From 99a2b7c3470e460a2a01c69ebe6e550792333d30 Mon Sep 17 00:00:00 2001 From: Ran Benita Date: Thu, 2 May 2019 18:46:02 +0300 Subject: [PATCH] Avoid Django's lazy() when creating validators because it is too slow As a fix for issue #3354, commit 607e4edca77441f057ce40cd90175 made the evaluation of some validation error messages lazy. To achieve that, Django's django.utils.functional.lazy() function was used. However, that function is extremely heavy and slow, and slows down string validation significantly (lazy() is evaluated each time for each validator for each field which has one). We noticed this in our production system. Avoid lazy and use a lambda to defer the evaluation instead. This uses the fact that a Django validator is just a simple callable. Using the benchmark attached to the PR (snipped to tottime>100ms): Before, model serializer: 9225123 function calls (9200068 primitive calls) in 8.337 seconds Ordered by: internal time ncalls tottime percall cumtime percall filename:lineno(function) 25000 1.299 0.000 3.534 0.000 functional.py:125(__prepare_class__) 2415001 0.954 0.000 0.954 0.000 {built-in method builtins.hasattr} 1350000 0.901 0.000 0.901 0.000 functional.py:145(__promise__) 1550001 0.521 0.000 0.521 0.000 {built-in method builtins.setattr} 25000 0.494 0.000 0.735 0.000 {built-in method builtins.__build_class__} 30000 0.298 0.000 0.385 0.000 fields.py:297(__init__) 25000 0.289 0.000 5.895 0.000 fields.py:740(__init__) 25000 0.264 0.000 0.802 0.000 field_mapping.py:66(get_field_kwargs) 25000 0.241 0.000 0.241 0.000 functional.py:100(__proxy__) 670003/670001 0.203 0.000 0.211 0.000 {built-in method builtins.getattr} 5000 0.189 0.000 7.722 0.002 serializers.py:990(get_fields) 25000 0.186 0.000 0.400 0.000 functools.py:186(total_ordering) 25000 0.158 0.000 0.299 0.000 functional.py:234(wrapper) 5000 0.129 0.000 0.136 0.000 serializers.py:1066(get_field_names) 25000 0.104 0.000 1.002 0.000 serializers.py:1195(build_standard_field) After, model serializer: 3400123 function calls (3400068 primitive calls) in 2.824 seconds Ordered by: internal time ncalls tottime percall cumtime percall filename:lineno(function) 30000 0.259 0.000 0.341 0.000 fields.py:294(__init__) 25000 0.242 0.000 0.674 0.000 field_mapping.py:66(get_field_kwargs) 5000 0.176 0.000 2.209 0.000 serializers.py:990(get_fields) 25000 0.133 0.000 0.514 0.000 fields.py:737(__init__) 295003/295001 0.106 0.000 0.115 0.000 {built-in method builtins.getattr} Before, regular serializer: 8060003 function calls (7960003 primitive calls) in 7.123 seconds Ordered by: internal time ncalls tottime percall cumtime percall filename:lineno(function) 25000 1.569 0.000 3.897 0.000 functional.py:125(__prepare_class__) 1350000 1.013 0.000 1.013 0.000 functional.py:145(__promise__) 2365000 0.925 0.000 0.925 0.000 {built-in method builtins.hasattr} 1550000 0.512 0.000 0.512 0.000 {built-in method builtins.setattr} 25000 0.378 0.000 0.550 0.000 {built-in method builtins.__build_class__} 25000 0.307 0.000 5.946 0.000 fields.py:740(__init__) 30000 0.277 0.000 0.360 0.000 fields.py:297(__init__) 80000/5000 0.202 0.000 6.526 0.001 copy.py:132(deepcopy) 25000 0.172 0.000 0.172 0.000 functional.py:100(__proxy__) 540000 0.152 0.000 0.152 0.000 {built-in method builtins.getattr} 25000 0.119 0.000 6.199 0.000 fields.py:604(__deepcopy__) After, regular serializer: 2010003 function calls (1935003 primitive calls) in 1.456 seconds Ordered by: internal time ncalls tottime percall cumtime percall filename:lineno(function) 30000 0.194 0.000 0.263 0.000 fields.py:294(__init__) 80000/5000 0.151 0.000 0.923 0.000 copy.py:132(deepcopy) 25000 0.128 0.000 0.470 0.000 fields.py:737(__init__) --- rest_framework/compat.py | 30 ----------- rest_framework/fields.py | 113 +++++++++++++++++++-------------------- tests/conftest.py | 14 +++++ 3 files changed, 69 insertions(+), 88 deletions(-) diff --git a/rest_framework/compat.py b/rest_framework/compat.py index 3068665a8..c9e9adbed 100644 --- a/rest_framework/compat.py +++ b/rest_framework/compat.py @@ -5,7 +5,6 @@ versions of Django/Python, and compatibility wrappers around optional packages. import sys from django.conf import settings -from django.core import validators from django.views.generic import View try: @@ -252,34 +251,5 @@ LONG_SEPARATORS = (', ', ': ') INDENT_SEPARATORS = (',', ': ') -class CustomValidatorMessage: - """ - We need to avoid evaluation of `lazy` translated `message` in `django.core.validators.BaseValidator.__init__`. - https://github.com/django/django/blob/75ed5900321d170debef4ac452b8b3cf8a1c2384/django/core/validators.py#L297 - - Ref: https://github.com/encode/django-rest-framework/pull/5452 - """ - - def __init__(self, *args, **kwargs): - self.message = kwargs.pop('message', self.message) - super().__init__(*args, **kwargs) - - -class MinValueValidator(CustomValidatorMessage, validators.MinValueValidator): - pass - - -class MaxValueValidator(CustomValidatorMessage, validators.MaxValueValidator): - pass - - -class MinLengthValidator(CustomValidatorMessage, validators.MinLengthValidator): - pass - - -class MaxLengthValidator(CustomValidatorMessage, validators.MaxLengthValidator): - pass - - # Version Constants. PY36 = sys.version_info >= (3, 6) diff --git a/rest_framework/fields.py b/rest_framework/fields.py index 5e3132074..6a2df10fd 100644 --- a/rest_framework/fields.py +++ b/rest_framework/fields.py @@ -12,7 +12,8 @@ from django.conf import settings from django.core.exceptions import ObjectDoesNotExist from django.core.exceptions import ValidationError as DjangoValidationError from django.core.validators import ( - EmailValidator, RegexValidator, URLValidator, ip_address_validators + EmailValidator, MaxLengthValidator, MaxValueValidator, MinLengthValidator, + MinValueValidator, RegexValidator, URLValidator, ip_address_validators ) from django.forms import FilePathField as DjangoFilePathField from django.forms import ImageField as DjangoImageField @@ -23,17 +24,13 @@ from django.utils.dateparse import ( from django.utils.duration import duration_string from django.utils.encoding import is_protected_type, smart_text from django.utils.formats import localize_input, sanitize_separators -from django.utils.functional import lazy from django.utils.ipv6 import clean_ipv6_address from django.utils.timezone import utc from django.utils.translation import gettext_lazy as _ from pytz.exceptions import InvalidTimeError from rest_framework import ISO_8601 -from rest_framework.compat import ( - MaxLengthValidator, MaxValueValidator, MinLengthValidator, - MinValueValidator, ProhibitNullCharactersValidator -) +from rest_framework.compat import ProhibitNullCharactersValidator from rest_framework.exceptions import ErrorDetail, ValidationError from rest_framework.settings import api_settings from rest_framework.utils import html, humanize_datetime, json, representation @@ -744,14 +741,15 @@ class CharField(Field): self.min_length = kwargs.pop('min_length', None) super().__init__(**kwargs) if self.max_length is not None: - message = lazy(self.error_messages['max_length'].format, str)(max_length=self.max_length) - self.validators.append( - MaxLengthValidator(self.max_length, message=message)) + self.validators.append(lambda value: MaxLengthValidator( + self.max_length, + message=self.error_messages['max_length'].format(max_length=self.max_length), + )(value)) if self.min_length is not None: - message = lazy( - self.error_messages['min_length'].format, str)(min_length=self.min_length) - self.validators.append( - MinLengthValidator(self.min_length, message=message)) + self.validators.append(lambda value: MinLengthValidator( + self.min_length, + message=self.error_messages['min_length'].format(min_length=self.min_length), + )(value)) # ProhibitNullCharactersValidator is None on Django < 2.0 if ProhibitNullCharactersValidator is not None: @@ -910,15 +908,15 @@ class IntegerField(Field): self.min_value = kwargs.pop('min_value', None) super().__init__(**kwargs) if self.max_value is not None: - message = lazy( - self.error_messages['max_value'].format, str)(max_value=self.max_value) - self.validators.append( - MaxValueValidator(self.max_value, message=message)) + self.validators.append(lambda value: MaxValueValidator( + self.max_value, + message=self.error_messages['max_value'].format(max_value=self.max_value), + )(value)) if self.min_value is not None: - message = lazy( - self.error_messages['min_value'].format, str)(min_value=self.min_value) - self.validators.append( - MinValueValidator(self.min_value, message=message)) + self.validators.append(lambda value: MinValueValidator( + self.min_value, + message=self.error_messages['min_value'].format(min_value=self.min_value), + )(value)) def to_internal_value(self, data): if isinstance(data, str) and len(data) > self.MAX_STRING_LENGTH: @@ -948,17 +946,15 @@ class FloatField(Field): self.min_value = kwargs.pop('min_value', None) super().__init__(**kwargs) if self.max_value is not None: - message = lazy( - self.error_messages['max_value'].format, - str)(max_value=self.max_value) - self.validators.append( - MaxValueValidator(self.max_value, message=message)) + self.validators.append(lambda value: MaxValueValidator( + self.max_value, + message=self.error_messages['max_value'].format(max_value=self.max_value), + )(value)) if self.min_value is not None: - message = lazy( - self.error_messages['min_value'].format, - str)(min_value=self.min_value) - self.validators.append( - MinValueValidator(self.min_value, message=message)) + self.validators.append(lambda value: MinValueValidator( + self.min_value, + message=self.error_messages['min_value'].format(min_value=self.min_value), + )(value)) def to_internal_value(self, data): @@ -1007,16 +1003,15 @@ class DecimalField(Field): super().__init__(**kwargs) if self.max_value is not None: - message = lazy( - self.error_messages['max_value'].format, - str)(max_value=self.max_value) - self.validators.append( - MaxValueValidator(self.max_value, message=message)) + self.validators.append(lambda value: MaxValueValidator( + self.max_value, + message=self.error_messages['max_value'].format(max_value=self.max_value), + )(value)) if self.min_value is not None: - message = lazy( - self.error_messages['min_value'].format, str)(min_value=self.min_value) - self.validators.append( - MinValueValidator(self.min_value, message=message)) + self.validators.append(lambda value: MinValueValidator( + self.min_value, + message=self.error_messages['min_value'].format(min_value=self.min_value), + )(value)) if rounding is not None: valid_roundings = [v for k, v in vars(decimal).items() if k.startswith('ROUND_')] @@ -1352,17 +1347,15 @@ class DurationField(Field): self.min_value = kwargs.pop('min_value', None) super().__init__(**kwargs) if self.max_value is not None: - message = lazy( - self.error_messages['max_value'].format, - str)(max_value=self.max_value) - self.validators.append( - MaxValueValidator(self.max_value, message=message)) + self.validators.append(lambda value: MaxValueValidator( + self.max_value, + message=self.error_messages['max_value'].format(max_value=self.max_value), + )(value)) if self.min_value is not None: - message = lazy( - self.error_messages['min_value'].format, - str)(min_value=self.min_value) - self.validators.append( - MinValueValidator(self.min_value, message=message)) + self.validators.append(lambda value: MinValueValidator( + self.min_value, + message=self.error_messages['min_value'].format(min_value=self.min_value), + )(value)) def to_internal_value(self, value): if isinstance(value, datetime.timedelta): @@ -1605,11 +1598,15 @@ class ListField(Field): super().__init__(*args, **kwargs) self.child.bind(field_name='', parent=self) if self.max_length is not None: - message = self.error_messages['max_length'].format(max_length=self.max_length) - self.validators.append(MaxLengthValidator(self.max_length, message=message)) + self.validators.append(lambda value: MaxLengthValidator( + self.max_length, + message=self.error_messages['max_length'].format(max_length=self.max_length), + )(value)) if self.min_length is not None: - message = self.error_messages['min_length'].format(min_length=self.min_length) - self.validators.append(MinLengthValidator(self.min_length, message=message)) + self.validators.append(lambda value: MinLengthValidator( + self.min_length, + message=self.error_messages['min_length'].format(min_length=self.min_length), + )(value)) def get_value(self, dictionary): if self.field_name not in dictionary: @@ -1876,10 +1873,10 @@ class ModelField(Field): max_length = kwargs.pop('max_length', None) super().__init__(**kwargs) if max_length is not None: - message = lazy( - self.error_messages['max_length'].format, str)(max_length=self.max_length) - self.validators.append( - MaxLengthValidator(self.max_length, message=message)) + self.validators.append(lambda value: MaxLengthValidator( + self.max_length, + message=self.error_messages['max_length'].format(max_length=self.max_length), + )(value)) def to_internal_value(self, data): rel = self.model_field.remote_field diff --git a/tests/conftest.py b/tests/conftest.py index ac29e4a42..b90ac343f 100644 --- a/tests/conftest.py +++ b/tests/conftest.py @@ -95,6 +95,20 @@ def pytest_configure(config): settings.STATIC_ROOT = os.path.join(os.path.dirname(rest_framework.__file__), 'static-root') settings.STATICFILES_STORAGE = 'django.contrib.staticfiles.storage.ManifestStaticFilesStorage' + # Test that serializer fields can be created before django is set-up. + # This is not an ideal place for a test, but what can you do. + # See issue #3354. + from rest_framework.serializers import ( + CharField, DecimalField, DurationField, FloatField, IntegerField, + ListField, + ) + CharField(min_length=1, max_length=2) + IntegerField(min_value=1, max_value=2) + FloatField(min_value=1, max_value=2) + DecimalField(max_digits=10, decimal_places=1, min_value=1, max_value=2) + DurationField(min_value=1, max_value=2) + ListField(min_length=1, max_length=2) + django.setup() if config.getoption('--staticfiles'):