Manual Backfill implementation always return Timeout

I am currently developing by following This workshop (Persistent GameLift HoL :: Persistent Game Server on GameLift).

I am trying to implement “Manual Backfill” using StartMatchBackfill API and StopMatchBackfill API.
And I am going to call StartMatchBackfill API on a lambda function as follows. I used Lambda Python SDK to call StartMatchmaking API.

Currently my workflow is :

  1. Client A calls StartMatchmaking API and join the game A. (min Player : 0)
            match_response = gamelift.start_matchmaking(
                 Players = [ { 'PlayerId' : "ClientA", 'PlayerAttributes' : {'world': {'S': worldId }, 'level': {'N': 1}} } ]
  1. Client B calls StartMatchBackfill API to join the game A. It seems like :
            match_response = gamelift.start_match_backfill(
                    Players = [
                                'PlayerId': "ClientB",
                                'PlayerAttributes': {'world': {'S': worldId }, 'level': {'N': 1}}
  1. Responses are always Matchmaking Timedout.

Is it bug on GameLift? I searched the several topics in this forum, but I could not find Manual Backfill implementation guidelines.

If not, could you please help me to correct my code & request?

Hi @PThomas

  1. Have you by any chance tried to call start_matchmaking normally for ClientB and get matches consistently? If not, check and make sure your fleet(s) have at least 1 ACTIVE instance and 1 available process.
  2. Does your ruleset match step 10 of Configuring FlexMatch Environment :: Persistent Game Server on GameLift or have you by any chance modified the ruleset?
  3. (Unless you are already doing so) Alternatively, you can also test matchmaker in an isolated fashion, i.e. no queues/fleets to introduce extra points of failure. See Standalone flexmatch: GameLift FlexMatch integration for standalone matchmaking - Amazon GameLift

Hi, James.

  1. Is it correct status? ClientA could play the game well. But ClientB can not join the existing game session. Although there is a game session, it describes 0 in Fleet overview.

  1. I have not changed yet.

  2. Not yet. I will also check Standalone Matchmaking.

It seems like there is no active game session in GameLift overview, even though there is active game session. Is it bug in console? Or did I set something wrong?

That could potentially be a known issue on the GameLift console, the values you underlined is aggregated across all of your locations, and the update could be delayed for up to 10 seconds. If you refresh the page you might be able to see it being updated. If not, please let us know and we’ll take a look.

But ClientB can not join the existing game session

Do you mean you tried to match A and B together without using backfill, and ClientB still cannot join? I.e.

  Players = [ { 'PlayerId' : "ClientA", 'PlayerAttributes' : {'world': {'S': worldId }, 'level': {'N': 1}} } ]
  Players = [ { 'PlayerId' : "ClientB", 'PlayerAttributes' : {'world': {'S': worldId }, 'level': {'N': 1}} } ]

If that’s the case, could you call DescribeGameSessions with the game session ID after ClientA is matched, and see if “PlayerSessionCreationPolicy” is somehow updated to DENY_ALL? (It should be ACCEPT_ALL) DescribeGameSessions - GameLift Service

I will also check Standalone Matchmaking.

Thanks, please let us know if this helps. If it’s still not the case, I can get the GameLift team to take a look for you in our backend.

I am trying to match A and B together “using” Manual Backfill. Is this possible?

I tested DescribeGameSessions as you mentioned, but could not get “PlayerSessionCreationPolicy”.
So, it is not ACCEPT_ALL and DENY_ALL both.

Also I could check PlayerSessionCreationPolicy is Optional response through This document.

When could I get the element?

Hi @PThomas

I’m getting a GameLift engineer to look into this for you.



Hi @PThomas

Can you let us know the following information so that we can investigate?

  1. matchmaking configuration
  2. aws region
  3. backfill ticket id
  4. non-backfill ticket id that you expected to match with (3)
  5. Approximate time (with timezone) of when these tickets were submited?


Hi BrianS!

Here is the information.

Matchmaking Configuration Name : ’ Manual-Backfill-01’
AWS Region : ap-northeast-2
Ticket ID : 86af31a4-211a-48eb-9ad3-a547eea67bb0
I submitted the Manual Backfill Ticket 05:55 UTC