为什么Model.add（Model.get（））使Django中的“数据库被锁定”错误？

Question

我在应用程序中遇到数据库锁定错误。 （Django，Sqlite3，Window 10）

problem.parent_contest.add(Contest.objects.select_for_update().get(pk=contest))

此语句是否使数据库锁定错误？我不明白为什么该代码会导致错误。请帮助我。

有我的代码和错误回溯。谢谢。

apps.py

for problem_id in range(1000, 19999, 1):
    current_problem = parse_problem(problem_id)
    db_lock.acquire()
    problem, created = Problem.objects.get_or_create(
        id=current_problem['id'],
        defaults={
            'title': current_problem['title'],
            'can_submit': current_problem['can_submit']
        }
    )
    problem.title = current_problem['title']
    problem.can_submit = current_problem['can_submit']
    problem.save()
    for contest in current_problem['parent']:
        problem.parent_contest.add(Contest.objects.select_for_update().get(pk=contest))
    db_lock.release()
time.sleep(600)

models.py

class Contest(models.Model):
    id = models.IntegerField(primary_key=True)
    title = models.TextField()
    parent_category = models.ForeignKey(Category, on_delete=models.CASCADE)

    class Meta:
        ordering = ('id',)

    def __str__(self):
        return 'Contest %s: %s' % (self.id, self.title)


class Problem(models.Model):
    id = models.IntegerField(primary_key=True)
    title = models.TextField()
    can_submit = models.BooleanField()
    parent_contest = models.ManyToManyField(Contest)

    class Meta:
        ordering = ('id',)

    def __str__(self):
        return 'Problem %s: %s' % (self.id, self.title)

引用

Traceback (most recent call last):
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
        return self.cursor.execute(sql, params)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\sqlite3\base.py", line 296, in execute
        return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: database is locked

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
    File "c:\python36\Lib\threading.py", line 916, in _bootstrap_inner
        self.run()
    File "c:\python36\Lib\threading.py", line 864, in run
        self._target(*self._args, **self._kwargs)
    File "C:\msys64\home\JongBeomKim\WEB\ps.kajebiii.com\backend\boj\apps.py", line 150, in parse_all_problem
        problem.parent_contest.add(Contest.objects.select_for_update().get(pk=contest))
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\models\fields\related_descriptors.py", line 926, in add
        self._add_items(self.source_field_name, self.target_field_name, *objs)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\models\fields\related_descriptors.py", line 1093, in _add_items
        for obj_id in new_ids
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\models\query.py", line 465, in bulk_create
        ids = self._batched_insert(objs_without_pk, fields, batch_size)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\models\query.py", line 1152, in _batched_insert
        self._insert(item, fields=fields, using=self.db)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\models\query.py", line 1133, in _insert
        return query.get_compiler(using=using).execute_sql(return_id)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\models\sql\compiler.py", line 1285, in execute_sql
        cursor.execute(sql, params)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\utils.py", line 100, in execute
        return super().execute(sql, params)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\utils.py", line 68, in execute
        return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\utils.py", line 77, in _execute_with_wrappers
        return executor(sql, params, many, context)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
        return self.cursor.execute(sql, params)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\utils.py", line 89, in __exit__
        raise dj_exc_value.with_traceback(traceback) from exc_value
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\utils.py", line 85, in _execute
        return self.cursor.execute(sql, params)
    File "C:\Users\JongBeom Kim\.virtualenvs\backend-3j_oU1lC\lib\site-packages\django\db\backends\sqlite3\base.py", line 296, in execute
        return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: database is locked