BGE leaves references in memory after quitting #44557

New Issue

Sybren A. Stüvel · 2015-04-30T11:18:08+02:00

Sybren A. Stüvel commented

2015-04-30 11:18:08 +02:00

Description:

When the BGE quits, there are still remainders of game engine objects in memory. This can be seen when inspecting gc.get_objects(). These are probably dead proxies, which apparently can still hold references.

>>> import gc

 
### Before I run the game:
>>> o = [repr(o) for o in gc.get_objects()]

 
### fine, no error. Now I start the BGE, quit it, and do this again:
>>> o = [repr(o) for o in gc.get_objects()]

Traceback (most recent call last):
  File "/usr/lib/python3.4/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<blender_console>", line 1, in <module>
  File "<blender_console>", line 1, in <listcomp>

    SystemError: Blender Game Engine data has been freed, cannot use this python variable

Tested on: Blender 2.74 and latest version from Git (f8540d7fd5)
Running Kubuntu Linux 14.10 64-bit, compiled the version from Git with GCC 4.9.1-16ubuntu6

To reproduce:

Open bge-garbage-test.blend
Run the script and check the terminal for output. It should show a little header and then "Found nothing wrong."
Move the mouse into the 3D view and press P to start the GE.
Press ESC to stop the GE.

Run the script again, and check the terminal for output. On my machine it shows:

============================================================
Performing garbage check
============================================================
Found one: 7f0f6c3edc48 = Blender Game Engine data has been freed, cannot use this python variable
Referrers are:
    - 7f0f881044c8 = (dead proxy 'Blender Game Engine data has been freed, cannot use this python variable')
    - 7f0f6c3de408 = <module 'GameLogic'>
Referents are:
    - 7f0f6c176a08 = <built-in function getMaxLogicFrame>
    - 7f0f6cf19750 = (dead proxy 'Blender Game Engine data has been freed, cannot use this python variable')
    - 7f0f6c176ac8 = <built-in function setMaxPhysicsFrame>
    - 7f0f6c176c88 = <built-in function getExitKey>
    - 7f0f6c176348 = <built-in function expandPath>
    - 7f0f6c176848 = <built-in function addScene>
    - 7f0f6c176d88 = <built-in function getAverageFrameRate>
    - 7f0f6c176748 = <built-in function getCurrentController>
    - 7f0f6c176488 = <built-in function startGame>
    - 7f0fb8405ca0 = None
    - 7f0f6ededf60 = (dead proxy 'Blender Game Engine data has been freed, cannot use this python variable')
    - 7f0f6c3ed2c8 = [None, None, None, None, None, None, None, None]
    - 7f0f6c1765c8 = <built-in function saveGlobalDict>
    - 7f0f6c176dc8 = <built-in function getBlendFileList>
    - 7f0f6c1768c8 = <built-in function getRandomFloat>
    - 7f0f6c176a48 = <built-in function setMaxLogicFrame>
    - 7f0f6c3f0270 = 'GameLogic.error'
    - 7f0f6c176988 = <built-in function getSpectrum>
    - 7f0f6c176e88 = <built-in function PrintMemInfo>
    - 7f0f6c3eaac0 = 'This is the Python API for the game engine of bge.logic'
    - 7f0f6c1767c8 = <built-in function getSceneList>
    - 7f0f6c176508 = <built-in function endGame>
    - 7f0f6c176948 = <built-in function setGravity>
    - 7f0f6c176c48 = <built-in function setPhysicsTicRate>
    - 7f0f6c176b88 = <built-in function setLogicTicRate>
    - 7f0f6c1766c8 = <built-in function sendMessage>
    - 7f0f6c176e08 = <built-in function PrintGLInfo>
    - 7f0f6c176b08 = <built-in function getLogicTicRate>
    - 7f0f6c176f08 = <built-in function NextFrame>
    - 7f0f6c176f88 = <built-in function getProfileInfo>
    - 7f0f6c176d08 = <built-in function setExitKey>
    - 7f0fb8405ca0 = None
    - 7f0f6c176c08 = <built-in function getPhysicsTicRate>
    - 7f0f6c3ed7c8 = {}
    - 7f0f6c176788 = <built-in function getCurrentScene>
    - 7f0f6c3f0048 = <built-in function LibLoad>
    - 7f0f6c1762b0 = 'GameLogic'
    - 7f0f6c176548 = <built-in function restartGame>
    - 7f0f6c176648 = <built-in function loadGlobalDict>
    - 7f0f6c3f0108 = <built-in function LibList>
    - 7f0f6c3f0088 = <built-in function LibNew>
    - 7f0f6c3f00c8 = <built-in function LibFree>
    - 7f0fb8405ca0 = None
    - 7f0f6c176a88 = <built-in function getMaxPhysicsFrame>

I see two things amiss:

The GameLogic module still exists in memory. It's no longer contained in sys.modules though, I checked that.
Dead proxies can still hold references to other objects.

**Description:** When the BGE quits, there are still remainders of game engine objects in memory. This can be seen when inspecting `gc.get_objects()`. These are probably dead proxies, which apparently can still hold references. ``` >>> import gc ### Before I run the game: >>> o = [repr(o) for o in gc.get_objects()] ### fine, no error. Now I start the BGE, quit it, and do this again: >>> o = [repr(o) for o in gc.get_objects()] Traceback (most recent call last): File "/usr/lib/python3.4/code.py", line 90, in runcode exec(code, self.locals) File "<blender_console>", line 1, in <module> File "<blender_console>", line 1, in <listcomp> SystemError: Blender Game Engine data has been freed, cannot use this python variable ``` **Tested on:** Blender 2.74 and latest version from Git (f8540d7fd5a47bc9d1d676d5aaaa0de379c71637) Running Kubuntu Linux 14.10 64-bit, compiled the version from Git with GCC 4.9.1-16ubuntu6 **To reproduce:** - Open [bge-garbage-test.blend](https://archive.blender.org/developer/F168475/bge-garbage-test.blend) - Run the script and check the terminal for output. It should show a little header and then "Found nothing wrong." - Move the mouse into the 3D view and press P to start the GE. - Press ESC to stop the GE. # Run the script again, and check the terminal for output. On my machine it shows: ``` ============================================================ Performing garbage check ============================================================ Found one: 7f0f6c3edc48 = Blender Game Engine data has been freed, cannot use this python variable Referrers are: - 7f0f881044c8 = (dead proxy 'Blender Game Engine data has been freed, cannot use this python variable') - 7f0f6c3de408 = <module 'GameLogic'> Referents are: - 7f0f6c176a08 = <built-in function getMaxLogicFrame> - 7f0f6cf19750 = (dead proxy 'Blender Game Engine data has been freed, cannot use this python variable') - 7f0f6c176ac8 = <built-in function setMaxPhysicsFrame> - 7f0f6c176c88 = <built-in function getExitKey> - 7f0f6c176348 = <built-in function expandPath> - 7f0f6c176848 = <built-in function addScene> - 7f0f6c176d88 = <built-in function getAverageFrameRate> - 7f0f6c176748 = <built-in function getCurrentController> - 7f0f6c176488 = <built-in function startGame> - 7f0fb8405ca0 = None - 7f0f6ededf60 = (dead proxy 'Blender Game Engine data has been freed, cannot use this python variable') - 7f0f6c3ed2c8 = [None, None, None, None, None, None, None, None] - 7f0f6c1765c8 = <built-in function saveGlobalDict> - 7f0f6c176dc8 = <built-in function getBlendFileList> - 7f0f6c1768c8 = <built-in function getRandomFloat> - 7f0f6c176a48 = <built-in function setMaxLogicFrame> - 7f0f6c3f0270 = 'GameLogic.error' - 7f0f6c176988 = <built-in function getSpectrum> - 7f0f6c176e88 = <built-in function PrintMemInfo> - 7f0f6c3eaac0 = 'This is the Python API for the game engine of bge.logic' - 7f0f6c1767c8 = <built-in function getSceneList> - 7f0f6c176508 = <built-in function endGame> - 7f0f6c176948 = <built-in function setGravity> - 7f0f6c176c48 = <built-in function setPhysicsTicRate> - 7f0f6c176b88 = <built-in function setLogicTicRate> - 7f0f6c1766c8 = <built-in function sendMessage> - 7f0f6c176e08 = <built-in function PrintGLInfo> - 7f0f6c176b08 = <built-in function getLogicTicRate> - 7f0f6c176f08 = <built-in function NextFrame> - 7f0f6c176f88 = <built-in function getProfileInfo> - 7f0f6c176d08 = <built-in function setExitKey> - 7f0fb8405ca0 = None - 7f0f6c176c08 = <built-in function getPhysicsTicRate> - 7f0f6c3ed7c8 = {} - 7f0f6c176788 = <built-in function getCurrentScene> - 7f0f6c3f0048 = <built-in function LibLoad> - 7f0f6c1762b0 = 'GameLogic' - 7f0f6c176548 = <built-in function restartGame> - 7f0f6c176648 = <built-in function loadGlobalDict> - 7f0f6c3f0108 = <built-in function LibList> - 7f0f6c3f0088 = <built-in function LibNew> - 7f0f6c3f00c8 = <built-in function LibFree> - 7f0fb8405ca0 = None - 7f0f6c176a88 = <built-in function getMaxPhysicsFrame> ``` I see two things amiss: - The GameLogic module still exists in memory. It's no longer contained in `sys.modules` though, I checked that. - Dead proxies can still hold references to other objects.

Sybren A. Stüvel commented

2015-04-30 11:18:08 +02:00

Changed status to: 'Open'

Sybren A. Stüvel commented

2015-04-30 11:18:08 +02:00

Added subscribers: @dr.sybren, @brita

Sybren A. Stüvel commented

2015-04-30 11:26:19 +02:00

PS: for fun, press F8 to reload scripts, then run the script again. Boom, Blender crashes (if not, try again).

Angus Hollands commented

2015-05-03 16:54:14 +02:00

Added subscriber: @AngusHollands-4

Angus Hollands commented

2015-05-03 16:54:15 +02:00

We get into a heap of trouble (excuse the pun) because of persistent Python interpreter state, not only for internal objects, but also imported modules (any modules with mutable state that were imported before the engine was run will not be cleared after exit). This can be worked around, but it's a reflection of the issues observed.

Inês Almeida self-assigned this 2015-05-16 20:05:33 +02:00

Aaron Carlisle commented

2015-06-07 02:35:27 +02:00

Added subscriber: @Blendify

Porteries Tristan commented

2015-08-18 12:42:54 +02:00

Added subscriber: @panzergame

Porteries Tristan commented

2015-08-18 12:42:54 +02:00

it seems that the GameLogic module is never freed, if you defined the destructor function you will see that is never called.

blender-admin commented

2015-08-20 12:06:54 +02:00

This issue was referenced by cd24871706

This issue was referenced by cd24871706411b2afd6e098e2b7c95c94bc2de38

Porteries Tristan commented

2015-08-20 12:21:55 +02:00

Changed status from 'Open' to: 'Resolved'

Porteries Tristan closed this issue

2015-08-20 12:21:55 +02:00

blender-admin commented

2015-08-26 11:13:50 +02:00

This issue was referenced by 77ce7eb541

This issue was referenced by 77ce7eb5418e4f0adc5b5d9ac6d67a610f636b59

Sybren A. Stüvel commented

2015-08-26 12:17:36 +02:00

Changed status from 'Resolved' to: 'Open'

Sybren A. Stüvel reopened this issue

2015-08-26 12:17:36 +02:00

Sybren A. Stüvel commented

2015-08-26 12:17:36 +02:00

Commit cd24871706 re-introduced problems with starting the game engine multiple times in the same run of Blender. I have reverted in commit 77ce7eb541.

I've attached a project that shows this issue: #44557-memleak-reloading.tar.bz2. Run the BGE once, and it'll stop immediately (correctly, due to the bge.logic.endGame() call in t44557.bge.submodule2.startup). Run the BGE again, and you'll see a nice error message.

It probably has something to do with the t44557.bge module already getting loaded from Blender, before the BGE starts. However, I feel that we should still support this (and apart from the memory leak, it works fine in current Blender).

Commit cd24871706 re-introduced problems with starting the game engine multiple times in the same run of Blender. I have reverted in commit 77ce7eb5418e4f. I've attached a project that shows this issue: [#44557-memleak-reloading.tar.bz2](https://archive.blender.org/developer/F228110/T44557-memleak-reloading.tar.bz2). Run the BGE once, and it'll stop immediately (correctly, due to the `bge.logic.endGame()` call in `t44557.bge.submodule2.startup`). Run the BGE again, and you'll see a nice error message. It probably has something to do with the `t44557.bge` module already getting loaded from Blender, before the BGE starts. However, I feel that we should still support this (and apart from the memory leak, it works fine in current Blender).

Ulysse Martin commented

2015-11-18 16:10:13 +01:00

Added subscriber: @you.le

Ulysse Martin commented

2015-11-18 16:10:13 +01:00

Hi, I can't reproduce this bug with recent Blender's version... Or I'm missing something? http://www.pasteall.org/pic/95569

Porteries Tristan commented

2016-04-03 17:39:34 +02:00

@dr.sybren, as i understand the GameLogic module is never freed and reused the next frame because it contains only "globalDict" which is set as game end if we just reload an other file.

An other simple test is to do:

    if not hasattr(bge.logic, "a"):
        bge.logic.a = 0
    bge.logic.a = bge.logic.a + 1
    print(dir(bge.logic), bge.logic.a)

And then you will see that "a" is incremented for each run. But i debug the code in some hours and didn't find why it reuse the same module dictionnary because the module pointer and dictionnary is always a new modules, also the system modules dict is the same.
And even if we free the module by doing :

while (gameLogic->ob_refcnt) {
    PyDECREF(gameLogic);
}

The issue is still here.

Trying to import "bge" or "bge.logic" or "GameLogic" outside bge raise an eror as exepted.

@dr.sybren, as i understand the GameLogic module is never freed and reused the next frame because it contains only "globalDict" which is set as game end if we just reload an other file. An other simple test is to do: ``` if not hasattr(bge.logic, "a"): bge.logic.a = 0 bge.logic.a = bge.logic.a + 1 print(dir(bge.logic), bge.logic.a) ``` And then you will see that "a" is incremented for each run. But i debug the code in some hours and didn't find why it reuse the same module dictionnary because the module pointer and dictionnary is always a new modules, also the system modules dict is the same. And even if we free the module by doing : ``` while (gameLogic->ob_refcnt) { PyDECREF(gameLogic); } ``` The issue is still here. Trying to import "bge" or "bge.logic" or "GameLogic" outside bge raise an eror as exepted.

Porteries Tristan commented

2016-04-03 17:45:02 +02:00

Also a big point that i forget : i renamed the folder bge to bge2

Porteries Tristan commented

2016-04-03 18:02:51 +02:00

Apparently clear the sys.modules dictionnary before run the BGE and after run your script make it works. But it means that the BGE can't work on a python "context" modified by blender. So i propose to do like BGE : at blender start make a copy of the sys.modules and when laucnh the BGE load this copied dictionnary.

Porteries Tristan commented

2016-04-03 18:32:57 +02:00

little fix patch : http://www.pasteall.org/67417/diff

Aaron Carlisle commented

2016-04-03 21:35:56 +02:00

Removed subscriber: @Blendify

Angus Hollands commented

2016-04-03 23:15:01 +02:00

We need to be sure that after exiting the game, the original sys.modules entries are returned (your patch would leave the python modules dictionary in the same state as a clean blender instance (not preserving running addons etc)

Porteries Tristan commented

2016-04-04 07:26:09 +02:00

@AngusHollands-4: in the patch we first copy the actual sys.modules then set the clean one and at the game end we restore the copy of the actual sys.modules. So everything is ok.

Aaron Carlisle commented

2019-06-29 02:18:52 +02:00

Changed status from 'Open' to: 'Archived'

Aaron Carlisle closed this issue

2019-06-29 02:18:52 +02:00

Aaron Carlisle commented

2019-06-29 02:18:52 +02:00

This task is being closed because the BGE has been removed in Blender 2.8.

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BGE leaves references in memory after quitting #44557

Run the script again, and check the terminal for output. On my machine it shows: