MapUpdater.java

package aaa;

import java.util.HashMap;

/**
 * Use -Xmx30G -Xms30G for 100,000,000 rows
 */
public class MapUpdater {

    public static void main(String[] args) throws InterruptedException {
        if (args.length != 2) {
            throw new RuntimeException("Usage: MapUpdater <map_size_mil> <update_count_mil>");
        }
        int mapSize = Integer.parseInt(args[0]) * 1000000;
        int updCnt = Integer.parseInt(args[1]) * 1000000;

        HashMap<String, Row> map = new HashMap<>((int) (mapSize * 1.1));
        for (int i = 0; i < mapSize; i++) {
            String dom = getDomain(i);
            map.put(dom, new Row());
        }
        System.out.println("Map Init Done");
        update(map, updCnt);
        update(map, updCnt);
        update(map, updCnt);
        update(map, updCnt);
    }

    static void update(HashMap<String, Row> map, int updCnt) throws InterruptedException {
        long s1 = System.currentTimeMillis();
        for (int i = 0; i < updCnt; i++) {
            String dom = getDomain(i);
            Row row = map.get(dom);
            row.v1 += 1L;
        }
        long s2 = System.currentTimeMillis();
        System.out.println(s2 - s1);
    }

    static class Row {
        public long v1;

        @Override
        public String toString() {
            return "row.v1: " + v1;
        }
    }

    static String getDomain(int i) {
        if (i < 10) {
            return "d00000000" + i;
        } else if (i < 100) {
            return "d0000000" + i;
        } else if (i < 1000) {
            return "d000000" + i;
        } else if (i < 10000) {
            return "d00000" + i;
        } else if (i < 100000) {
            return "d0000" + i;
        } else if (i < 1000000) {
            return "d000" + i;
        } else if (i < 10000000) {
            return "d00" + i;
        } else if (i < 100000000) {
            return "d0" + i;
        } else {
            return "d" + i;
        }
    }
}
//    Map Init Done
//        128
//        107
//        87
//        99