我正在使用一个开源Django应用程序，它将所有请求记录到模型中。它存储路径，IP，用户，查询集等等。然而，我有兴趣看看哪条路径花费的时间最长，所以我可以优化它们，但应用程序不会存储显式的开始和结束时间。处理请求，因此我想扩展此模型以无需添加任何新模型即可无缝支持此功能。
Django应用程序的维护者不想添加此功能，我不想分叉，扩展它，并维护一个完全独立的应用程序。所以我决定通过使用Django的class_prepared信号动态添加几个字段以及使用Django的post_save信号更新这些字段值的自定义保存过程来实现这些新功能。
我的代码如下：
from django.db.models.signals import class_prepared, post_save
def add_request_fields(sender, **kwargs):
"""
class_prepared signal handler that checks for the model named
MyModel as the sender, and adds a CharField
to it.
"""
if sender.__name__ == 'Request':
# Create a field to record when we first receive the request.
field = DateTimeField(_('start time'), default=None, db_index=True, blank=True, null=True, editable=False)
field.contribute_to_class(sender, 'start_time')
# Create a field to record to total seconds it takes to process a request.
field = FloatField(_('total seconds'), default=None, db_index=True, blank=True, null=True, editable=False)
field.contribute_to_class(sender, 'total_seconds')
# Re-name default time field with a more accurate label.
sender._meta.get_field('time').verbose_name = 'end time'
class_prepared.connect(add_request_fields)
def post_request_save(sender, instance, **kwargs):
"""
When the request instance is created, update its timestamp to calculate the total seconds taken to process the request.
"""
if sender.__name__ == 'Request':
# Request has to be imported here, instead of at the file's top-level, otherwise it breaks the custom field additions.
from request.models import Request
start_time = get_current_request_start() # Custom method that uses its own middleware to record the start time of each request.
total_seconds = None
if start_time and instance.time:
total_seconds = (instance.time - start_time).total_seconds()
Request.objects.filter(id=instance.id).update(start_time=start_time, total_seconds=total_seconds)
post_save.connect(post_request_save)
这在使用dev服务器进行手动测试时似乎运行良好，但现在当我运行我的unittest套件时，由于随机点的分段错误，Python正在崩溃。我唯一改变的是添加了这段代码，所以这可能是某种程度上造成的。为什么会这样？
我的实施或任何其他问题是否存在潜在的内存泄漏？有没有更好的方法来实现这个功能？
编辑：如果我在gdb内运行我的测试并捕获回溯，那么这就是输出：
Thread 1 "python" received signal SIGSEGV, Segmentation fault.
0x00007fffe41dcad8 in ?? () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
(gdb) backtrace
#0 0x00007fffe41dcad8 in ?? () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
#1 0x00007fffe4216f0a in ?? () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
#2 0x00007fffe42185f9 in ?? () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
#3 0x00007fffe421ac24 in ?? () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
#4 0x00007fffe423f2c1 in ?? () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
#5 0x00007fffe42441a7 in sqlite3_step () from /usr/lib/x86_64-linux-gnu/libsqlite3.so.0
#6 0x00007fffcfff707e in pysqlite_step () from /home/chris/git/myproject/.env/lib/python2.7/lib-dynload/_sqlite3.x86_64-linux-gnu.so
#7 0x00007fffcfffa40d in _pysqlite_query_execute () from /home/chris/git/myproject/.env/lib/python2.7/lib-dynload/_sqlite3.x86_64-linux-gnu.so
#8 0x00000000004a577e in PyObject_Call ()
#9 0x00000000004c5e10 in PyEval_CallObjectWithKeywords ()
#10 0x0000000000537613 in ?? ()
#11 0x00000000004c15bf in PyEval_EvalFrameEx ()
#12 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#13 0x00000000004c16e7 in PyEval_EvalFrameEx ()
#14 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#15 0x00000000004c16e7 in PyEval_EvalFrameEx ()
#16 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#17 0x00000000004c16e7 in PyEval_EvalFrameEx ()
#18 0x00000000004c136f in PyEval_EvalFrameEx ()
#19 0x00000000004c136f in PyEval_EvalFrameEx ()
#20 0x00000000004c136f in PyEval_EvalFrameEx ()
#21 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#22 0x00000000004c1e6f in PyEval_EvalFrameEx ()
#23 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#24 0x00000000004c1e6f in PyEval_EvalFrameEx ()
#25 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#26 0x00000000004c1e6f in PyEval_EvalFrameEx ()
#27 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#28 0x00000000004d54b9 in ?? ()
#29 0x00000000004eebee in ?? ()
#30 0x00000000004a577e in PyObject_Call ()
#31 0x0000000000548253 in ?? ()
#32 0x00000000004c15bf in PyEval_EvalFrameEx ()
#33 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#34 0x00000000004d55f3 in ?? ()
#35 0x00000000004a577e in PyObject_Call ()
#36 0x00000000004bed3d in PyEval_EvalFrameEx ()
#37 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#38 0x00000000004d54b9 in ?? ()
#39 0x00000000004eebee in ?? ()
#40 0x00000000004a577e in PyObject_Call ()
#41 0x0000000000548253 in ?? ()
#42 0x00000000004c15bf in PyEval_EvalFrameEx ()
#43 0x00000000004c136f in PyEval_EvalFrameEx ()
#44 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#45 0x00000000004c1e6f in PyEval_EvalFrameEx ()
#46 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#47 0x00000000004c16e7 in PyEval_EvalFrameEx ()
#48 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#49 0x00000000004d55f3 in ?? ()
#50 0x00000000004a577e in PyObject_Call ()
#51 0x00000000004bed3d in PyEval_EvalFrameEx ()
#52 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#53 0x00000000004d55f3 in ?? ()
---Type <return> to continue, or q <return> to quit---
#54 0x00000000004a577e in PyObject_Call ()
#55 0x00000000004bed3d in PyEval_EvalFrameEx ()
#56 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#57 0x00000000004d55f3 in ?? ()
#58 0x00000000004a577e in PyObject_Call ()
#59 0x00000000004bed3d in PyEval_EvalFrameEx ()
#60 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#61 0x00000000004c1e6f in PyEval_EvalFrameEx ()
#62 0x00000000004c136f in PyEval_EvalFrameEx ()
#63 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#64 0x00000000004c1e6f in PyEval_EvalFrameEx ()
#65 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#66 0x00000000004c16e7 in PyEval_EvalFrameEx ()
#67 0x00000000004b9ab6 in PyEval_EvalCodeEx ()
#68 0x00000000004eb30f in ?? ()
#69 0x00000000004e5422 in PyRun_FileExFlags ()
#70 0x00000000004e3cd6 in PyRun_SimpleFileExFlags ()
#71 0x0000000000493ae2 in Py_Main ()
#72 0x00007ffff7810830 in __libc_start_main (main=0x4934c0 <main>, argc=6, argv=0x7fffffffdb88, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffdb78)
at ../csu/libc-start.c:291
#73 0x00000000004933e9 in _start ()