c++ - 为什么我的应用程序在关闭时有时会因 SIGSEGV 而崩溃？

Question

我用 C++ 编写了一个应用程序，它使用 Qt 4.7.4。启动时，它会加载一些自己编写的动态库，这些库也使用 Qt(如果这在某种程度上有用的话)。

关闭应用程序时，有时它会因 SIGSEGV 和以下回溯而崩溃:

#0  malloc_consolidate (av=0x7ffff58b21c0) at malloc.c:5155
#1  0x00007ffff5591659 in malloc_consolidate (av=0x7ffff58b21c0) at malloc.c:5115
#2  _int_free (av=0x7ffff58b21c0, p=<optimized out>) at malloc.c:5034
#3  0x00007ffff5594d7c in __GI___libc_free (mem=<optimized out>) at malloc.c:3738
#4  0x00007ffff5e9e0ac in QString::free (d=0xdb0290) at tools/qstring.cpp:1186
#5  0x00007fffe60b3d83 in ~QString (this=0xba0328, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qstring.h:883
#6  node_destruct (to=0xba0328, from=0xba0328, this=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qlist.h:420
#7  QList<QString>::free (data=0xba0310, this=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qlist.h:744
#8  0x00007fffe60c2b49 in ~QList (this=0xba0388, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qlist.h:719
#9  ~QStringList (this=0xba0388, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qstringlist.h:66
#10 ~SignalHook (this=0xba0358, __in_chrg=<optimized out>) at qdbusconnection_p.h:121
#11 ~QHashNode (this=0xba0340, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qhash.h:216
#12 QHash<QString, QDBusConnectionPrivate::SignalHook>::deleteNode2 (node=0xba0340) at ../../include/QtCore/../../src/corelib/tools/qhash.h:519
#13 0x00007ffff5e754da in QHashData::free_helper (this=0xd8aec0, node_delete=0x7fffe60c2ae0 <QHash<QString, QDBusConnectionPrivate::SignalHook>::deleteNode2(QHashData::Node*)>) at tools/qhash.cpp:271
#14 0x00007fffe60ba733 in freeData (x=<optimized out>, this=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qhash.h:568
#15 ~QHash (this=<optimized out>, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qhash.h:284
#16 ~QMultiHash (this=0xba3498, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qhash.h:922
#17 ~QMultiHash (this=0xba3498, __in_chrg=<optimized out>) at qdbusintegrator.cpp:998
#18 QDBusConnectionPrivate::~QDBusConnectionPrivate (this=0xba33f0, __in_chrg=<optimized out>) at qdbusintegrator.cpp:998
#19 0x00007fffe60ba939 in QDBusConnectionPrivate::~QDBusConnectionPrivate (this=0xba33f0, __in_chrg=<optimized out>) at qdbusintegrator.cpp:1016
#20 0x00007fffe60afe43 in ~QDBusDefaultConnection (this=0xba55a0, __in_chrg=<optimized out>) at qdbusconnection.cpp:993
#21 QGlobalStaticDeleter<QDBusDefaultConnection>::~QGlobalStaticDeleter (this=0x7fffe63102f8, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/global/qglobal.h:1825
#22 0x00007ffff5553821 in __run_exit_handlers (status=0, listp=0x7ffff58b05a8, run_list_atexit=true) at exit.c:78
#23 0x00007ffff55538a5 in __GI_exit (status=<optimized out>) at exit.c:100
#24 0x00007ffff5539314 in __libc_start_main (main=0x493935 <main(int, char**)>, argc=1, ubp_av=0x7fffffffde58, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffde48) at libc-start.c:258
#25 0x0000000000421a99 in _start ()

有时是这个

#0  malloc_consolidate (av=0x7ffff58b21c0) at malloc.c:5155
#1  0x00007ffff5591659 in malloc_consolidate (av=0x7ffff58b21c0) at malloc.c:5115
#2  _int_free (av=0x7ffff58b21c0, p=<optimized out>) at malloc.c:5034
#3  0x00007ffff5594d7c in __GI___libc_free (mem=<optimized out>) at malloc.c:3738
#4  0x00007ffff5f4d5a9 in ~QVector (this=0x767c40, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qvector.h:119
#5  QGlobalStaticDeleter<QVector<QCustomTypeInfo> >::~QGlobalStaticDeleter (this=0x7ffff6274898, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/global/qglobal.h:1825
#6  0x00007ffff5553c3d in __cxa_finalize (d=0x7ffff6273d20) at cxa_finalize.c:56
#7  0x00007ffff5e3e0a6 in __do_global_dtors_aux () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#8  0x00007fffffffd7c0 in ?? ()
#9  0x00007fffffffdd30 in ?? ()
#10 0x00007ffff5f9e5a1 in _fini () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4
#11 0x000000000000009f in ?? ()
#12 0x00007ffff7deb105 in ?? () from /lib64/ld-linux-x86-64.so.2

或者这个

#0  malloc_consolidate (av=0x7ffff58b21c0) at malloc.c:5155
#1  0x00007ffff5591659 in malloc_consolidate (av=0x7ffff58b21c0) at malloc.c:5115
#2  _int_free (av=0x7ffff58b21c0, p=<optimized out>) at malloc.c:5034
#3  0x00007ffff5594d7c in __GI___libc_free (mem=<optimized out>) at malloc.c:3738
#4  0x00007ffff5e86bbe in freeData (x=<optimized out>, this=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qmap.h:654
#5  ~QMap (this=0x10af198, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qmap.h:187
#6  ~QMap (this=0x10af198, __in_chrg=<optimized out>) at tools/qvector.h:430
#7  ~QRegExpAutomatonState (this=0x10af180, __in_chrg=<optimized out>) at tools/qregexp.cpp:947
#8  QVector<QRegExpAutomatonState>::free (x=0x10af0f0, this=<optimized out>) at tools/qvector.h:438
#9  0x00007ffff5e969a9 in clear (this=<optimized out>) at tools/qcache.h:139
#10 ~QCache (this=<optimized out>, __in_chrg=<optimized out>) at tools/qcache.h:103
#11 QGlobalStaticDeleter<QCache<QRegExpEngineKey, QRegExpEngine> >::~QGlobalStaticDeleter (this=0x7ffff6274368, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/global/qglobal.h:1825
#12 0x00007ffff5553821 in __run_exit_handlers (status=0, listp=0x7ffff58b05a8, run_list_atexit=true) at exit.c:78
#13 0x00007ffff55538a5 in __GI_exit (status=<optimized out>) at exit.c:100
#14 0x00007ffff5539314 in __libc_start_main (main=0x493935 <main(int, char**)>, argc=1, ubp_av=0x7fffffffde58, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffde48) at libc-start.c:258
#15 0x0000000000421a99 in _start ()

还有一些……

我认为它们都是相关的，但我真的无法弄清楚这是如何发生的以及为什么会发生(请注意，没有任何痕迹列出我的任何代码)。

非常感谢您提供一些提示，说明为什么会发生这种情况或我应该从哪里开始搜索。

Answer 1

我找到了问题的解决方案:我将一个静态库链接到我的主应用程序和我的动态库。这个静态库使用的是使用全局变量的 Qt。在应用程序关闭时，动态库已从我的应用程序中卸载。这导致删除了 Qt 的全局变量。但是应用程序本身的关闭导致再次删除以 SIGSEGV 结尾的相同全局变量。

解决方案是将静态库更改为动态库。现在全局变量只被删除一次，因为所有共享库和主应用程序都使用“相同”的 Qt 代码。