Fixed #7676 -- Modified serializer registration to be thread safe. Thanks to mrts for the patch.

_serializers = {}

def register_serializer(format, serializer_module):

    """Register a new serializer by passing in a module name."""

def register_serializer(format, serializer_module, serializers=None):

    """"Register a new serializer. 

    ``serializer_module`` should be the fully qualified module name

    for the serializer.

    If ``serializers`` is provided, the registration will be added

    to the provided dictionary.

    If ``serializers`` is not provided, the registration will be made

    directly into the global register of serializers. Adding serializers

    directly is not a thread-safe operation.

    """

    module = __import__(serializer_module, {}, {}, [''])

    if serializers is None:

        _serializers[format] = module

    else:

        serializers[format] = module

def unregister_serializer(format):

    """Unregister a given serializer"""

    "Unregister a given serializer. This is not a thread-safe operation."

    del _serializers[format]

def get_serializer(format):

    that user code has a chance to (e.g.) set up custom settings without

    needing to be careful of import order.

    """

    global _serializers

    serializers = {}

    for format in BUILTIN_SERIALIZERS:

        register_serializer(format, BUILTIN_SERIALIZERS[format])

        register_serializer(format, BUILTIN_SERIALIZERS[format], serializers)

    if hasattr(settings, "SERIALIZATION_MODULES"):

        for format in settings.SERIALIZATION_MODULES:

            register_serializer(format, settings.SERIALIZATION_MODULES[format])

            register_serializer(format, settings.SERIALIZATION_MODULES[format], serializers)

    _serializers = serializers