使用open() IOError循环

Question

我正在迭代几个DB记录，并将数据从它们各自的BLOB字段写入文件中：

def build(self, records):
    """
    Builds openimmo.anhang
    """
    result = None
    anh_records = [r for r in records if type(r) == anhaenge]
    if not anh_records:
        return result
    anhang = []
    print('RECORDS: ' + str(len(anh_records)))
    for anh_record in anh_records:
        if anh_record.daten:
            __, path = mkstemp()
            with open(path, 'wb') as target:
                target.write(anh_record.daten)
            anh = openimmo.anhang()
            anh.anhangtitel = anh_record.anhangtitel
            anh.format = 'image/jpeg' #MIMEUtil.getmime(path)
            anh.daten = openimmo.daten()
            anh.daten.pfad = path
            anh.location = id2location.get(anh_record.location)
            anh.gruppe = id2gruppe.get(anh_record.gruppe)
            anhang.append(anh)
    try:
        result.validateBinding()
    except:
        self.log.err('Could not build "anhang": ' + str(result))
    if anhang:
        result = openimmo.anhaenge()
        result.anhang = anhang
    return result

然而，这会产生以下错误：

RECORDS: 5
Message: "[Errno 24] Too many open files: '/tmp/tmpo54qfq'
daemon panic:
Caught unexpected exception in _main() on 2014-08-20 11:53:37.918353
Message: "[Errno 24] Too many open files: '/tmp/tmpo54qfq'" of type "<class 'IOError'>"
Traceback (most recent call last):
  File "/usr/local/lib/python3.2/dist-packages/homie_core-1.0-py3.2.egg/homie/serv/daemon.py", line 345, in __run
  File "/usr/local/lib/python3.2/dist-packages/homie_core-1.0-py3.2.egg/homie/serv/service.py", line 72, in _main
  File "/usr/local/lib/python3.2/dist-packages/homie_core-1.0-py3.2.egg/homie/api/itf.py", line 127, in export
  File "/usr/local/lib/python3.2/dist-packages/homie_openimmodb-0.2_indev-py3.2.egg/openimmodb/itf.py", line 51, in _retrieve
  File "/usr/local/lib/python3.2/dist-packages/homie_openimmodb-0.2_indev-py3.2.egg/openimmodb/conv.py", line 27, in decode
  File "/usr/local/lib/python3.2/dist-packages/homie_openimmodb-0.2_indev-py3.2.egg/openimmodb/factories/openimmo/immobilie.py", line 60, in build
  File "/usr/local/lib/python3.2/dist-packages/homie_openimmodb-0.2_indev-py3.2.egg/openimmodb/factories/openimmo/anhaenge.py", line 30, in build
IOError: [Errno 24] Too many open files: '/tmp/tmpo54qfq'

根据lsof的说法，整个过程有超过5k个打开的文件：

# lsof| grep python3| wc -l
5375

我检查了几次:当我打开一个文件时，我在代码中的任何地方都使用with open(file) as desc。不应该在每个with块的末尾自动关闭文件，还是我遗漏了什么？

Answer 1

tempfile.mkstemp()为您打开一个文件：

fd, path = mkstemp()
with open(fd, 'wb') as target:
    # os.close(fd) is called automatically

您不需要打开另一个文件的open(path) (同名)。

您可以使用tempfile.NamedTemporaryFile(delete=False)而不是tempfile.mkstemp()。