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std::list .size method
I have seen sometimes core files in my application and when I bactraced I found it is coring at executing .size() function on std::list
std::list<std::string> myStringList
myStringList.size() sometimes cores
myStringList is member of static class which has only one instance for the entire application. I understand it should be protected by lock which I am not doing but could .size() on list ever core?
std::list<std::string> myStringList
myStringList.size() sometimes cores
myStringList is member of static class which has only one instance for the entire application. I understand it should be protected by lock which I am not doing but could .size() on list ever core?
C++
Last Comment
learningunix
ASKER
I was looking more into the code, I was having lock when I add entry to the list but when retrieving the size() I don't lock it. Could this cause the core?
Based on my design, yes it is possible one thread can update the list while I am trying to retrieve the size() of the list by other thread
Here's what I see when it execute size() on the list.
Program terminated with signal 11, Segmentation fault.
#0 0x00007f219fff95b1 in std::_List_const_iterator<
221 _M_node = _M_node->_M_next;
(gdb) bt
#0 0x00007f219fff95b1 in std::_List_const_iterator<
#1 0x00007f219fff95e4 in std::__distance<std::_List
#2 0x00007f219fff962d in std::distance<std::_List_c
Based on my design, yes it is possible one thread can update the list while I am trying to retrieve the size() of the list by other thread
Here's what I see when it execute size() on the list.
Program terminated with signal 11, Segmentation fault.
#0 0x00007f219fff95b1 in std::_List_const_iterator<
221 _M_node = _M_node->_M_next;
(gdb) bt
#0 0x00007f219fff95b1 in std::_List_const_iterator<
#1 0x00007f219fff95e4 in std::__distance<std::_List
#2 0x00007f219fff962d in std::distance<std::_List_c
>> it is possible one thread can update the list while I am trying to retrieve the size() of the list by other thread
Then that's a big suspect :)
You will need some way of ensuring this doesn't happen, and proper locking is one such way.
Then that's a big suspect :)
You will need some way of ensuring this doesn't happen, and proper locking is one such way.
ASKER
hmmm... I thought executing .size() on list is just a passive command and this should be ok. looks like my assumption is wrong
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ASKER
Thanks a lot.
What kind of core dump is it ?
Is there a possibility of memory corruption ?
Since you mentioned locking, are multiple threads trying to access the list ?