Re: [Boost-users] boost::interprocess segfault when calling pop on deque

On Tue, Jul 27, 2010 at 2:45 PM, Matthew Stump wrote:

I built a datastrucuture which I called BufferedQueue.  It's essentially a double buffered queue but instead of two buffers I allow a user specified number of buffers.  Each buffer is a struct which contains the managed_mapped_file for the particular buffer and a pointer to a boost::interprocess::deque.  Each mapped file contains only 1 deque and the deque is used to store items pushed onto the queue by the user.  I automatically handle rotation between the various buffers when the user calls push or pop.

Specific problem: All of my functional unit tests pass without issue and I have 100% test coverage.  When I run the multi-threaded unit tests I encounter a segfault, but not immediately.  I have some tests which will spawn one thread which instantiates the datastrucutre and will push 100K items onto the queue (this will span multiple buffers).  I spawn a second thread which also instantiates the datastrucutre and begin to pop items off of the queue.  After about 40K items have been poped off of the queue I get a segfault when calling boost::interprocess::deque::pop_front().  It's always on the same line, and occurs when the segment manager is doing it's sanity checks while de-allocating the memory.  Sometimes this occurs when it's the last item in the deque which is being poped, sometimes it's not; there is no detectable pattern.  For my test I'm also using ints so I'm not pushing something onto the datastrucutre that isn't compatible with boost::interprocess.

Any helpful ideas as to what may be the cause of my problem would be greatly appreciated.

// Type declarations for the deque typedef boost::interprocess::managed_mapped_file                    ManagedFile; typedef ManagedFile::segment_manager                                SegmentManager; typedef typename boost::interprocess::allocator  TypeAllocator; typedef typename boost::interprocess::list        MMContainer;

// instantiation of the deque queue = file.find_or_construct<MMContainer>(getBufferName(name, buffNum).c_str())(TypeAllocator(file.get_segment_manager()));

// my pop method template<class T> void BufferedQueue<T>::pop() {    checkBufferCount();

   {        boost::interprocess::sharable_lock<Mutex> master_lock(*m_masterMutex);        boost::interprocess::scoped_lock lock(*getReadBuffer().mutex);

       assert(getReadBuffer().queue);        if (!isBufferEmpty<T>(getReadBuffer()))        {            assert(!getReadBuffer().queue->empty());            getReadBuffer().queue->pop_front();            return;        }    }

   rotate_reader();    boost::interprocess::sharable_lock<Mutex> master_lock(*m_masterMutex);    boost::interprocess::scoped_lock lock(*getReadBuffer().mutex);    if (isBufferEmpty<T>(getReadBuffer()))        throw Exception("called pop() on an empty buffer");

   assert(!getReadBuffer().queue->empty());    getReadBuffer().queue->pop_front(); }

/libs2/external/boost/boost/interprocess/mem_algo/rbtree_best_fit.hpp:1244: void boost::interprocess::rbtree_best_fit::priv_deallocate(void*) [with MutexFamily = boost::interprocess::mutex_family, VoidPointer = boost::interprocess::offset_ptr<void>, unsigned int MemAlignment = 0u]: Assertion `priv_is_allocated_block(block)' failed.

#0  0x0094a410 in __kernel_vsyscall () #1  0x02850df0 in raise () from /lib/libc.so.6 #2  0x02852701 in abort () from /lib/libc.so.6 #3  0x0284a26b in __assert_fail () from /lib/libc.so.6 #4  0x0806ca9f in boost::interprocess::rbtree_best_fit::priv_deallocate (this=0xb5fcd004, addr=0xb5fcd0b8)    at /libs2/external/boost/boost/interprocess/mem_algo/rbtree_best_fit.hpp:1244 #5  0x0807b00b in boost::interprocess::rbtree_best_fit::deallocate (this=0xb5fcd004, addr=0xb5fcd0b8)    at /libs2/external/boost/boost/interprocess/mem_algo/rbtree_best_fit.hpp:1233 #6  0x0807b05f in boost::interprocess::segment_manager_base >::deallocate    (this=0xb5fcd004, addr=0xb5fcd0b8) at /libs2/external/boost/boost/interprocess/segment_manager.hpp:217 #7  0x0807b5fe in boost::interprocess::allocator, boost::interprocess::segment_manager, boost::interprocess::iset_index> >::deallocate (this=0xb5fcd0b0, ptr=...)    at /libs2/external/boost/boost/interprocess/allocators/allocator.hpp:152 #8  0x0807b61c in boost::interprocess::allocator, boost::interprocess::segment_manager, boost::interprocess::iset_index> >::deallocate_one (this=0xb5fcd0b0, p=...)    at /libs2/external/boost/boost/interprocess/allocators/allocator.hpp:234 #9  0x0807b693 in boost::container::containers_detail::allocator_destroyer, boost::interprocess::segment_manager, boost::interprocess::iset_index> > >::priv_deallocate (this=0x43511dc, p=...) at /libs2/external/boost/boost/interprocess/containers/container/detail/destroyers.hpp:133 #10 0x0807b6ca in boost::container::containers_detail::allocator_destroyer, boost::interprocess::segment_manager, boost::interprocess::iset_index> > >::operator() (this=0x43511dc, p=...) at /libs2/external/boost/boost/interprocess/containers/container/detail/destroyers.hpp:143 #11 0x0807b786 in boost::intrusive::list_impl, boost::intrusive::list_node_traits, normal_link, boost::intrusive::default_tag, 1>, unsigned int, true> >::erase_and_dispose, boost::interprocess::segment_manager, boost::interprocess::iset_index> > > > (    this=0xb5fcd0b4, i=..., disposer=...) at /libs2/external/boost/boost/intrusive/list.hpp:649 #12 0x0807b7ce in boost::intrusive::list_impl, boost::intrusive::list_node_traits, normal_link, boost::intrusive::default_tag, 1>, unsigned int, true> >::erase_and_dispose, boost::interprocess::segment_manager, boost::interprocess::iset_index> > > > (    this=0xb5fcd0b4, i=..., disposer=...) at /libs2/external/boost/boost/intrusive/list.hpp:656 #13 0x0807b839 in boost::container::list, boost::interprocess::iset_index> > >::erase (this=0xb5fcd0b0, p=...)    at /libs2/external/boost/boost/interprocess/containers/container/list.hpp:930 #14 0x0807b881 in boost::container::list, boost::interprocess::iset_index> > >::pop_front (this=0xb5fcd0b0)    at /libs2/external/boost/boost/interprocess/containers/container/list.hpp:623 #15 0x0808a2e2 in Ovid::BufferedQueue<int>::pop (this=0x43512f0) at /ovid/server/shared/ovidserver-bufferedqueue.cpp:287 #16 0x080557fb in reader_multithread_two_writer_single_reader_throughput () at test-ovidserver-bufferedqueue.cpp:389 #17 0x07653832 in start_thread () from /lib/libpthread.so.0 #18 0x028f9e0e in clone () from /lib/libc.so.6

It is best if you can supply a completely self-contained (using boost of course) example that demonstrates the issue.