技術標籤：java技術

jdk8有一個非同步類CompletableFuture可以使用執行緒池幫助我們實現多執行緒查詢

@PostConstruct
    private void multithreadingGetData() {
	    // 資料總量
        int count = 312;
        // 計算機可用cpu 設定執行緒池個數最好與之匹配
        int availableProcessors = Runtime.getRuntime().availableProcessors();
        // 每個執行緒要查多少條
        int num =
 
 count / availableProcessors;

        ExecutorService executorService = Executors.newFixedThreadPool(availableProcessors);
        List<CompletableFuture> futures = new ArrayList<>();

        long start = System.currentTimeMillis();
        for (int i = 0; i < num; i++) {
            int id =
 
 (i + 1) * num;
            if(id <= count){
                //futures.add(CompletableFuture.supplyAsync(() -> officeResponsibilityMapper.multithreadingGetData(id), executorService));
                CompletableFuture.supplyAsync(() -> officeResponsibilityMapper.multithreadingGetData(id), executorService)
 
;
            }
        }
        executorService.shutdown();
        System.out.println("多執行緒查詢共用時間" + (System.currentTimeMillis() - start));

        long start2 = System.currentTimeMillis();
        officeResponsibilityMapper.selectAll();
        System.out.println("單執行緒查詢共用時間" + (System.currentTimeMillis() - start2));

        // List<Object> collect = futures.stream().map(CompletableFuture::join).collect(Collectors.toList());

    }

public interface OfficeResponsibilityMapper extends Mapper<OfficeResponsibilityEntity> {

    @Select("select * from office_responsibility where id <= #{id}" )
    List<OfficeResponsibilityEntity> multithreadingGetData(@Param("id") Integer id);
}

輸出如下

這還是僅有300條資料，資料多了之後使用多執行緒查效率高的可不是一點點