如何閱讀gdb輸出

Question

我正在用Python 3.5编写一个程序，并对所有GUI函数使用PyQt4。当我运行这个程序时，我有时会遇到分割错误。我在网上寻找解决方案，找到了this，它使用gdb。在

我试着用这种方式运行程序，但不知道如何读取输出。谁能给我个提示吗？在

输出：

gdb python3
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
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<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
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Reading symbols from python3...(no debugging symbols found)...done.
(gdb) run GUI3.py 
Starting program: /usr/bin/python3 GUI3.py
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff3ad0700 (LWP 26031)]
[New Thread 0x7ffff12cf700 (LWP 26032)]
[New Thread 0x7fffeeace700 (LWP 26033)]
[New Thread 0x7fffd3da2700 (LWP 26034)]
[New Thread 0x7fffd2042700 (LWP 26035)]
[New Thread 0x7fffd1841700 (LWP 26036)]
[New Thread 0x7fffd1040700 (LWP 26037)]
[New Thread 0x7fffbb952700 (LWP 26038)]
Run function needs to be implemented

Thread 1 "python3" received signal SIGSEGV, Segmentation fault.
QWidgetBackingStore::sync (this=0x1ec5d30) at painting/qbackingstore.cpp:1239
1239    painting/qbackingstore.cpp: No such file or directory.
(gdb) backtrace 
#0  QWidgetBackingStore::sync (this=0x1ec5d30) at painting/qbackingstore.cpp:1239
#1  0x00007fffe0e11c50 in QWidgetPrivate::syncBackingStore (this=0x1907c20)
at kernel/qwidget.cpp:1894
#2  0x00007fffe0e249b8 in QWidget::event (this=this@entry=0x1b3b380, event=event@entry=0x20bab70)
at kernel/qwidget.cpp:8693
#3  0x00007fffe12089b3 in QMainWindow::event (this=0x1b3b380, event=0x20bab70)
at widgets/qmainwindow.cpp:1478
#4  0x00007fffe1cfc28b in ?? ()
   from /usr/lib/python3/dist-packages/PyQt4/QtGui.cpython-35m-x86_64-linux-gnu.so
#5  0x00007fffe0dcdfdc in QApplicationPrivate::notify_helper (this=this@entry=0x18f9d70, 
receiver=receiver@entry=0x1b3b380, e=e@entry=0x20bab70) at kernel/qapplication.cpp:4570
#6  0x00007fffe0dd4f16 in QApplication::notify (this=0x17de970, receiver=0x1b3b380, e=0x20bab70)
at kernel/qapplication.cpp:4356
#7  0x00007fffe1ebc0c6 in ?? ()
   from /usr/lib/python3/dist-packages/PyQt4/QtGui.cpython-35m-x86_64-linux-gnu.so
#8  0x00007fffe2eb390d in QCoreApplication::notifyInternal (this=0x17de970, 
receiver=receiver@entry=0x1b3b380, event=event@entry=0x20bab70)
at kernel/qcoreapplication.cpp:955
#9  0x00007fffe2eb73c6 in QCoreApplication::sendEvent (event=0x20bab70, receiver=0x1b3b380)
at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#10 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, 
event_type=event_type@entry=0, data=0x18fc490) at kernel/qcoreapplication.cpp:1579
#11 0x00007fffe2eb76a3 in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, 
event_type=event_type@entry=0) at kernel/qcoreapplication.cpp:1472
#12 0x00007fffe2ee413e in QCoreApplication::sendPostedEvents ()
at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:236
#13 postEventSourceDispatch (s=0x1900aa0) at kernel/qeventdispatcher_glib.cpp:300
#14 0x00007fffe2a62197 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007fffe2a623f0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#16 0x00007fffe2a6249c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#17 0x00007fffe2ee42ae in QEventDispatcherGlib::processEvents (this=0x17be390, flags=...)
at kernel/qeventdispatcher_glib.cpp:450
#18 0x00007fffe0e7b616 in QGuiEventDispatcherGlib::processEvents (this=<optimised out>, flags=...)
at kernel/qguieventdispatcher_glib.cpp:204
#19 0x00007fffe2eb218f in QEventLoop::processEvents (this=this@entry=0x7fffffffd7d0, flags=...)
at kernel/qeventloop.cpp:149
#20 0x00007fffe2eb24f5 in QEventLoop::exec (this=this@entry=0x7fffffffd7d0, flags=...)
at kernel/qeventloop.cpp:204
#21 0x00007fffe2eb84b9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1227
#22 0x00007fffe1e6aa2b in ?? ()
    from /usr/lib/python3/dist-packages/PyQt4/QtGui.cpython-35m-x86_64-linux-gnu.so
#23 0x00000000004e9b7f in PyCFunction_Call ()
#24 0x00000000005372f4 in PyEval_EvalFrameEx ()
#25 0x0000000000540199 in ?? ()
#26 0x0000000000540e4f in PyEval_EvalCode ()
#27 0x000000000060c272 in ?? ()
#28 0x000000000060e71a in PyRun_FileExFlags ()
#29 0x000000000060ef0c in PyRun_SimpleFileExFlags ()
#30 0x000000000063fb26 in Py_Main ()
#31 0x00000000004cfeb1 in main ()
(gdb) 

Answer 1

Could anyone please give me a hint?

当你看到第三方代码崩溃时libQtGui.so在这种情况下，google栈跟踪的顶部是值得的，希望能找到相关的已经报告的bug，在那里您可以找到解决方法或更新到的版本号。在

在本例中，google QWidgetPrivate::syncBackingStore导致了这个bug https://bugreports.qt.io/browse/QTBUG-41428，它是另一个bug https://bugreports.qt.io/browse/QTBUG-41108的重复。尽管有报道称它是针对Mac操作系统的，但它也可能与x86_64-linux-gnu有关。在

Answer 2

好吧，一个提示：您看到的是调用堆栈。在

作为一个程序员，调用函数（或方法）涉及到将调用的上下文（参数、局部变量、返回地址）添加到内存中称为堆栈的区域。在

因此，您看到的是当分段错误发生时，您的代码（以及不是您的代码）所做的调用（以及尚未返回的调用）。当您的进程得到segfault时，它不会继续执行或“展开”堆栈-它只是转储所有帧。（请注意，框架是从最深到最浅列出的。）

幸运的是，大多数堆栈帧都有运行的函数的名称，因此您可以更好地确定在有问题的段中访问内存的确切位置。不幸的是，堆栈跟踪似乎没有行号（这些行号都是??）的对，因此除了对中构成下一个堆栈帧的函数的调用之外，您无法真正确定它。对您来说也很不幸-看起来大多数/所有这些名称都是PyQT、QT或Python的内置函数，而不是您自己的函数（尽管我在这里可能错了，尤其是如果你超载了）-这也使你更难找出是什么原因导致了这些段错误-因为你可能已经设置了一些值，这些值后来会使不属于你的代码进行无效访问。在