Java8でListをある程度まとめて並列処理 ref: http://qiita.com/thrakt/items/62d05c2ea0675f0f996f

file0.java

List<Map<String, Object>> rows = new ArrayList<>(); // データ入れる

rows.parallelStream().forEach(row -> {
    LOG.info("something to do.");
    LOG.info(row);
});

file1.java

List<Map<String, Object>> rows = new ArrayList<>(); // データ入れる

for (int start = 0; start < rows.size();) {
    int end = start + 100;
    if (end > oldRows.size()) {
        end = oldRows.size();
    }

    List<Map<String, Object>> subList = rows.subList(start, end);

    ForkJoinPool.commonPool().execute(() -> {
        LOG.info("something to doooooooooooooo.");
        subList.forEach(row -> {
            LOG.info(row);
        });
    });

    start = end;
}
});

// 終了待機
while (!ForkJoinPool.commonPool().awaitQuiescence(1, TimeUnit.HOURS));