python - IO错误 : close() called during concurrent operation on the same file object

Question

此错误的常见原因是什么？ (不看代码)

我用谷歌搜索过，但似乎没有找到任何关于此类错误的引用资料。

我最初的猜测是(通过查看错误消息)，有一个 thr/proc 正在对对象执行某些操作，而另一个 thr/proc 正试图关闭它。

文件对象是否有类似锁的机制？

Answer 1

文件-目标代码的某些部分允许多线程——它们发布GIL在操作期间，即 python-2.7.9/Objects/fileobject.c 中的 file_read() 包含以下行:

FILE_BEGIN_ALLOW_THREADS(f)
errno = 0;
chunksize = Py_UniversalNewlineFread(BUF(v) + bytesread,
            buffersize - bytesread, f->f_fp, (PyObject *)f);
interrupted = ferror(f->f_fp) && errno == EINTR;
FILE_END_ALLOW_THREADS(f)

FILE_BEGIN_ALLOW_THREADS 增加引用计数器，在 close() 端检查:

/*
* These macros release the GIL while preventing the f_close() function being
* called in the interval between them.  For that purpose, a running total of
* the number of currently running unlocked code sections is kept in
* the unlocked_count field of the PyFileObject. The close() method raises
* an IOError if that field is non-zero.  See issue #815646, #595601.
*/

#define FILE_BEGIN_ALLOW_THREADS(fobj) \
{ \
    fobj->unlocked_count++; \
    Py_BEGIN_ALLOW_THREADS

我试图用下面的脚本重现这种行为，但它使我的解释器出现段错误:

import sys
from threading import Thread

def read():
    sys.stdin.read(10)

t = Thread(target = read)
t.start()
sys.stdin.close()
t.join()

无论如何，您可以使用 threading 模块中的 Lock 对象:

import sys
from threading import Thread, Lock

stdin_lock = Lock()

def read():
    with stdin_lock:
        sys.stdin.read(10)

t = Thread(target = read)
t.start()
with stdin_lock:
    sys.stdin.close()
t.join()