface.
		//Alternatively we can cast to SharedHashMap and use putIfAbsent().
		//But for this test just bang it in, doesn't matter if something
		//else gets in first as you'll see below
		data = new SHMTest1Data(2);
		theSharedMap.put("whatever", data);
	}
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