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Question

我正在尝试运行一个需要在我的数据库的每个文档上循环的脚本（使用NoSQL数据库）并复制每个文档“x time”。我知道因为数据库可能有很多文档，并且因为我们可以按照希望的时间复制它们，所以可以发生OOM。我试图避免它，但它仍然发生。有人可以帮我吗？这是我的代码：

private void duplicates(int xFirsts, Integer nbOccurrences, DatabaseDuplicator duplicator) {
    if(duplicateAllPatient.get())
        totalPatientsToDuplicate = couchbase.patientManager().count(false, false, null);
    else
        totalPatientsToDuplicate = xFirsts;

    //Limit is to avoid to get an OOM error by getting too much patients from the database.
    int limit = 500;
    int skip = 0;

    List<Patient> patients = couchbase.patientManager().findAll(limit, skip);

    while (patients != null && !patients.isEmpty() && nbPatientsDuplicated < totalPatientsToDuplicate) {
        startDuplication(nbOccurrences, duplicator, patients);
        skip += limit;
        if((skip + limit) > totalPatientsToDuplicate)
            limit = totalPatientsToDuplicate - skip;
        patients = couchbase.patientManager().findAll(limit, skip);
    }
}

private void startDuplication(final Integer nbOccurrences, final DatabaseDuplicator duplicator, final List<Patient> patients) {
    loadingInformation.set("");
    Observable<Integer> observable = Observable.create(new Observable.OnSubscribe<Integer>() {
        @Override
        public void call(Subscriber<? super Integer> subscriber){
            for (int i = 0; i < nbOccurrences; i++){
                duplicator.duplicatePatientsWithTheirMedicalRecords(patients, ToolsActivityViewModel.this);
                subscriber.onNext(i);
            }
        }
    });
    observable.subscribeOn(Schedulers.newThread())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(new Observer<Integer>() {
                @Override
                public void onCompleted() {

                }

                @Override
                public void onError(Throwable e) {
                    e.printStackTrace();
                }

                @Override
                public void onNext(Integer integer) {
                    informUserOnDuplicationProgress();
                }
            });
}

Answer 1

两件事：你的observable永远不会完成，你一次启动很多（订阅发生在不同的线程上）。

使用此：

    Observable
    .range(0, nbOccurrences)
    .doOnNext(i -> duplicator.duplicatePatientsWithTheirMedicalRecords(patients, ToolsActivityViewModel.this))
    .doOnNext(i -> informUserOnDuplicationProgress())
    .subscribeOn(Schedulers.newThread())
    .observeOn(AndroidSchedulers.mainThread())
    .toBlocking()
    .lastOrDefault(null);