Hello there, I think you just hit #29890[0], a bug present in Django in 2.0+ and fixed in Django 2.1.3 which should be released today[1].
Simply updating to 2.1.3 when it's released should address your issue. Cheers, Simon [0] https://code.djangoproject.com/ticket/29890 [1] https://docs.djangoproject.com/en/2.1/releases/2.1.3/ Le jeudi 1 novembre 2018 08:09:13 UTC-4, Han Hu a écrit : > > Here is my model definition > > class Item(models.Model): > name = models.CharField(max_length=256) > > > def item_id_path(instance, filename): > return '{}/{}'.format(instance.item.id, filename) > > > # Create your models here. > class File(models.Model): > file = models.FileField(upload_to=item_id_path) > timestamp = models.DateTimeField(auto_now_add=True) > item = models.ForeignKey(Item, on_delete=models.CASCADE) > > def __str__(self): > return self.file.name > > > The application posts multiples file that belong to the same item. But I > run into race condition in making directories. My server stores all the > related files in a separate folder (named by the item id) together. > > In django/core/files/storage.py _save method it checks the existence of > uploading directory. When multiple files for the same item are uploaded the > first request checks the existence of the directory and is going to create > one, then it switches to the second file upload. It also finds that the > directory doesn't exist yet and it is going to do the same directory > creation. The second file upload will fail because the first file upload > has already created the folder. It fails at the last line of the following > code snippet in storage.py. > > def _save(self, name, content): > full_path = self.path(name) > > # Create any intermediate directories that do not exist. > directory = os.path.dirname(full_path) > if not os.path.exists(directory): > try: > if self.directory_permissions_mode is not None: > # os.makedirs applies the global umask, so we reset it, > # for consistency with file_permissions_mode behavior. > old_umask = os.umask(0) > try: > os.makedirs(directory, self.directory_permissions_mode) > finally: > os.umask(old_umask) > else: > os.makedirs(directory) > > > what approach can I take to avoid this race condition? > > I guess changing the source code from os.makedirs(directory) to > os.makedirs(directory, exist_ok=True) could work. > > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/rest_framework/mixins.py", > > line 21, in create > self.perform_create(serializer) > File "/Users/han/projects/django_maplus_server/rest_api/views.py", line > 27, in perform_create > return super(FileViewSet, self).perform_create(serializer) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/rest_framework/mixins.py", > > line 26, in perform_create > serializer.save() > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/rest_framework/serializers.py", > > line 214, in save > self.instance = self.create(validated_data) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/rest_framework/serializers.py", > > line 940, in create > instance = ModelClass.objects.create(**validated_data) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/manager.py", > > line 82, in manager_method > return getattr(self.get_queryset(), name)(*args, **kwargs) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/query.py", > > line 413, in create > obj.save(force_insert=True, using=self.db) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/base.py", > > line 717, in save > force_update=force_update, update_fields=update_fields) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/base.py", > > line 747, in save_base > updated = self._save_table(raw, cls, force_insert, force_update, > using, update_fields) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/base.py", > > line 830, in _save_table > result = self._do_insert(cls._base_manager, using, fields, update_pk, > raw) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/base.py", > > line 868, in _do_insert > using=using, raw=raw) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/manager.py", > > line 82, in manager_method > return getattr(self.get_queryset(), name)(*args, **kwargs) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/query.py", > > line 1133, in _insert > return query.get_compiler(using=using).execute_sql(return_id) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", > > line 1284, in execute_sql > for sql, params in self.as_sql(): > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", > > line 1237, in as_sql > for obj in self.query.objs > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", > > line 1237, in <listcomp> > for obj in self.query.objs > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", > > line 1236, in <listcomp> > [self.prepare_value(field, self.pre_save_val(field, obj)) for field in > fields] > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/sql/compiler.py", > > line 1188, in pre_save_val > return field.pre_save(obj, add=True) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/fields/files.py", > > line 288, in pre_save > file.save(file.name, file.file, save=False) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/db/models/fields/files.py", > > line 87, in save > self.name = self.storage.save(name, content, > max_length=self.field.max_length) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/core/files/storage.py", > > line 49, in save > return self._save(name, content) > File > "/Users/han/anaconda3/envs/django/lib/python3.6/site-packages/django/core/files/storage.py", > > line 236, in _save > os.makedirs(directory) > File "/Users/han/anaconda3/envs/django/lib/python3.6/os.py", line 220, > in makedirs > mkdir(name, mode) > FileExistsError: [Errno 17] File exists: > -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/0cd8869a-1ef7-4af1-aaa2-1ab3250071b5%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
