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java - 如何让主线程等待执行器服务线程完成

问题描述

这是我的主线程，在每个进程中我都在调用执行器服务线程。在第 4 行，在更新状态之前，我想等待我的所有线程完成

 line 1- missingStrategyContext.process(FileType.CARD, programId, fromDate, toDate, channel);
 line 2- missingStrategyContext.process(FileType.TRANSACTION, programId, fromDate, toDate, channel);
 line 3- missingStrategyContext.process(FileType.REFUND, programId, fromDate, toDate, channel);

 line 4- processingLog.setProcessingStatus(TransactionState.SUCCESS.name());

在每个进程中，我决定文件类型值我必须调用哪种策略

public void process(FileType fileType, String programId, Long fromDate, Long toDate, String channel){
    map.get(fileType).process(programId, fromDate, toDate, channel, fileType);
}

然后根据文件类型，我实现了我的处理方法并在每个文件类型实现中调用了执行器服务

@Override
public void process(String programId, Long fromDate, Long toDate, String channel, FileType fileType) {

    MultiTenantTxMgmt multiTenantTxMgmt = MultiTenantTxMgmtUtil.get(programId);
    EntityManager entityManager = null;

    List<MissingReason> reasonList = new ArrayList<>();
    try {
        entityManager = multiTenantTxMgmt.getEntityManager();
        reasonList = missingDataRepository.getDistinctMissingReasonForFileType(entityManager, fileType, TransactionState.READYTOATTEMPT);
    }catch (Exception exception) {
        logger.error(exception.getMessage(), exception);
        throw new UnkownBatchSaveException();
    } finally {
        entityManager.close();
    }

    reasonList.forEach(
            missingReason -> deExecutorService.dotask(() ->
                    missingTransactionStrategyContext.processMissingV3(missingReason, programId, fromDate, toDate, channel, fileType)
            )
    );

}

标签： javamultithreadingexecutorservice

解决方案

您可以使用CountDownLatch#await. 例如从文档复制：

CountDownLatch startSignal = new CountDownLatch(1);
CountDownLatch doneSignal = new CountDownLatch(N);

for (int i = 0; i < N; ++i) // create and start threads
    new Thread(new Worker(startSignal, doneSignal)).start();

doSomethingElse();            // don't let run yet
startSignal.countDown();      // let all threads proceed
doSomethingElse();
doneSignal.await();           // wait for all to finish

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