What would cause "Request timed out" in parse.com cloud code count?

Question

One of my cloud functions is timing out occasionally. It seems to have trouble with counting, although there are only around 700 objects in the class. I would appreciate any tips on how to debug this issue.

The cloud function works correctly most of the time.

Example error logged:

E2015-02-03T02:21:41.410Z] v199: Ran cloud function GetPlayerWorldLevelRank for user xl8YjQElLO with:
  Input: {"levelID":60}
  Failed with: PlayerWorldLevelRank first count error: Request timed out

Is there anything that looks odd in the code below? The time out error is usually thrown in the second count (query3), although sometimes it times out in the first count (query2).

Parse.Cloud.define("GetPlayerWorldLevelRank", function(request, response) {    
    var query = new Parse.Query("LevelRecords");
    query.equalTo("owner", request.user);
    query.equalTo("levelID", request.params.levelID);
    query.first().then(function(levelRecord) {
        if (levelRecord === undefined) {
            response.success(null);
        }
        // if player has a record, work out his ranking
        else {
            var query2 = new Parse.Query("LevelRecords");
            query2.equalTo("levelID", request.params.levelID);
            query2.lessThan("timeSeconds", levelRecord.get("timeSeconds"));
            query2.count({
                success: function(countOne) {
                    var numPlayersRankedHigher = countOne;

                    var query3 = new Parse.Query("LevelRecords");
                    query3.equalTo("levelID", request.params.levelID);
                    query3.equalTo("timeSeconds", levelRecord.get("timeSeconds"));
                    query3.lessThan("bestTimeUpdatedAt", levelRecord.get("bestTimeUpdatedAt"));
                    query3.count({
                        success: function(countTwo) {
                            numPlayersRankedHigher += countTwo;
                            var playerRanking = numPlayersRankedHigher + 1;                    
                            levelRecord.set("rank", playerRanking);
                            // The SDK doesn't allow an object that has been changed to be serialized into a response.
                            // This would disable the check and allow you to return the modified object.
                            levelRecord.dirty = function() { return false; };    
                            response.success(levelRecord);    
                        },
                        error: function(error) {
                            response.error("PlayerWorldLevelRank second count error: " + error.message);
                        }                            
                    });
                },
                error: function(error) {
                    response.error("PlayerWorldLevelRank first count error: " + error.message);
                }
            });
         }
    });
});

Answer 1

I don't think the issue is in your code. Like the error message states: the request times out. That is, the Parse API doesn't respond within the period of the timeout or the network causes it to timeout. As soon as you do .count some API call is probably done, which then can't connect or times out.

Apparently more people have this issue: https://www.parse.com/questions/ios-test-connectivity-to-parse-and-timeout-question. It doesn't seem possible to increase the timeout, so the suggestion in this post states:

For that reason, I suggest setting a NSTimer prior to executing the query, and invalidating it when the query returns. If the NSTimer fires before being invalidated, ask the user if they want to keep waiting for the results to come back, or show them a message indicating that the request is taking a long time to complete. This gives the user the chance to wait more if they know their current network conditions are not ideal.

In case you are dealing with networks, and especially on the mobile platform, you need to prepare for network hickups. So like the post suggests: offer the option to user to try again.