As of JDK8-b111, if -XX:+PrintSharedSpaces is specified during -Xshare:dump, in rare occasions, some arrays may be deallocated, and the space re-used later:

#1 0x00007ffff71a9444 in Metaspace::deallocate (this=0x7ffff0035ce8, ptr=0x800009500, word_size=95,
    is_class=false) at /home/iklam/jdk/cds/src/share/vm/memory/metaspace.cpp:3176
#2 0x00007ffff6d6dadc in MetadataFactory::free_array<Method*> (loader_data=0x7ffff0035b88, data=0x800009500)
    at /home/iklam/jdk/cds/src/share/vm/memory/metadataFactory.hpp:70
#3 0x00007ffff6d6a8d5 in merge_in_new_methods (klass=0x80393ef10, new_methods=0x7ffff6715590, __the_thread__=
    0x7ffff000a000) at /home/iklam/jdk/cds/src/share/vm/classfile/defaultMethods.cpp:1092
#4 0x00007ffff6d6a2fd in create_overpasses (slots=0x7ffff0012b58, klass=0x80393ef10,
    __the_thread__=0x7ffff000a000) at /home/iklam/jdk/cds/src/share/vm/classfile/defaultMethods.cpp:990
#5 0x00007ffff6d6966f in DefaultMethods::generate_default_methods (klass=0x80393ef10, mirandas=0x7ffff67158f0,
    __the_thread__=0x7ffff000a000) at /home/iklam/jdk/cds/src/share/vm/classfile/defaultMethods.cpp:785
#6 0x00007ffff6c94be4 in ClassFileParser::parseClassFile (this=0x7ffff6715dd0, name=0x800000240,
    loader_data=0x7ffff0035b88, protection_domain=..., host_klass=..., cp_patches=0x0, parsed_name=...,
    verify=false, __the_thread__=0x7ffff000a000)
    at /home/iklam/jdk/cds/src/share/vm/classfile/classFileParser.cpp:4088
#7 0x00007ffff6ca27c3 in ClassFileParser::parseClassFile (this=0x7ffff6715dd0, name=0x800000240,
    loader_data=0x7ffff0035b88, protection_domain=..., parsed_name=..., verify=false,
    __the_thread__=0x7ffff000a000) at /home/iklam/jdk/cds/src/share/vm/classfile/classFileParser.hpp:468
#8 0x00007ffff6ca0457 in ClassLoader::load_classfile (h_name=0x800000240, __the_thread__=0x7ffff000a000)
    at /home/iklam/jdk/cds/src/share/vm/classfile/classLoader.cpp:941
#9 0x00007ffff736288d in SystemDictionary::load_instance_class (class_name=0x800000240, class_loader=...,
    __the_thread__=0x7ffff000a000) at /home/iklam/jdk/cds/src/share/vm/classfile/systemDictionary.cpp:1335
#10 0x00007ffff736098c in SystemDictionary::resolve_instance_class_or_null (name=0x800000240, class_loader=...,
    protection_domain=..., __the_thread__=0x7ffff000a000)
    at /home/iklam/jdk/cds/src/share/vm/classfile/systemDictionary.cpp:779
#11 0x00007ffff735f2b3 in SystemDictionary::resolve_or_null (class_name=0x800000240, class_loader=...,


Metaspace::record_allocation doesn't consider the case where such deallocation/re-allocation may happen. As a result, -XX:+PrintSharedSpaces may crash here:

DumpAllocClosure::dump_stats(...) {
  ...
  assert(all_ro_bytes == ro_all, "everything should have been counted"); << CRASH HERE
  assert(all_rw_bytes == rw_all, "everything should have been counted");

}