用C和mod_wsgi在Apache中扩展Python/Django

Question

我有一个关于用C代码扩展Python和mod_wsgi的问题。

我在一个Apache服务器上有一个Django应用，它会查询PostgreSQL数据库来生成报告。在某些报告中，系统会生成一个包含结果的CSV文件。为了创建这个CSV文件，有时候系统需要用Python处理超过二十万个记录，这显然非常慢。为了加快这个过程，我们编写了一个C模块来完成这项工作，这样速度提高了很多倍。我们尝试过使用ctypes和创建一个C的Python模块，这两种方法在运行服务器时都能正常工作，但在Apache和mod_wsgi下执行时却崩溃了。

在httpd-error.log中的错误信息是：

[Wed Jul 27 02:33:52 2011] [notice] child pid 44657 exit signal Segmentation fault (11)

有没有什么建议？

代码是：

# Creates the HttpResponse object with the appropriate CSV header.
response = HttpResponse(mimetype='application/x-zip-compressed')
response['Content-Disposition'] = \
    'attachment; filename=' + filename + '.zip'

p0 = 'descarga_' + str(datetime.today()) + '.csv'

p1 = settings.DATABASES['default']['NAME']
p2 = settings.DATABASES['default']['USER']

#lib.generar(string_at(p0),p1,p2,string_at(str(init)),string_at(str(end)),string_at(str(provider)))

import generador
generador.generar(p0,p1,p2,str(init),str(end),str(provider))

在我们调用generador.generar()这个外部C模块时，它就崩溃了。

我还尝试过使用GDb，正如@GrahamDumpleton建议的那样，输出结果并不是很有用 :(

调试器启动后，当我点击执行调用C模块的链接时，又一次出现了段错误。

(gdb) run -X
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /usr/local/sbin/httpd -X
[New LWP 101064]
[New Thread 28501140 (LWP 101064)]


Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 28501140 (LWP 101064)]
0x2847d423 in fwrite () from /lib/libc.so.7

在段错误之后，我在调试器中尝试了'where'命令，这就是它给出的结果：

(gdb) where
#0  0x2847d423 in fwrite () from /lib/libc.so.7
#1  0x293f8d09 in generar () from /ruta/al/codigo/generador.so
#2  0x28912caa in PyCFunction_Call () from /usr/local/lib/libpython2.7.so
#3  0x2896e49a in PyEval_EvalFrameEx () from /usr/local/lib/libpython2.7.so
#4  0x2897044b in PyEval_EvalCodeEx () from /usr/local/lib/libpython2.7.so
#5  0x288feafd in PyClassMethod_New () from /usr/local/lib/libpython2.7.so
#6  0x288d622c in PyObject_Call () from /usr/local/lib/libpython2.7.so
#7  0x2896c27a in PyEval_EvalFrameEx () from /usr/local/lib/libpython2.7.so
#8  0x2896fadc in PyEval_EvalFrameEx () from /usr/local/lib/libpython2.7.so
#9  0x2897044b in PyEval_EvalCodeEx () from /usr/local/lib/libpython2.7.so
#10 0x288fea0a in PyClassMethod_New () from /usr/local/lib/libpython2.7.so
#11 0x288d622c in PyObject_Call () from /usr/local/lib/libpython2.7.so
#12 0x288e4fd8 in PyClass_IsSubclass () from /usr/local/lib/libpython2.7.so
#13 0x288d622c in PyObject_Call () from /usr/local/lib/libpython2.7.so
#14 0x2893044c in _PyObject_LookupSpecial () from /usr/local/lib/libpython2.7.so
#15 0x288d622c in PyObject_Call () from /usr/local/lib/libpython2.7.so
#16 0x28968ec4 in PyEval_CallObjectWithKeywords () from /usr/local/lib/libpython2.7.so
#17 0x2889b229 in Adapter_run (self=0x28b4dd58, object=0x28c7d50c) at mod_wsgi.c:3841
#18 0x2889be50 in wsgi_execute_script (r=0x28cb4058) at mod_wsgi.c:6547
#19 0x2889de66 in wsgi_hook_handler (r=0x28cb4058) at mod_wsgi.c:9080
#20 0x08076b19 in ap_run_handler (r=0x28cb4058) at config.c:157
#21 0x08079dee in ap_invoke_handler (r=0x28cb4058) at config.c:376
#22 0x08084eb0 in ap_process_request (r=0x28cb4058) at http_request.c:282
#23 0x0808201b in ap_process_http_connection (c=0x28b201f0) at http_core.c:190
#24 0x0807de09 in ap_run_process_connection (c=0x28b201f0) at connection.c:43
#25 0x08089791 in child_main (child_num_arg=Variable "child_num_arg" is not available.
) at prefork.c:662
#26 0x080899e3 in make_child (s=0x28510f10, slot=0) at prefork.c:707
#27 0x0808a591 in ap_mpm_run (_pconf=0x2850f018, plog=0x2853d018, s=0x28510f10) at  prefork.c:983
#28 0x08064195 in main (argc=676384792, argv=0x28b1e018) at main.c:739

django apache mod_wsgi postgresql c# csv performance optimization segmentation fault

用C和mod_wsgi在Apache中扩展Python/Django

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