driver-legacy/src/main/com/mongodb/DBCollection.java
@Deprecated
    public List<Cursor> parallelScan(final ParallelScanOptions options) {
        List<Cursor> cursors = new ArrayList<Cursor>();
        ParallelCollectionScanOperation<DBObject> operation = new ParallelCollectionScanOperation<DBObject>(getNamespace(),
                                                                                                            options.getNumCursors(),
                                                                                                            objectCodec)
                                                                  .batchSize(options.getBatchSize()).retryReads(retryReads);
        ReadPreference readPreferenceFromOptions = options.getReadPreference();
        List<BatchCursor<DBObject>> mongoCursors = executor.execute(operation,
                                                                    readPreferenceFromOptions != null ? readPreferenceFromOptions
                                                                                                        : getReadPreference(),
                getReadConcern());

        for (BatchCursor<DBObject> mongoCursor : mongoCursors) {
            cursors.add(new MongoCursorAdapter(new MongoBatchCursorAdapter<DBObject>(mongoCursor)));
        }
        return cursors;
    }
@Deprecated
    public List<Cursor> parallelScan(final ParallelScanOptions options) {
        List<Cursor> cursors = new ArrayList<Cursor>();
        ParallelCollectionScanOperation<DBObject> operation = new ParallelCollectionScanOperation<DBObject>(getNamespace(),
                                                                                                            options.getNumCursors(),
                                                                                                            objectCodec)
                                                                  .batchSize(options.getBatchSize()).retryReads(retryReads);
        ReadPreference readPreferenceFromOptions = options.getReadPreference();
        List<BatchCursor<DBObject>> mongoCursors = executor.execute(operation,
                                                                    readPreferenceFromOptions != null ? readPreferenceFromOptions
                                                                                                        : getReadPreference(),
                getReadConcern());

        for (BatchCursor<DBObject> mongoCursor : mongoCursors) {
            cursors.add(new MongoCursorAdapter(new MongoBatchCursorAdapter<DBObject>(mongoCursor)));
        }
        return cursors;
    }
@ Deprecated public List < Cursor > parallelScan ( final ParallelScanOptions options ) { List < Cursor > cursors = new ArrayList < Cursor > ( ) ; ParallelCollectionScanOperation < DBObject > operation = new ParallelCollectionScanOperation < DBObject > ( getNamespace ( ) , options . getNumCursors ( ) , objectCodec ) . batchSize ( options . getBatchSize ( ) ) . retryReads ( retryReads ) ; ReadPreference readPreferenceFromOptions = options . getReadPreference ( ) ; List < BatchCursor < DBObject > > mongoCursors = executor . execute ( operation , readPreferenceFromOptions != null ? readPreferenceFromOptions : getReadPreference ( ) , getReadConcern ( ) ) ; for ( BatchCursor < DBObject > mongoCursor : mongoCursors ) { cursors . add ( new MongoCursorAdapter ( new MongoBatchCursorAdapter < DBObject > ( mongoCursor ) ) ) ; } return cursors ; }
<p>Return a list of cursors over the collection that can be used to scan it in parallel.</p>

<p>Note: As of MongoDB 2.6, this method will work against a mongod, but not a mongos. </p>

@param options the parallel scan options
@return a list of cursors, whose size may be less than the number requested
@mongodb.driver.manual reference/command/parallelCollectionScan/ Parallel Collection Scan
@mongodb.server.release 2.6
@since 2.12
@deprecated the parallelCollectionScan command will be removed in MongoDB 4.2
<p > Return a list of cursors over the collection that can be used to scan it in parallel . < / p >