C++ 程序在试图访问内部映射时崩溃

下面是一个小的读写程序。写入程序将值写入映射的映射，写入成功。 还有另一个进程称为reader，它读取SHM的内容，读取器读取外部映射的键没有问题，但是如果我们试图访问内部映射的内容，它会崩溃。 我已经检查了容器大小，它为case1打印了2，这很好，因为内部映射包含键“case1”的2个元素

然而，当我试图访问内部映射时，程序崩溃，我访问内部映射的方式是否不正确。下面是我正在使用的代码片段

ShmTypedefs.h 核心输出：

(gdb) bt
#0  get_right () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/rbtree_node.hpp:130
#1  next_node () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/tree_algorithms.hpp:441
#2  next_node () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/rbtree_algorithms.hpp:353
#3  operator++ () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/tree_node.hpp:119
#4  prot_incr ()
    at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/interprocess/containers/container/detail/tree.hpp:326
#5  operator++ ()
    at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/interprocess/containers/container/detail/tree.hpp:395
#6  __distance<boost::container::containers_detail::rbtree<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int>, boost::container::containers_detail::select1st<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> >, std::less<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > >, std::allocator<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> > >::iterator> ()
    at /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/stl_iterator_base_funcs.h:79
#7  distance<boost::container::containers_detail::rbtree<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interproce---Type <return> to continue, or q <return> to quit---
ss::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int>, boost::container::containers_detail::select1st<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> >, std::less<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > >, std::allocator<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> > >::iterator> ()
    at /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/stl_iterator_base_funcs.h:114
#8  main () at /home/user/droy/src/quotes/debshmutils/shmmapofmap/src/reader.cxx:33

（gdb）bt
#0在/home/dev/build/third\u party/64-rhel5/boost\u 1\u 47\u 0/include/boost/intrusive/detail/rbtree\u node上获得正确的结果（）。hpp:130
#下一个节点（）位于/home/dev/build/third\u party/64-rhel5/boost\u 1\u 47\u 0/include/boost/intrusive/detail/tree\u algorithms.hpp:441
#下一个节点（）位于/home/dev/build/third\u party/64-rhel5/boost\u 1\u 47\u 0/include/boost/intrusive/rbtree\u algorithms.hpp:353
#3 operator++（）位于/home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/tree_node.hpp:119
#4保护增量（）
位于/home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/interprocess/containers/container/detail/tree.hpp:326
#5运算符++（）
在/home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/interprocess/containers/container/detail/tree.hpp:395
#6距离（）
at/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../../../../../include/c++/4.4.7/bits/stl_迭代器\u base\u funcs.h:79
#7距离（）
在/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../../../../../include/c++/4.4.7/bits/stl_迭代器\u base\u funcs.h:114
#8 main（）位于/home/user/droy/src/quotes/debshmutils/shmmapofmap/src/reader.cxx:33

您映射的类型：

typedef boost::interprocess::map<SharedString, int>  MappedType;

注:

• 您在main中有一个冲突的MySHMMap定义
• 这是非常笨拙的代码

  InnerMapAlloc inner_map_alloc_instance(segment.get_segment_manager());
  
  {
      MappedType& tmp = m_pmap->emplace(key, MappedType(inner_map_alloc_instance)).first->second;
      tmp.emplace(inner_map_key, 2030);
      tmp.emplace(inner_map_key2, 2034);
  }
  
  {
      MappedType& tmp = m_pmap->emplace(key, MappedType(inner_map_alloc_instance)).first->second;
      tmp.emplace(inner_map_key1, 2031);
  }
  
  for (auto const& outer : *m_pmap)
      for (auto const& inner : outer.second)
          std::cout << outer.first << ", " << inner.first << ", " << inner.second << "\n";
  

  我从没听说过这个。你能指出说明这一点的文件吗

---

您的代码太复杂，无法发现可能出错的地方，您能否简化为MWE？（请参见）看起来您想要读取的节点不包含exist@Maciej那么为什么内部映射的大小是2呢？示例很大，但我看到您保存了迭代器。您确定在执行距离函数时它们指向的元素仍然存在吗？代码行为MappedType:：iterator iti=（iter->second）.begin（），MappedType:：iterator iti_end=（iter->second）.end（）；我不认为迭代器失效的可能性，映射的映射在共享内存中，这可能是导致问题的原因吗？Hmmn。我应该有一个MappedType的分配器，就像SharedString一样。让我试试。@deb我已经（为了好玩和荣耀）为你修复了东西的作者端，请参阅更新。我认为你正淹没在共享分配的沼泽中。你能重新考虑一下设计吗？@deb和为了更有趣的事：。我认为这样更容易阅读和维护。

   droy@apdeva01 shmmapofmap> ./bin/reader
    size of map 1
    case1
    Matched case 1
    Size of the inner container is 2 units
    Segmentation fault (core dumped)

(gdb) bt
#0  get_right () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/rbtree_node.hpp:130
#1  next_node () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/tree_algorithms.hpp:441
#2  next_node () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/rbtree_algorithms.hpp:353
#3  operator++ () at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/intrusive/detail/tree_node.hpp:119
#4  prot_incr ()
    at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/interprocess/containers/container/detail/tree.hpp:326
#5  operator++ ()
    at /home/dev/build/third_party/64-rhel5/boost_1_47_0/include/boost/interprocess/containers/container/detail/tree.hpp:395
#6  __distance<boost::container::containers_detail::rbtree<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int>, boost::container::containers_detail::select1st<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> >, std::less<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > >, std::allocator<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> > >::iterator> ()
    at /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/stl_iterator_base_funcs.h:79
#7  distance<boost::container::containers_detail::rbtree<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interproce---Type <return> to continue, or q <return> to quit---
ss::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > >, std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int>, boost::container::containers_detail::select1st<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> >, std::less<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > >, std::allocator<std::pair<boost::container::basic_string<char, std::char_traits<char>, boost::interprocess::allocator<char, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family, boost::interprocess::offset_ptr<void>, 0ul>, boost::interprocess::iset_index> > > const, int> > >::iterator> ()
    at /usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../include/c++/4.4.7/bits/stl_iterator_base_funcs.h:114
#8  main () at /home/user/droy/src/quotes/debshmutils/shmmapofmap/src/reader.cxx:33

typedef boost::interprocess::map<SharedString, int>  MappedType;

typedef boost::interprocess::allocator<std::pair<const SharedString, int>, boost::interprocess::managed_shared_memory::segment_manager > InnerMapAlloc;
typedef boost::interprocess::map<SharedString, int, std::less<SharedString>, InnerMapAlloc>  MappedType;

case1, inner_case1, 2030
case1, inner_case2, 2031
case1, inner_case3, 2034

InnerMapAlloc inner_map_alloc_instance(segment.get_segment_manager());

{
    MappedType& tmp = m_pmap->emplace(key, MappedType(inner_map_alloc_instance)).first->second;
    tmp.emplace(inner_map_key, 2030);
    tmp.emplace(inner_map_key2, 2034);
}

{
    MappedType& tmp = m_pmap->emplace(key, MappedType(inner_map_alloc_instance)).first->second;
    tmp.emplace(inner_map_key1, 2031);
}

for (auto const& outer : *m_pmap)
    for (auto const& inner : outer.second)
        std::cout << outer.first << ", " << inner.first << ", " << inner.second << "\n";

// After construction m_pmap will contain the only object that has been constructed in pmap[0]
// If we construct another object it will goto pmap[1]