java - 在 Spring Data MongoDB 中返回流时指定游标选项？

Question

我正在使用 Spring Data MongoDB(来自 Spring Boot 1.5.2.RELEASE 的 spring-boot-starter-data-mongodb)和 MongoDB 3.4.9 并且有定义了一个如下所示的存储库:

interface MyMongoDBRepository extends CrudRepository<MyDTO, String> {
    Stream<MyDTO> findAllByCategory(String category);
}

然后我有一个服务 MyService 与这个存储库交互:

@Service
class MyService {
    @Autowired
    MyMongoDBRepository repo;

    public void doStuff() {
        repo.findAllByCategory("category")
            .map(..)
            .filter(..)
            .forEach(..)
    }
}

数据库中的数据比较多，有时会出现这个错误:

2018-01-01 18:16:56.631 ERROR 1 --- [ask-scheduler-6] o.s.integration.handler.LoggingHandler : org.springframework.dao.DataAccessResourceFailureException: 
Query failed with error code -5 and error message 'Cursor 73973161000 not found on server <mongodb-server>' on server <mongodb-server>; 
nested exception is com.mongodb.MongoCursorNotFoundException: 
Query failed with error code -5 and error message 'Cursor 73973161000 not found on server <mongodb-server>' on server <mongodb-server> 
at org.springframework.data.mongodb.core.MongoExceptionTranslator.translateExceptionIfPossible(MongoExceptionTranslator.java:77) 
at org.springframework.data.mongodb.core.MongoTemplate.potentiallyConvertRuntimeException(MongoTemplate.java:2135) 
at org.springframework.data.mongodb.core.MongoTemplate.access$1100(MongoTemplate.java:147) 
at org.springframework.data.mongodb.core.MongoTemplate$CloseableIterableCursorAdapter.hasNext(MongoTemplate.java:2506)
at java.util.Iterator.forEachRemaining(Iterator.java:115) 
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) 
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) 
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151) 
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174) 
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) 
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418) 
at com.mycompany.MyService.doStuff(MyService.java:108) 
at com.mycompany.AnotherService.doStuff(AnotherService.java:42) 
at sun.reflect.GeneratedMethodAccessor2026.invoke(Unknown Source) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:498) 
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65) 
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) 
at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:81) 
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180) 
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) 
at java.lang.Thread.run(Thread.java:748) Caused by: com.mongodb.MongoCursorNotFoundException: Query failed with error code -5 and error message 'Cursor 73973161000 not found on server <mongodb-server>' on server <mongodb-server> 
at com.mongodb.operation.QueryHelper.translateCommandException(QueryHelper.java:27) 
at com.mongodb.operation.QueryBatchCursor.getMore(QueryBatchCursor.java:213) 
at com.mongodb.operation.QueryBatchCursor.hasNext(QueryBatchCursor.java:103) 
at com.mongodb.MongoBatchCursorAdapter.hasNext(MongoBatchCursorAdapter.java:46) 
at com.mongodb.DBCursor.hasNext(DBCursor.java:145) 
at org.springframework.data.mongodb.core.MongoTemplate$CloseableIterableCursorAdapter.hasNext(MongoTemplate.java:2504) ... 24 more

我在不同的地方读到过，当使用 vanilla MongoDB Java 客户端时，您可以将 MongoDB 游标配置为没有超时或设置批处理大小以有望缓解这种情况。

如果这是要走的路，那么当从 Spring Data MongoDB 返回 Stream 时我如何提供游标选项？

Answer 1

您的错误发生是因为您处理流的速度太慢，因此光标在您到达下一批之前超时。

批量大小可以在 Spring Data Query object 上设置，或使用 @Meta 在存储库上注解。例如:

Query query = query(where("firstname").is("luke"))
    .batchSize(100);

或者在使用存储库时:

@Meta(batchSize = 100)
List<Person> findByFirstname(String firstname);

参见 Spring Data MongoDB documentation了解更多详情。

也可以使用相同的配置在每个查询的基础上禁用游标超时。例如@Meta(flags = {CursorOption.NO_TIMEOUT})。

不能在每个查询的基础上更改游标超时。那是服务器配置。您需要使用 cursorTimeoutMillis服务器参数以在整个服务器范围内更改该服务器。