在我的Django项目中，我认为，当用户发布一个zip文件时，它将立即回复，然后在线程的帮助下在后台处理数据。该视图在正常测试中工作正常，但是当我运行Django的测试时，该视图失败，并显示database table is locked错误。当前，我正在使用默认的SQLite数据库，并且我知道如果我切换到另一个数据库可以解决此问题，但是我正在寻找当前设置的答案。我为简化起见修剪了代码。
似乎问题在于写入DeviceReportModel表中。但是我不确定为什么TestDeviceReport访问它。
Model.py：
class DeviceReportModel(models.Model):
device_id = models.PositiveIntegerField(primary_key=True)
ip = models.GenericIPAddressField()
created_time = models.DateTimeField(default=timezone.now)
report_file = models.FileField(upload_to="DeviceReport")
device_datas = models.ManyToManyField(DeviceDataReportModel)
def __str__(self):
return str(self.id)
Serializers.py：
class DeviceReportSerializer(serializers.ModelSerializer):
class Meta:
model = DeviceReportModel
fields = '__all__'
read_only_fields = ('created_time', 'ip', 'device_datas')
views.py：
from django.utils import timezone
from django.core.files.base import ContentFile
from rest_framework.response import Response
from rest_framework import status, generics
import time
import threading
from queue import Queue
class DeviceReportHandler:
ReportQueue = Queue()
@staticmethod
def save_datas(device_object, request_ip, b64datas):
device_data_models = []
# ...
# process device_data_models
# this will take some time
time.sleep(10)
return device_data_models
@classmethod
def Check(cls):
while(True):
if not cls.ReportQueue.empty():
report = cls.ReportQueue.get()
# ...
report_model = DeviceReportModel(
device_id=report['device_object'], ip=report['request_ip'])
# THIS LINE GIVES ERROR
report_model.report_file.save(
"Report_{}.txt.gz".format(timezone.now()), ContentFile(report['report_data']))
device_data_models = cls.save_datas(
report['device_object'], report['request_ip'], 'SomeData')
report_model.device_datas.set(device_data_models)
report_model.save()
print("Report Handle Done")
time.sleep(.1)
@classmethod
def run(cls):
thr = threading.Thread(target=cls.Check)
thr.daemon = True
thr.start()
class DeviceReportView(generics.ListCreateAPIView):
queryset = DeviceReportModel.objects.all()
serializer_class = DeviceReportSerializer
DeviceReportHandler.run()
def post(self, request):
# ...
report = {
'device_object': 1,
'request_ip': '0.0.0.0',
'report_data': b'Some report plain data',
}
# add request to ReportQueue
DeviceReportHandler.ReportQueue.put(report)
return Response("OK", status.HTTP_201_CREATED)
tests.py：
from rest_framework.test import APITestCase
import gzip
from io import BytesIO
import base64
import time
class TestDeviceReport(APITestCase):
@classmethod
def setUpTestData(cls):
# add a new test device for other tests
pass
def generate_device_data(self):
# generate fake device data
return ""
def test_Report(self):
# generate device data
device_data = ''
for i in range(10):
device_data += self.generate_device_data() + '\n'
buf = BytesIO()
compressed = gzip.GzipFile(fileobj=buf, mode="wb")
compressed.write(device_data.encode())
compressed.close()
b64data = base64.b64encode(buf.getvalue()).decode()
data = {
"device_id": 1,
"report_data": b64data
}
response = self.client.post(
'/device/reports/', data=data, format='json')
print(response.status_code, response.content)
def tearDown(self):
# put some sleep to check whether the data has been processed
# see "Report Handle Done"
time.sleep(10)
这是错误日志：
(myDjangoEnv) python manage.py test deviceApp.tests.tests.TestDeviceReport
Creating test database for alias 'default'...
System check identified no issues (0 silenced).
201 b'"OK"'
Exception in thread Thread-1:
Traceback (most recent call last):
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\sqlite3\base.py", line 383, in execute
return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: database table is locked
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\threading.py", line 917, in _bootstrap_inner
self.run()
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\threading.py", line 865, in run
self._target(*self._args, **self._kwargs)
File "<project_path>\deviceApp\views.py", line 303, in Check
"Report_{}.txt.gz".format(timezone.now()), ContentFile(report['report_data']))
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\fields\files.py", line 93, in save
self.instance.save()
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\base.py", line 741, in save
force_update=force_update, update_fields=update_fields)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\base.py", line 779, in save_base
force_update, using, update_fields,
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\base.py", line 870, in _save_table
result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\base.py", line 908, in _do_insert
using=using, raw=raw)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\manager.py", line 82, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\query.py", line 1186, in _insert
return query.get_compiler(using=using).execute_sql(return_id)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\models\sql\compiler.py", line 1335, in execute_sql
cursor.execute(sql, params)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 67, in execute
return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 76, in _execute_with_wrappers
return executor(sql, params, many, context)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\utils.py", line 89, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\utils.py", line 84, in _execute
return self.cursor.execute(sql, params)
File "C:\Users\Masoud\Anaconda3\envs\myDjangoEnv\lib\site-packages\django\db\backends\sqlite3\base.py", line 383, in execute
return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: database table is locked
.
----------------------------------------------------------------------
Ran 1 test in 10.023s
OK
Destroying test database for alias 'default'...
答案 0 :(得分：0)
数据库已锁定错误
SQLite旨在成为轻量级数据库，因此不支持高级别的并发性。 OperationalError：数据库已锁定错误，表明您的应用程序并发性高于sqlite在默认配置下无法处理的并发性。此错误意味着一个线程或进程在数据库连接上具有排他锁，而另一个线程在等待释放锁时超时。
Python的SQLite包装器具有默认的超时值，该值确定第二个线程在超时之前允许等待多长时间，并引发OperationalError：数据库被锁定错误。
如果遇到此错误，可以通过以下方法解决：
切换到另一个数据库后端。在某些时候，SQLite对于实际应用程序来说太“精简”了，这些并发错误表明您已经达到了这一点。
重写代码以减少并发性，并确保数据库事务是短暂的。
通过设置超时数据库选项来增加默认超时值：
'OPTIONS': {
# ...
'timeout': 20,
# ...
}
这将使SQLite等待更长的时间，然后再引发“数据库已锁定”错误；它并不会真正解决它们。
https://docs.djangoproject.com/en/3.0/ref/databases/#database-is-locked-errorsoption