[tkinter_.py] [Mac] Crashes with message "Segmentation fault: 11"

It often crashes with this message. With system Python it crashes about 50% of the time, with Homebrew Python it crashes 100% of the time.

This error occurs randomly during initial app loading. This issue occurs only on Mac. Below logs:

[tkinter_.py] CEF Python 56.0
[tkinter_.py] Python 2.7.5 
[tkinter_.py] Tk 8.5.9
Segmentation fault: 11

There are some issues with Tk <> CEF initializations, they are conflicting each other. Tk must be initialized before CEF otherwise there was an another error described in Issue #306.

I've tried debugging it using gdb/lldb instructions from KB however I couldn't get a meaningful stack trace. On Linux gdb can show Python stack trace with "py-bt", but I have no idea how to debug this on Mac.

Fix errors in tkinter_.py example on Mac (#306, #308).

I am walking through this under Wing IDE. It fails consistently on my system. The crash happens after the call to app.mainloop(). The window appears, then the crash, with no opportunity for user interaction. With log level set to DEBUG the following appear in the log prior to cef.Initialize():

[tkinter_.py] CEF Python 57.0
[tkinter_.py] Python 3.5.1 64bit
[tkinter_.py] Tk 8.5.9

Upon cef.Initialize() this appears,

[0725/124614.059902:ERROR:child_thread_impl.cc(762)] Request for unknown Channel-associated interface: ui::mojom::GpuMain

(which I think is a red herring). Upon the app.mainloop() call these appear:

[tkinter_.py] MainFrame.on_root_configure
[tkinter_.py] MainFrame.on_root_configure
[tkinter_.py] MainFrame.on_configure
[tkinter_.py] MainFrame.on_root_configure

then the window appears and the segfault happens.

By setting a lot of breakpoints I have verified that everything works fine up until entry to embed_browser() on line 158. The crash happens during

self.browser = cef.CreateBrowserSync(window_info,
                                         url="https://www.google.com/")

I can't debug-step into this (actually I can, but the debugger next surfaces in re.py).

Since the hello_world.py example does not crash, the only difference would seem to be the inclusion of "window_info" in the CreateBrowserSync call. Unfortunately window_info is an opaque object from cefWindowInfo() so I can't tell you what's in it.

However, if I delete the window_info argument from the call, the segfault does not occur.

Note that in both hello_world and tkinter_ examples, the resulting window is blank, there is no display of google.com. Is there supposed to be?

Edit: also the qt.py example works, except that it also displays no web page, here is a screen grab:

When you remove the window_info parameter then you stop embedding browser inside tkinter window, so it stops being a tkinter example and thus it doesn't crash, because CEF creates the root window itself, just like in the hello world example.

A blank window might appear when your Python does not support GUI applications, see this explanation on KB page: https://github.com/cztomczak/cefpython/blob/master/docs/Knowledge-Base.md#a-blank-window-on-maclinux

Thanks for trying to debug this. The only idea I have for this moment would be to play with various tkinter options - global options or window options. Maybe changing some property of the window or some other option would get rid of the error.

Or maybe the code that fetches window handle is not right - see Issue #308. You could try hardcoding the window handle value in the script - but first you would have to obtain such handle. On Linux you can do this using "xdotool" program, for Mac you would need to google that.

My motive in this is to replace QWebEngine in an app based on Python 3.5, PyQt and Qt5.9. The app already works on MacOS, Ubuntu and Windows 7, but the use of QWebEngine prevents bunding it with PyInstaller.

The local Python 3.5 is standard, located in /Library/Frameworks/Python.Framework, as normal when installed from the python.org download. The Mac system Python is at 2.7, located in /System/Library/Frameworks but is not involved in any way.

I haven't touched tkinter in years so hesitate to get into that aspect but will keep poking at this in hopes of learning something useful.

Your issue with a blank window is off-topic here (not a segmentation fault and not a tkinter issue). Please report it on the Forum and I can give you hints how to debug this.

@freegroup

@freegroup Can you post a meaningful stack trace? Is it the same as in this comment #309 (comment) ?

how to get the stacktrace?

Did anyone test tkinter example on Mac with Tk 8.6? That newer version of Tk seems to be more stable with CEF, at least on Windows.

I kept getting segmentation fault 11 every time i opened up a second instance of tk. wtf? well turns out you can only have one instance of tk even though i had destroyed and quit it in the previous module. i avoided this cryptic error by using toplevel instead of creating new root instances each time.. just in case someone had this issue

tkinter example never worked for me on Mac at all. Did you get it working somehow? What version of Tk, python and Mac OS version?

Actually no.. sorry man I hope u get it

[x.py] CEF Python 66.0
[x.py] Python 3.7.5
[x.py] Tk 8.5.9

DevTools listening on ws://127.0.0.1:64947/devtools/browser/
Segmentation fault: 11

2 years! No solution

@tallforasmurf

This still haven't been debugged properly. We need a meaningful stack trace to understand the problem.

@tallforasmurf You've provided stack trace, but the Chromium's part of stack trace does not contain meaningful symbols. You can download CEF symbols from here: http://opensource.spotify.com/cefbuilds/cef_binary_3.3359.1774.gd49d25f_macosx64_release_symbols.tar.bz2

Did anyone test tkinter example on Mac with Tk 8.6? That newer version of Tk seems to be more stable with CEF, at least on Windows.

Python 3.7.7
Tk 8.6.8

no improvement

@tallforasmurf

I was trying to symbolicate the stack trace provided by @tallforasmurf using your .dSYM file.
However, neither in this, nor in a stack trace of my own did I get any output using this command:

dwarfdump --lookup=0x103624000 Chromium\ Embedded\ Framework.dSYM

Does anybody know whether I am doing this wrong?
Just typing

dwarfdump Chromium\ Embedded\ Framework.dSYM

without an address outputs loads and loads of stuff. Using an address from that output works with the above command.

Does anyone have a solution to this issue???

Here is the code that crashes:

  CefBrowserHostView* browser_view = [[CefBrowserHostView alloc] initWithFrame:contentRect];
  browser_view.browser = browser_;
  [parentView addSubview:browser_view];

!! CRASH -->  [browser_view setAutoresizingMask:(NSViewWidthSizable | NSViewHeightSizable)];

  [browser_view setNeedsDisplay:YES];
  [browser_view release];

Ref: https://bitbucket.org/chromiumembedded/cef/src/d49d25f881b68f418e243e12801cbbb7caebb563/libcef/browser/native/browser_platform_delegate_native_mac.mm#lines-214

@interface CefBrowserHostView : NSView {

Apple docs for NSView autoresizingMask:
https://developer.apple.com/documentation/appkit/nsview/1483281-autoresizingmask

Below is a meaningful stack trace for the crash:

Crashed Thread:        0  CrBrowserMain  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x000000005f84b990
Exception Note:        EXC_CORPSE_NOTIFY

Termination Signal:    Segmentation fault: 11
Termination Reason:    Namespace SIGNAL, Code 0xb
Terminating Process:   exc handler [1084]

VM Regions Near 0x5f84b990:
-->
    __TEXT                 000000010073c000-000000010073e000 [    8K] r-x/r-x SM=COW  /System/Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python

Application Specific Information:
objc_msgSend() selector name: addSubview:


Thread 0 Crashed:: CrBrowserMain  Dispatch queue: com.apple.main-thread
0   libobjc.A.dylib               	0x00007fff6d383817 objc_msgSend + 23
1   org.chromium.ContentShell.framework	0x000000010285df57 CefBrowserPlatformDelegateNativeMac::CreateHostWindow() + 711 (browser_platform_delegate_native_mac.mm:214)
2   org.chromium.ContentShell.framework	0x000000010278862d CefBrowserHostImpl::CreateInternal(CefStructBase<CefBrowserSettingsTraits> const&, scoped_refptr<CefClient>, content::WebContents*, scoped_refptr<CefBrowserInfo>, scoped_refptr<CefBrowserHostImpl>, bool, scoped_refptr<CefRequestContext>, std::__1::unique_ptr<CefBrowserPlatformDelegate, std::__1::default_delete<CefBrowserPlatformDelegate> >, scoped_refptr<CefExtension>) + 589 (browser_host_impl.cc:418)
3   org.chromium.ContentShell.framework	0x00000001027881b3 CefBrowserHostImpl::Create(CefBrowserHostImpl::CreateParams&) + 963 (browser_host_impl.cc:359)
4   org.chromium.ContentShell.framework	0x0000000102787cb8 CefBrowserHost::CreateBrowserSync(CefWindowInfo const&, scoped_refptr<CefClient>, CefStringBase<CefStringTraitsUTF16> const&, CefStructBase<CefBrowserSettingsTraits> const&, scoped_refptr<CefRequestContext>) + 744 (browser_host_impl.cc:276)
5   org.chromium.ContentShell.framework	0x0000000100c64b2d cef_browser_host_create_browser_sync + 557 (browser_host_cpptoc.cc:94)
6   cefpython_py27.so             	0x0000000100b22745 CefBrowserHost::CreateBrowserSync(CefWindowInfo const&, scoped_refptr<CefClient>, CefStringBase<CefStringTraitsUTF16> const&, CefStructBase<CefBrowserSettingsTraits> const&, scoped_refptr<CefRequestContext>) + 261
7   cefpython_py27.so             	0x0000000100a66603 __pyx_pf_14cefpython_py27_30CreateBrowserSync(_object*, _object*, _object*, _object*, _object*, _object*) + 10723
8   cefpython_py27.so             	0x0000000100a638fe __pyx_pw_14cefpython_py27_31CreateBrowserSync(_object*, _object*, _object*) + 238
9   org.python.python             	0x00007fff3f6c5ca6 PyEval_EvalFrameEx + 19119
10  org.python.python             	0x00007fff3f6ca68f 0x7fff3f640000 + 566927
11  org.python.python             	0x00007fff3f6c5b00 PyEval_EvalFrameEx + 18697
12  org.python.python             	0x00007fff3f6c0bec PyEval_EvalCodeEx + 531   
...

Fix Mac issues in Tkinter example (#309, #441)

Fixed some of the issues in commit 0da1393 .

There are still startup issues that occur randomly for me and that will be tracked in the newly created issue: #583

Closing this.

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[tkinter_.py] [Mac] Crashes with message "Segmentation fault: 11" #309

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tallforasmurf commented on Jul 25, 2017

tallforasmurf commented on Jul 25, 2017

cztomczak commented on Jul 26, 2017

cztomczak commented on Jul 26, 2017

cztomczak commented on Jul 26, 2017

tallforasmurf commented on Jul 26, 2017

cztomczak commented on Jul 26, 2017

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cztomczak commented on Jun 3, 2019

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cztomczak commented on Jul 20, 2020

cztomczak commented on Jul 20, 2020

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