mongoDB：游标notimeout设置在java客户端中不起作用

Question

i set an 'notimeout' option to a dbcursor in java:

    BasicDBObject nearbyQueries = new BasicDBObject("$gt", 0)
            .append("$lte", 2);
    DBCursor trueClassInstances = locationsCollection.find(new BasicDBObject("distanceFromHotel", nearbyQueries)).addOption(Bytes.QUERYOPTION_NOTIMEOUT).limit(100000);
    double counter = 0;
    int currentPresent = 0;
    for (DBObject instance : trueClassInstances) {

        ...
    }

even with this option i set, this exception is thrown:

Exception in thread "main" com.mongodb.MongoCursorNotFoundException: Query failed with error code -5 and error message 'Cursor 1876954464377 not found on server XXXXXX:27017' on server XXXXXXXX:27017
    at com.mongodb.connection.GetMoreProtocol.receiveMessage(GetMoreProtocol.java:115)
    at com.mongodb.connection.GetMoreProtocol.execute(GetMoreProtocol.java:68)
    at com.mongodb.connection.GetMoreProtocol.execute(GetMoreProtocol.java:37)
    at com.mongodb.connection.DefaultServer$DefaultServerProtocolExecutor.execute(DefaultServer.java:155)
    at com.mongodb.connection.DefaultServerConnection.executeProtocol(DefaultServerConnection.java:219)
    at com.mongodb.connection.DefaultServerConnection.getMore(DefaultServerConnection.java:194)
    at com.mongodb.operation.QueryBatchCursor.getMore(QueryBatchCursor.java:197)
    at com.mongodb.operation.QueryBatchCursor.hasNext(QueryBatchCursor.java:93)
    at com.mongodb.MongoBatchCursorAdapter.hasNext(MongoBatchCursorAdapter.java:46)
    at com.mongodb.DBCursor.hasNext(DBCursor.java:152)
    at locationExtraction.DistanceClassification.FeatureAnalyzer.main(FeatureAnalyzer.java:27)

FeatureAnalyzer.java:27 is the for loop line.

this problem appear in other project with similar setting...

what am i doing wrong? maybe my choice of 'for' loop instead of this kind of iteration can cause this strange behavior?

while(cursor.hasNext())
{
      DBObject next = cursor.next();
}

Thanks

Answer 1

Looks like you are not able to process each batch within time limit. Try reducing batch size so that each batch could be consumed before time runs out. This should help. cursor.addOption(com.mongodb.Bytes.QUERYOPTION_NOTIMEOUT).batchSize(100)

Answer 2

so the problem is solved. this is very strange but there is a problem with using 'for' loop for iterating on cursor. so dont do it like i did it, use 'while' loop:

while(cursor.hasNext())
{
      DBObject next = cursor.next();
}

Answer 3

before use cursor.hasNext() and cursor.next() to do business logical, just before you get the mongo cursor, invoke FindIterable object's noCursorTimeout(true) method. for example:

FindIterable<Document> findIterable = sentenceColl.find(condition);
// set no timeout
findIterable.noCursorTimeout(true);
MongoCursor<Document> mongoCursor = findIterable.iterator();

while (mongoCursor.hasNext()) {
    mongoCursor.next();
}

Answer 4

try this:

Iterator<BasicDBObject> it = null;
it = coll.find("{"field": {$in:#}}", fieldList).with(
        new QueryModifier() {
          public void modify(DBCursor cursor) {
              cursor.setOptions(Bytes.QUERYOPTION_NOTIMEOUT);
          }
        }
    ).as(BasicDBObject.class);