#6  0x000000000075a5be in beast::SystemStats::getStackBacktrace ()
    at src/leveldb/../beast/modules/beast_core/system/SystemStats.cpp:113
#7  0x000000000074c2de in beast::FatalError::FatalError (this=<optimized out>,
    message=0xccf71a "m_pending.get() == 0",
    fileName=0xcdaa48 "src/leveldb/../beast/modules/beast_asio/async/AsyncObject.h", lineNumber=34)
    at src/leveldb/../beast/modules/beast_core/diagnostic/FatalError.cpp:92
#8  0x000000000074c3d3 in beast_reportFatalError (message=message@entry=0xccf71a "m_pending.get() == 0",
    fileName=fileName@entry=0xcdaa48 "src/leveldb/../beast/modules/beast_asio/async/AsyncObject.h",
    lineNumber=lineNumber@entry=34) at src/leveldb/../beast/modules/beast_core/beast_core.cpp:274
#9  0x00000000007c6db2 in ~AsyncObject (this=0x7fff880008f0, __in_chrg=<optimized out>)
    at src/leveldb/../beast/modules/beast_asio/async/AsyncObject.h:34
#10 beast::HTTPClientType::Session::~Session (this=0x7fff880008e0, __in_chrg=<optimized out>)
    at src/leveldb/../beast/modules/beast_asio/http/HTTPClientType.cpp:254
#11 0x00000000007c6deb in beast::HTTPClientType::Session::~Session (this=0x7fff880008e0, __in_chrg=<optimized out>)
    at src/leveldb/../beast/modules/beast_asio/http/HTTPClientType.cpp:265
#12 0x000000000077d52b in beast::SharedObject::destroy (this=<optimized out>)
    at src/leveldb/../beast/modules/beast_core/../../beast/smart_ptr/SharedObject.h:120
#13 0x000000000078820e in beast::SharedObject::decReferenceCount (this=0x7fff880008e0)
    at src/leveldb/../beast/modules/beast_core/../../beast/smart_ptr/SharedObject.h:92
#14 0x00000000007cf6e5 in release (t=<optimized out>)
    at src/leveldb/../beast/modules/beast_core/../../beast/smart_ptr/SharedPtr.h:238
#15 ~SharedPtr (this=0x7fff9b7fd320, __in_chrg=<optimized out>)
    at src/leveldb/../beast/modules/beast_core/../../beast/smart_ptr/SharedPtr.h:197
#16 ~value (this=0x7fff9b7fd320, __in_chrg=<optimized out>) at /usr/include/boost/bind/bind.hpp:112
#17 ~storage1 (this=0x7fff9b7fd320, __in_chrg=<optimized out>) at /usr/include/boost/bind/storage.hpp:40
#18 ~storage2 (this=0x7fff9b7fd320, __in_chrg=<optimized out>) at /usr/include/boost/bind/storage.hpp:107
#19 ~storage3 (this=0x7fff9b7fd320, __in_chrg=<optimized out>) at /usr/include/boost/bind/storage.hpp:125
#20 ~list3 (this=0x7fff9b7fd320, __in_chrg=<optimized out>) at /usr/include/boost/bind/bind.hpp:352
#21 ~bind_t (this=0x7fff9b7fd310, __in_chrg=<optimized out>) at /usr/include/boost/bind/bind.hpp:864
#22 ~WrappedHandler (this=0x7fff9b7fd310, __in_chrg=<optimized out>)
    at src/leveldb/../beast/modules/beast_asio/async/WrapHandler.h:29
#23 ~rewrapped_handler (this=0x7fff9b7fd310, __in_chrg=<optimized out>)
    at /usr/include/boost/asio/detail/wrapped_handler.hpp:140
#24 boost::asio::detail::completion_handler<boost::asio::detail::rewrapped_handler<boost::asio::detail::binder1<boost::asio::detail::wrapped_handler<boost::asio::io_service::strand, beast::detail::WrappedHandler<boost::_bi::bind_t<void, boost::_mfi::mf2<void, beast::HTTPClientType::Session, boost::system::error_code, beast::AsyncObject<beast::HTTPClientType::Session>::CompletionCounter>, boost::_bi::list3<boost::_bi::value<beast::SharedPtr<beast::HTTPClientType::Session> >, boost::arg<1> (*)(), boost::_bi::value<beast::AsyncObject<beast::HTTPClientType::Session>::CompletionCounter> > >, beast::AbstractHandler<void (std::pair<boost::system::error_code, beast::SharedPtr<beast::HTTPResponse> >), std::allocator<char> >&> >, boost::system::error_code>, beast::detail::WrappedHandler<boost::_bi::bind_t<void, boost::_mfi::mf2<void, beast::HTTPClientType::Session, boost::system::error_code, beast::AsyncObject<beast::HTTPClientType::Session>::CompletionCounter>, boost::_bi::list3<boost::_bi::value<beast::SharedPtr<beast::HTTPClientType::Session> >, boost::arg<1> (*)(), boost::_bi::value<beast::AsyncObject<beast::HTTPClientType::Session>::CompletionCounter> > >, beast::AbstractHandler<void (std::pair<boost::system::error_code, beast::SharedPtr<beast::HTTPResponse> >), std::allocator<char> >&> > >::do_complete(boost::asio::detail::task_io_service*, boost::asio::detail::task_io_service_operation*, boost::system::error_code const&, unsigned long) (owner=0x7fff88000c90, base=base@entry=0x7fff8802b0d0)
    at /usr/include/boost/asio/detail/completion_handler.hpp:58