Reliable message lost???

ufnvufnv
edited May 28 in Native
Strange behaviour observed with the messages that exceed UDP package size. Sometimes they just get lost.

The code looks like this:
Result =  mLoadBalancingClient.opRaiseEvent(true
                                                  , data
                                                  , size
                                                  , Code
                                                  , ExitGames::LoadBalancing::RaiseEventOptions().setReceiverGroup(Lite::ReceiverGroup::OTHERS)
                                                  );

immediately followed by
    mLoadBalancingClient.serviceBasic();
    mLoadBalancingClient.sendOutgoingCommands())

To check the delivery I attach the message ID to each message and print it to trace dump.

On the receiving side I also print the ID of the received message.

Under the heavy load (several messages that exceed UDP package size in row), a couple of messages get lost.

What could be the reason and how I could debug this further?

Comments

  • ufnvufnv
    To add on this - no warning or errors received from Photon.
  • ufnvufnv
    Update - sometimes I get this warning:

    PHOTON: WARNING code: 1037 (PhotonPeer sent queue is filling up. Check, why the server does not acknowledge your sent reliable commands.)
  • ufnvufnv
    When I send a lot of less than udp size packages, they also get lost.

    Also heavily depends on the regional server that I am connecting to - some are better, some are worse, but sending something like 60-100 packages per second, each of 1024 bytes or so eventually leads to the packets not arriving to clients. But the connection is kept, no player gets the "disconnect" callback.

    Sometimes arrives WARNING enetpeer.cpp ExitGames::Photon::Internal::EnetPeer::queueSentReliableCommand() 959 WARNING! There are 100 sent reliable messages waiting for their acknowledgement!

    followed by PHOTON: WARNING code: 1037, but not necessarily. Quite often the messages are just being lost without any warning.

    No warnings or errors at the client (receiving) side.
  • Hi @ufnv.

    I can't reproduce the missing messages. Either the messages arrive or my client gets disconnected.
    Could you provide us with a minimal self-contained reproduction project, please?

  • ufnvufnv
    I will try. It is 100% reproducible for me. Maybe I'll just record the packets and the timing to be able to reproduce it.
  • ufnvufnv
    edited June 1
    @Kaiserludi

    Uploaded the code here:

    https://drive.google.com/file/d/1usIQ25APvW_dM1FPHwIUTiWw57OJVvD1/view?usp=sharing

    It's a VS 2017 project that builds the "player" of the recorded traffic.
    The record itself is PhotonLostMessages/server_dump.bin file.
    This file needs to be in the same directory as the "server" executable (for example, x64/Release/).

    You need to start the PhotonLostMessages.exe, then when it prints "Waiting for Player 0 to join...", start the client.exe.

    The server application then will be sending the recorded packages in the same order and with (approximately) the same timing as it was recorded inside the game.

    The client application will be reading the received packages and count the markers received. When some package is lost, it will notify with the "MESSAGE LOST!!!" note.

    Both applications also print the Photon output.

    I've recorded a very stressful trace just to be sure the lost package will appear, so finally the forced disconnect will arrive, but much too late - already a lot of packages will be lost and in the real game this can easily lead to crashes, as the game does not expect any package to be lost. It expects them either to be delivered in order or to get forced disconnect in the worse case scenario.

    This example is a little extreme - throwing 50 messages per second, 5-10K each for about 3-5 seconds - it is considered a too heavy load already?
  • TobiasTobias admin
    edited June 2
    Yes, this amount of load is too much.
    You want to avoid sending chunks > MTU (1200 bytes which also must contain the headers / type info). Else, the message becomes fragmented and sent reliable.
    If any of the messages fail to send entirely, that will lead to a timeout.

    Please share the Wireshark capture. We would like to look at that before running any exe.
  • ufnvufnv
    What is Wireshark capture?

    The problem is with this kind of load the reliable packets start disappearing long before the timeout. Or there can be no time-out at all if the load is more moderate. Here I've used the extra load just to make sure the problem is 100% reproducible.

    Still for the real game there can be situation when the reliably sent packet is lost and there is no timeout nor any warning/error.
  • ufnvufnv
    edited June 2
    The trace output looks like this:

    Note the first lost message is nearly two hundred messages before the disconnect finally happened.
    If to stop the extra load right after the first lost message, the disconnect will never happen.

    Also, no need to run the provided exe's, just compile and run the provided code - it's the safest way.
    Connecting...done
    Joining Room...done
      received message 1
      received message 2
      received message 3
      received message 4
      received message 5
      received message 6
      received message 7
      received message 8
      received message 9
      received message 10
      received message 11
      received message 12
      received message 13
      received message 14
      received message 15
      received message 16
      received message 17
      received message 18
      received message 19
      received message 20
      received message 21
      received message 22
      received message 23
      received message 24
      received message 25
      received message 26
      received message 27
      received message 28
      received message 29
      received message 30
      received message 31
      received message 32
      received message 33
      received message 34
      received message 35
      received message 36
      received message 37
      received message 38
      received message 39
      received message 40
      received message 41
      received message 42
      received message 43
      received message 44
      received message 45
      received message 46
      received message 47
      received message 48
      received message 49
      received message 50
      received message 51
      received message 52
      received message 53
      received message 54
      received message 55
      received message 56
      received message 57
      received message 58
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      received message 60
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      received message 280
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      received message 282
      received message 283
      received message 284
      received message 285
      received message 287
    MESSAGE LOST 286!!!
      received message 288
      received message 289
      received message 290
      received message 291
      received message 292
      received message 304
    MESSAGE LOST 293!!!
    MESSAGE LOST 294!!!
    MESSAGE LOST 295!!!
    MESSAGE LOST 296!!!
    MESSAGE LOST 297!!!
    MESSAGE LOST 298!!!
    MESSAGE LOST 299!!!
    MESSAGE LOST 300!!!
    MESSAGE LOST 301!!!
    MESSAGE LOST 302!!!
    MESSAGE LOST 303!!!
      received message 305
      received message 306
      received message 307
      received message 308
      received message 318
    MESSAGE LOST 309!!!
    MESSAGE LOST 310!!!
    MESSAGE LOST 311!!!
    MESSAGE LOST 312!!!
    MESSAGE LOST 313!!!
    MESSAGE LOST 314!!!
    MESSAGE LOST 315!!!
    MESSAGE LOST 316!!!
    MESSAGE LOST 317!!!
      received message 319
      received message 320
      received message 321
      received message 322
      received message 323
      received message 332
    MESSAGE LOST 324!!!
    MESSAGE LOST 325!!!
    MESSAGE LOST 326!!!
    MESSAGE LOST 327!!!
    MESSAGE LOST 328!!!
    MESSAGE LOST 329!!!
    MESSAGE LOST 330!!!
    MESSAGE LOST 331!!!
      received message 333
      received message 334
      received message 335
      received message 336
      received message 337
      received message 344
    MESSAGE LOST 338!!!
    MESSAGE LOST 339!!!
    MESSAGE LOST 340!!!
    MESSAGE LOST 341!!!
    MESSAGE LOST 342!!!
    MESSAGE LOST 343!!!
      received message 345
      received message 346
      received message 347
      received message 348
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      received message 358
    MESSAGE LOST 350!!!
    MESSAGE LOST 351!!!
    MESSAGE LOST 352!!!
    MESSAGE LOST 353!!!
    MESSAGE LOST 354!!!
    MESSAGE LOST 355!!!
    MESSAGE LOST 356!!!
    MESSAGE LOST 357!!!
      received message 359
      received message 360
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      received message 371
    MESSAGE LOST 364!!!
    MESSAGE LOST 365!!!
    MESSAGE LOST 366!!!
    MESSAGE LOST 367!!!
    MESSAGE LOST 368!!!
    MESSAGE LOST 369!!!
    MESSAGE LOST 370!!!
      received message 372
      received message 373
      received message 374
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      received message 384
    MESSAGE LOST 376!!!
    MESSAGE LOST 377!!!
    MESSAGE LOST 378!!!
    MESSAGE LOST 379!!!
    MESSAGE LOST 380!!!
    MESSAGE LOST 381!!!
    MESSAGE LOST 382!!!
    MESSAGE LOST 383!!!
      received message 385
      received message 386
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      received message 389
    MESSAGE LOST 388!!!
      received message 391
    MESSAGE LOST 390!!!
      received message 396
    MESSAGE LOST 392!!!
    MESSAGE LOST 393!!!
    MESSAGE LOST 394!!!
    MESSAGE LOST 395!!!
      received message 397
      received message 398
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      received message 400
      received message 402
    MESSAGE LOST 401!!!
      received message 405
    MESSAGE LOST 403!!!
    MESSAGE LOST 404!!!
      received message 407
    MESSAGE LOST 406!!!
      received message 409
    MESSAGE LOST 408!!!
      received message 410
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      received message 435
    
  • Hi @ufnv.
    What is Wireshark capture?
    See
    https://doc.photonengine.com/en-us/realtime/current/troubleshooting/analyzing-disconnects/#wireshark
    and
    https://www.wireshark.org/#download

    I have had a look into your repro-project and I can reproduce the issue with it. However I have not yet found the time to debug why this is happening.

    I will continue looking into this next week.
  • TobiasTobias admin
    If you can provide the wireshark captures, I can have a look asap and analyze if there is anything odd with it.
    Ludi is our expert for everything "native", so he has to look into the lib itself.
  • ufnvufnv
    @Tobias Thanks!

    I believe the traffic itself is fine just big at peaks, it's something happening inside, when the traffic overloads the server.

    As far as I understand Ludi was able to reproduce the problem, so I hope the issue will be found soon.
  • TobiasTobias admin
    Yes, it's a good first step to repro!

    Ludi has a few days off but we'll continue when he's back early next week.

    As said: The capture can help analyze what happens. But if you don't have the time for this, we can do one next week, too.
  • Hi!

    Any news on the issue? @Kaiserludi ?
  • TobiasTobias admin
    edited June 11
    Ludi reproduced this.
    We see that the server disconnects the clients due to internal buffering limits. You exceed the limits quite frequently with your appid.
    This may look like loss but actually, it is just the precursor for a disconnect. This is correct behaviour, as either side becomes unable to push everything you enqueued.

    You need to reduce the amount of data you send.
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