traffic-shm (Shared Memory) is a Java based message library, which is designed for interprocess communication (IPC) on the same server.

Shared memory is an efficient mechanism for interprocess communication. Memory mapped files offer a dynamical memory management feature that allows applications to access files on disk in the same way they attach the shared segment of physical memory to their virtual address spaces.

traffic-shm provides a pure java implementation using sun.misc.Unsafe and FileChannel, JDK 1.6 is required.

alignment: 4-bytes aligned byteorder: big-endian

Most of the major operating systems like Linux, macOS, Windows, AIX and HP-UX are supported.

Note:

• set -Xmpas:on on HP-UX
• set --add-opens=java.base/jdk.internal.misc=ALL-UNNAMED option to support JDK 9

With non-blocking algorithm, implementation of multi-producer/single-consumer and multi-producer/multi-consumer concurrent queue, traffic-shm could be use to build a real-time system with high throughput and low latency.

traffic-shm provides a FIFO queue which is ONCE-AND-ONLY-ONCE guaranteed. cursor is forward only, once a message is delivered successfully, message is AUTOMATIC ACKNOWLEDGEMENT which means that a message is acknowledged as soon as the receiver gets it.

offer a multi-producer/single-consumer concurrent data structure

Async Mode:

Async:

Reader:

Queue queue = Queue.map("/Users/peptos/ashm", 2000L);;

while (running) {
	Block block = queue.poll();
	if (block != null) {
		System.out.println(new String(block.getPayload(), "UTF-8"));
	} else {
		Util.pause(10);
	}
}

queue.close();

Writer:

Queue queue = Queue.attach("/Users/peptos/ashm");

String string = "hello, world";
byte[] bytes = string.getBytes("UTF-8");
System.out.println(queue.offer(new Block(bytes)));

queue.close();