Unity8 crashed for me and I did a top and media-hub-service was using 96% cpu
I attached to it with gdb and this is what it's doing:

(gdb) bt
#0  0xb6a08712 in epoll_wait () from /lib/arm-linux-gnueabihf/libc.so.6
#1  0xb6ecf422 in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#2  0xb6ed12be in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#3  0xb6ed168e in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#4  0xb6eba92c in core::dbus::Bus::run() () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#5  0x000d8f16 in main ()
(gdb) t a a bt

Thread 7 (Thread 0xb52683e0 (LWP 2490)):
#-1 0xb66bf840 in ?? ()
Backtrace stopped: Cannot access memory at address 0x78696e6c

Thread 6 (Thread 0xb48ff3e0 (LWP 2493)):
#0  0xb66bf840 in ?? ()
#1  0xb66d329c in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 5 (Thread 0xb3eff3e0 (LWP 2499)):
#0  0xb6a70554 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
#1  0xb6a6e1e4 in __lll_lock_wait () from /lib/arm-linux-gnueabihf/libpthread.so.0
#2  0xb6a6a840 in pthread_mutex_lock () from /lib/arm-linux-gnueabihf/libpthread.so.0
#3  0x000de3a8 in std::mutex::lock() ()
#4  0x000e39de in core::Signal<void>::~Signal() ()
#5  0x0012f704 in gstreamer::Engine::Private::~Private() ()
#6  0x0012ae92 in gstreamer::Engine::~Engine() ()
#7  0x000d9692 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() ()
#8  0x00121604 in std::_Sp_counted_ptr_inplace<core::ubuntu::media::PlayerImplementation::Private, std::allocator<core::ubuntu::media::PlayerImplementation::Private>, (__gnu_cxx::_Lock_policy)2>::_M_dispose() ()
#9  0x000d9692 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() ()
#10 0x0011f3ec in core::ubuntu::media::PlayerImplementation::~PlayerImplementation() ()
#11 0x000d9692 in std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release() ()
#12 0x000d9ae4 in core::ubuntu::media::ServiceSkeleton::remove_player_for_key(unsigned int const&)
    ()
#13 0x00118be0 in ?? ()
#14 0xb6ed13b0 in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#15 0xb6ed168e in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#16 0xb6eba92c in core::dbus::Bus::run() () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#17 0xb6b38360 in ?? () from /usr/lib/arm-linux-gnueabihf/libstdc++.so.6
#18 0xb6a68f98 in start_thread () from /lib/arm-linux-gnueabihf/libpthread.so.0
---Type <return> to continue, or q <return> to quit---
#19 0xb6a0822c in ?? () from /lib/arm-linux-gnueabihf/libc.so.6
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 4 (Thread 0xb31943e0 (LWP 4713)):
#0  0xb6a70556 in __libc_do_syscall () from /lib/arm-linux-gnueabihf/libpthread.so.0
#1  0xb6a6e1e4 in __lll_lock_wait () from /lib/arm-linux-gnueabihf/libpthread.so.0
#2  0xb6a6a840 in pthread_mutex_lock () from /lib/arm-linux-gnueabihf/libpthread.so.0
#3  0x000de3a8 in std::mutex::lock() ()
#4  0x0011f064 in ?? ()
#5  0x000e390c in core::Signal<void>::operator()() ()
#6  0x000e390c in core::Signal<void>::operator()() ()
#7  0xb673a15e in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 3 (Thread 0xacbff3e0 (LWP 4714)):
#0  0xb66bf840 in ?? ()
#1  0xb66d329c in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 2 (Thread 0xaddff3e0 (LWP 4715)):
#0  0xb66bf840 in ?? ()
#1  0xb66d329c in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

Thread 1 (Thread 0xb6f79000 (LWP 2423)):
#0  0xb6a08712 in epoll_wait () from /lib/arm-linux-gnueabihf/libc.so.6
#1  0xb6ecf422 in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#2  0xb6ed12be in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#3  0xb6ed168e in ?? () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#4  0xb6eba92c in core::dbus::Bus::run() () from /usr/lib/arm-linux-gnueabihf/libdbus-cpp.so.4
#5  0x000d8f16 in main ()
(gdb)