LongTTSP.java

import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;
import java.nio.file.Paths;
import java.time.LocalDateTime;

public class LongTTSP {
    public static void main(String[] args) throws Exception {
        log(String.format("pid: %d", ProcessHandle.current().pid()));

        Thread th = new Thread(() -> {
            log("Gonna read from mapped file");
            long t0 = System.nanoTime();
            new MappedFile(args[0]).read();
            log(String.format("Finished read in %d us", (System.nanoTime() - t0) / 1000));
        });
        th.setName("reader-thread");
        th.start();
        log("Sleeping...");
        Thread.sleep(10000L);
    }

    static class MappedFile {
        private final MappedByteBuffer buffer;

        MappedFile(String path) {
            try (FileChannel channel = FileChannel.open(Paths.get(path))) {
                buffer = channel.map(MapMode.READ_ONLY, 0, channel.size());
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }

        void read() {
            buffer.get(0);
        }
    }

    static void log(String msg) {
        System.out.printf("[%s] (%s) %s\n",
                          LocalDateTime.now(),
                          Thread.currentThread().getName(),
                          msg);
    }
}