diff --git a/Doc/c-api/file.rst b/Doc/c-api/file.rst
index 1bb5b22..e107268 100644
--- a/Doc/c-api/file.rst
+++ b/Doc/c-api/file.rst
@@ -58,10 +58,42 @@
    closed.  Return *NULL* on failure.
 
 
-.. cfunction:: FILE* PyFile_AsFile(PyObject *p)
+.. cfunction:: FILE* PyFile_AsFile(PyObject \*p)
 
    Return the file object associated with *p* as a :ctype:`FILE\*`.
 
+   If the caller will ever use the returned :ctype:`FILE\*` object while
+   the GIL is released it must also call the `PyFile_IncUseCount` and
+   `PyFile_DecUseCount` functions described below as appropriate.
+
+
+.. cfunction:: void PyFile_IncUseCount(PyFileObject \*p)
+
+   Increments the PyFileObject's internal use count to indicate
+   that the underlying :ctype:`FILE\*` is being used.
+   This prevents Python from calling f_close() on it from another thread.
+   Callers of this must call `PyFile_DecUseCount` when they are
+   finished with the :ctype:`FILE\*`.  Otherwise the file object will
+   never be closed by Python.
+
+   The GIL must be held while calling this function.
+
+   The suggested use is to call this after `PyFile_AsFile` just before
+   you release the GIL.
+
+   .. versionadded:: 2.6
+
+
+.. cfunction:: void PyFile_DecUseCount(PyFileObject \*p)
+
+   Decrements the PyFileObject's internal unlocked_count member to
+   indicate that the caller is done with its own use of the :ctype:`FILE\*`.
+   This may only be called to undo a prior call to `PyFile_IncUseCount`.
+
+   The GIL must be held while calling this function.
+
+   .. versionadded:: 2.6
+
 
 .. cfunction:: PyObject* PyFile_GetLine(PyObject *p, int n)
 
diff --git a/Include/fileobject.h b/Include/fileobject.h
index 75b0f03..56fae81 100644
--- a/Include/fileobject.h
+++ b/Include/fileobject.h
@@ -25,6 +25,8 @@
 	int f_skipnextlf;	/* Skip next \n */
 	PyObject *f_encoding;
 	PyObject *weakreflist; /* List of weak references */
+	int unlocked_count;	/* Num. currently running sections of code
+				   using f_fp with the GIL released. */
 } PyFileObject;
 
 PyAPI_DATA(PyTypeObject) PyFile_Type;
@@ -38,6 +40,8 @@
 PyAPI_FUNC(PyObject *) PyFile_FromFile(FILE *, char *, char *,
                                              int (*)(FILE *));
 PyAPI_FUNC(FILE *) PyFile_AsFile(PyObject *);
+PyAPI_FUNC(void) PyFile_IncUseCount(PyFileObject *);
+PyAPI_FUNC(void) PyFile_DecUseCount(PyFileObject *);
 PyAPI_FUNC(PyObject *) PyFile_Name(PyObject *);
 PyAPI_FUNC(PyObject *) PyFile_GetLine(PyObject *, int);
 PyAPI_FUNC(int) PyFile_WriteObject(PyObject *, PyObject *, int);
diff --git a/Lib/test/test_file.py b/Lib/test/test_file.py
index 3ae460c..aab3e70 100644
--- a/Lib/test/test_file.py
+++ b/Lib/test/test_file.py
@@ -1,9 +1,13 @@
 import sys
 import os
 import unittest
+import itertools
+import time
+import threading
 from array import array
 from weakref import proxy
 
+from test import test_support
 from test.test_support import TESTFN, findfile, run_unittest
 from UserList import UserList
 
@@ -339,11 +343,173 @@
         self.failUnless(f.subclass_closed)
 
 
+class FileThreadingTests(unittest.TestCase):
+    # These tests check the ability to call various methods of file objects
+    # (including close()) concurrently without crashing the Python interpreter.
+    # See #815646, #595601
+
+    def setUp(self):
+        self.f = None
+        self.filename = TESTFN
+        with open(self.filename, "w") as f:
+            f.write("\n".join("0123456789"))
+        self._count_lock = threading.Lock()
+        self.close_count = 0
+        self.close_success_count = 0
+
+    def tearDown(self):
+        if self.f:
+            try:
+                self.f.close()
+            except (EnvironmentError, ValueError):
+                pass
+        try:
+            os.remove(self.filename)
+        except EnvironmentError:
+            pass
+
+    def _create_file(self):
+        self.f = open(self.filename, "w+")
+
+    def _close_file(self):
+        with self._count_lock:
+            self.close_count += 1
+        self.f.close()
+        with self._count_lock:
+            self.close_success_count += 1
+
+    def _close_and_reopen_file(self):
+        self._close_file()
+        # if close raises an exception thats fine, self.f remains valid so
+        # we don't need to reopen.
+        self._create_file()
+
+    def _run_workers(self, func, nb_workers, duration=0.2):
+        with self._count_lock:
+            self.close_count = 0
+            self.close_success_count = 0
+        self.do_continue = True
+        threads = []
+        try:
+            for i in range(nb_workers):
+                t = threading.Thread(target=func)
+                t.start()
+                threads.append(t)
+            for _ in xrange(100):
+                time.sleep(duration/100)
+                with self._count_lock:
+                    if self.close_count-self.close_success_count > nb_workers+1:
+                        if test_support.verbose:
+                            print 'Q',
+                        break
+            time.sleep(duration)
+        finally:
+            self.do_continue = False
+            for t in threads:
+                t.join()
+
+    def _test_close_open_io(self, io_func, nb_workers=5):
+        def worker():
+            self._create_file()
+            funcs = itertools.cycle((
+                lambda: io_func(),
+                lambda: self._close_and_reopen_file(),
+            ))
+            for f in funcs:
+                if not self.do_continue:
+                    break
+                try:
+                    f()
+                except (IOError, ValueError):
+                    pass
+        self._run_workers(worker, nb_workers)
+        if test_support.verbose:
+            # Useful verbose statistics when tuning this test to take
+            # less time to run but still ensuring that its still useful.
+            #
+            # the percent of close calls that raised an error
+            percent = 100. - 100.*self.close_success_count/self.close_count
+            print self.close_count, ('%.4f ' % percent),
+
+    def test_close_open(self):
+        def io_func():
+            pass
+        self._test_close_open_io(io_func)
+
+    def test_close_open_flush(self):
+        def io_func():
+            self.f.flush()
+        self._test_close_open_io(io_func)
+
+    def test_close_open_iter(self):
+        def io_func():
+            list(iter(self.f))
+        self._test_close_open_io(io_func)
+
+    def test_close_open_isatty(self):
+        def io_func():
+            self.f.isatty()
+        self._test_close_open_io(io_func)
+
+    def test_close_open_print(self):
+        def io_func():
+            print >> self.f, ''
+        self._test_close_open_io(io_func)
+
+    def test_close_open_read(self):
+        def io_func():
+            self.f.read(0)
+        self._test_close_open_io(io_func)
+
+    def test_close_open_readinto(self):
+        def io_func():
+            a = array('c', 'xxxxx')
+            self.f.readinto(a)
+        self._test_close_open_io(io_func)
+
+    def test_close_open_readline(self):
+        def io_func():
+            self.f.readline()
+        self._test_close_open_io(io_func)
+
+    def test_close_open_readlines(self):
+        def io_func():
+            self.f.readlines()
+        self._test_close_open_io(io_func)
+
+    def test_close_open_seek(self):
+        def io_func():
+            self.f.seek(0, 0)
+        self._test_close_open_io(io_func)
+
+    def test_close_open_tell(self):
+        def io_func():
+            self.f.tell()
+        self._test_close_open_io(io_func)
+
+    def test_close_open_truncate(self):
+        def io_func():
+            self.f.truncate()
+        self._test_close_open_io(io_func)
+
+    def test_close_open_write(self):
+        def io_func():
+            self.f.write('')
+        self._test_close_open_io(io_func)
+
+    def test_close_open_writelines(self):
+        def io_func():
+            self.f.writelines('')
+        self._test_close_open_io(io_func)
+
+
+
 def test_main():
     # Historically, these tests have been sloppy about removing TESTFN.
     # So get rid of it no matter what.
     try:
-        run_unittest(AutoFileTests, OtherFileTests, FileSubclassTests)
+        run_unittest(AutoFileTests, OtherFileTests, FileSubclassTests,
+            FileThreadingTests)
     finally:
         if os.path.exists(TESTFN):
             os.unlink(TESTFN)
diff --git a/Misc/NEWS b/Misc/NEWS
index 2e160f5..a87d3e0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -18,6 +18,11 @@
 Library
 -------
 
+- Issue #815646: Individual file objects may now be used from multiple
+  threads at once without fear of crashing the Python interpreter.  If
+  file.close() is called while an object is in use by another thread
+  an IOError exception will be raised and the file will not be closed.
+
 - The bundled libffi copy is now in sync with the recently released
   libffi3.0.5 version, apart from some small changes to
   Modules/_ctypes/libffi/configure.ac.
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 0a6ccff..d61e6a0 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -48,6 +48,30 @@
 #define NEWLINE_LF 2		/* \n newline seen */
 #define NEWLINE_CRLF 4		/* \r\n newline seen */
 
+/*
+ * 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
+
+#define FILE_END_ALLOW_THREADS(fobj) \
+	Py_END_ALLOW_THREADS \
+	fobj->unlocked_count--; \
+	assert(fobj->unlocked_count >= 0); \
+}
+
+#define FILE_ABORT_ALLOW_THREADS(fobj) \
+	Py_BLOCK_THREADS \
+	fobj->unlocked_count--; \
+	assert(fobj->unlocked_count >= 0);
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -61,6 +85,17 @@
 		return ((PyFileObject *)f)->f_fp;
 }
 
+void PyFile_IncUseCount(PyFileObject *fobj)
+{
+	fobj->unlocked_count++;
+}
+
+void PyFile_DecUseCount(PyFileObject *fobj)
+{
+	fobj->unlocked_count--;
+	assert(fobj->unlocked_count >= 0);
+}
+
 PyObject *
 PyFile_Name(PyObject *f)
 {
@@ -70,6 +105,19 @@
 		return ((PyFileObject *)f)->f_name;
 }
 
+/* This is a safe wrapper around PyObject_Print to print to the FILE
+   of a PyFileObject. PyObject_Print releases the GIL but knows nothing
+   about PyFileObject. */
+static int
+file_PyObject_Print(PyObject *op, PyFileObject *f, int flags)
+{
+	int result;
+	PyFile_IncUseCount(f);
+	result = PyObject_Print(op, f->f_fp, flags);
+	PyFile_DecUseCount(f);
+	return result;
+}
+
 /* On Unix, fopen will succeed for directories.
    In Python, there should be no file objects referring to
    directories, so we need a check.  */
@@ -220,20 +268,20 @@
 		PyObject *wmode;
 		wmode = PyUnicode_DecodeASCII(newmode, strlen(newmode), NULL);
 		if (f->f_name && wmode) {
-			Py_BEGIN_ALLOW_THREADS
+			FILE_BEGIN_ALLOW_THREADS(f)
 			/* PyUnicode_AS_UNICODE OK without thread
 			   lock as it is a simple dereference. */
 			f->f_fp = _wfopen(PyUnicode_AS_UNICODE(f->f_name),
 					  PyUnicode_AS_UNICODE(wmode));
-			Py_END_ALLOW_THREADS
+			FILE_END_ALLOW_THREADS(f)
 		}
 		Py_XDECREF(wmode);
 	}
 #endif
 	if (NULL == f->f_fp && NULL != name) {
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		f->f_fp = fopen(name, newmode);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 	}
 
 	if (f->f_fp == NULL) {
@@ -271,6 +319,48 @@
 	return (PyObject *)f;
 }
 
+static PyObject *
+close_the_file(PyFileObject *f)
+{
+	int sts = 0;
+	int (*local_close)(FILE *);
+	FILE *local_fp = f->f_fp;
+	if (local_fp != NULL) {
+		local_close = f->f_close;
+		if (local_close != NULL && f->unlocked_count > 0) {
+			if (f->ob_refcnt > 0) {
+				PyErr_SetString(PyExc_IOError,
+					"close() called during concurrent "
+					"operation on the same file object.");
+			} else {
+				/* This should not happen unless someone is
+				 * carelessly playing with the PyFileObject
+				 * struct fields and/or its associated FILE
+				 * pointer. */
+				PyErr_SetString(PyExc_SystemError,
+					"PyFileObject locking error in "
+					"destructor (refcnt <= 0 at close).");
+			}
+			return NULL;
+		}
+		/* NULL out the FILE pointer before releasing the GIL, because
+		 * it will not be valid anymore after the close() function is
+		 * called. */
+		f->f_fp = NULL;
+		if (local_close != NULL) {
+			Py_BEGIN_ALLOW_THREADS
+			errno = 0;
+			sts = (*local_close)(local_fp);
+			Py_END_ALLOW_THREADS
+			if (sts == EOF)
+				return PyErr_SetFromErrno(PyExc_IOError);
+			if (sts != 0)
+				return PyInt_FromLong((long)sts);
+		}
+	}
+	Py_RETURN_NONE;
+}
+
 PyObject *
 PyFile_FromFile(FILE *fp, char *name, char *mode, int (*close)(FILE *))
 {
@@ -386,15 +476,16 @@
 static void
 file_dealloc(PyFileObject *f)
 {
-	int sts = 0;
+	PyObject *ret;
 	if (f->weakreflist != NULL)
 		PyObject_ClearWeakRefs((PyObject *) f);
-	if (f->f_fp != NULL && f->f_close != NULL) {
-		Py_BEGIN_ALLOW_THREADS
-		sts = (*f->f_close)(f->f_fp);
-		Py_END_ALLOW_THREADS
-		if (sts == EOF) 
-			PySys_WriteStderr("close failed: [Errno %d] %s\n", errno, strerror(errno)); 
+	ret = close_the_file(f);
+	if (!ret) {
+		PySys_WriteStderr("close failed in file object destructor:\n");
+		PyErr_Print();
+	}
+	else {
+		Py_DECREF(ret);
 	}
 	PyMem_Free(f->f_setbuf);
 	Py_XDECREF(f->f_name);
@@ -432,24 +523,10 @@
 static PyObject *
 file_close(PyFileObject *f)
 {
-	int sts = 0;
-	if (f->f_fp != NULL) {
-		if (f->f_close != NULL) {
-			Py_BEGIN_ALLOW_THREADS
-			errno = 0;
-			sts = (*f->f_close)(f->f_fp);
-			Py_END_ALLOW_THREADS
-		}
-		f->f_fp = NULL;
-	}
+	PyObject *sts = close_the_file(f);
 	PyMem_Free(f->f_setbuf);
 	f->f_setbuf = NULL;
-	if (sts == EOF)
-		return PyErr_SetFromErrno(PyExc_IOError);
-	if (sts != 0)
-		return PyInt_FromLong((long)sts);
-	Py_INCREF(Py_None);
-	return Py_None;
+	return sts;
 }
 
 
@@ -566,10 +643,10 @@
 	if (PyErr_Occurred())
 		return NULL;
 
-	Py_BEGIN_ALLOW_THREADS
+ 	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	ret = _portable_fseek(f->f_fp, offset, whence);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 
 	if (ret != 0) {
 		PyErr_SetFromErrno(PyExc_IOError);
@@ -603,10 +680,10 @@
 	 * then at least on Windows).  The easiest thing is to capture
 	 * current pos now and seek back to it at the end.
 	 */
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	initialpos = _portable_ftell(f->f_fp);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (initialpos == -1)
 		goto onioerror;
 
@@ -631,10 +708,10 @@
 	 * I/O, and a flush may be necessary to synch both platform views
 	 * of the current file state.
 	 */
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	ret = fflush(f->f_fp);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (ret != 0)
 		goto onioerror;
 
@@ -645,15 +722,15 @@
 		HANDLE hFile;
 
 		/* Have to move current pos to desired endpoint on Windows. */
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		errno = 0;
 		ret = _portable_fseek(f->f_fp, newsize, SEEK_SET) != 0;
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 		if (ret)
 			goto onioerror;
 
 		/* Truncate.  Note that this may grow the file! */
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		errno = 0;
 		hFile = (HANDLE)_get_osfhandle(fileno(f->f_fp));
 		ret = hFile == (HANDLE)-1;
@@ -662,24 +739,24 @@
 			if (ret)
 				errno = EACCES;
 		}
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 		if (ret)
 			goto onioerror;
 	}
 #else
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	ret = ftruncate(fileno(f->f_fp), newsize);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (ret != 0)
 		goto onioerror;
 #endif /* !MS_WINDOWS */
 
 	/* Restore original file position. */
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	ret = _portable_fseek(f->f_fp, initialpos, SEEK_SET) != 0;
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (ret)
 		goto onioerror;
 
@@ -700,10 +777,11 @@
 
 	if (f->f_fp == NULL)
 		return err_closed();
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	pos = _portable_ftell(f->f_fp);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
+
 	if (pos == -1) {
 		PyErr_SetFromErrno(PyExc_IOError);
 		clearerr(f->f_fp);
@@ -740,10 +818,10 @@
 
 	if (f->f_fp == NULL)
 		return err_closed();
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	res = fflush(f->f_fp);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (res != 0) {
 		PyErr_SetFromErrno(PyExc_IOError);
 		clearerr(f->f_fp);
@@ -759,9 +837,9 @@
 	long res;
 	if (f->f_fp == NULL)
 		return err_closed();
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	res = isatty((int)fileno(f->f_fp));
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	return PyBool_FromLong(res);
 }
 
@@ -861,11 +939,11 @@
 		return NULL;
 	bytesread = 0;
 	for (;;) {
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		errno = 0;
 		chunksize = Py_UniversalNewlineFread(BUF(v) + bytesread,
 			  buffersize - bytesread, f->f_fp, (PyObject *)f);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 		if (chunksize == 0) {
 			if (!ferror(f->f_fp))
 				break;
@@ -917,11 +995,11 @@
 		return NULL;
 	ndone = 0;
 	while (ntodo > 0) {
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		errno = 0;
 		nnow = Py_UniversalNewlineFread(ptr+ndone, ntodo, f->f_fp,
 						(PyObject *)f);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 		if (nnow == 0) {
 			if (!ferror(f->f_fp))
 				break;
@@ -986,7 +1064,7 @@
 
 #ifdef USE_FGETS_IN_GETLINE
 static PyObject*
-getline_via_fgets(FILE *fp)
+getline_via_fgets(PyFileObject *f, FILE *fp)
 {
 /* INITBUFSIZE is the maximum line length that lets us get away with the fast
  * no-realloc, one-fgets()-call path.  Boosting it isn't free, because we have
@@ -1019,13 +1097,13 @@
 	total_v_size = INITBUFSIZE;	/* start small and pray */
 	pvfree = buf;
 	for (;;) {
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		pvend = buf + total_v_size;
 		nfree = pvend - pvfree;
 		memset(pvfree, '\n', nfree);
 		assert(nfree < INT_MAX); /* Should be atmost MAXBUFSIZE */
 		p = fgets(pvfree, (int)nfree, fp);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 
 		if (p == NULL) {
 			clearerr(fp);
@@ -1094,13 +1172,13 @@
 	 * the code above for detailed comments about the logic.
 	 */
 	for (;;) {
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		pvend = BUF(v) + total_v_size;
 		nfree = pvend - pvfree;
 		memset(pvfree, '\n', nfree);
 		assert(nfree < INT_MAX);
 		p = fgets(pvfree, (int)nfree, fp);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 
 		if (p == NULL) {
 			clearerr(fp);
@@ -1171,7 +1249,7 @@
 
 #if defined(USE_FGETS_IN_GETLINE)
 	if (n <= 0 && !univ_newline )
-		return getline_via_fgets(fp);
+		return getline_via_fgets(f, fp);
 #endif
 	total_v_size = n > 0 ? n : 100;
 	v = PyString_FromStringAndSize((char *)NULL, total_v_size);
@@ -1181,7 +1259,7 @@
 	end = buf + total_v_size;
 
 	for (;;) {
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(f)
 		FLOCKFILE(fp);
 		if (univ_newline) {
 			c = 'x'; /* Shut up gcc warning */
@@ -1216,7 +1294,7 @@
 			buf != end)
 			;
 		FUNLOCKFILE(fp);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 		f->f_newlinetypes = newlinetypes;
 		f->f_skipnextlf = skipnextlf;
 		if (c == '\n')
@@ -1381,7 +1459,7 @@
 file_readlines(PyFileObject *f, PyObject *args)
 {
 	long sizehint = 0;
-	PyObject *list;
+	PyObject *list = NULL;
 	PyObject *line;
 	char small_buffer[SMALLCHUNK];
 	char *buffer = small_buffer;
@@ -1409,11 +1487,11 @@
 		if (shortread)
 			nread = 0;
 		else {
-			Py_BEGIN_ALLOW_THREADS
+			FILE_BEGIN_ALLOW_THREADS(f)
 			errno = 0;
 			nread = Py_UniversalNewlineFread(buffer+nfilled,
 				buffersize-nfilled, f->f_fp, (PyObject *)f);
-			Py_END_ALLOW_THREADS
+			FILE_END_ALLOW_THREADS(f)
 			shortread = (nread < buffersize-nfilled);
 		}
 		if (nread == 0) {
@@ -1422,10 +1500,7 @@
 				break;
 			PyErr_SetFromErrno(PyExc_IOError);
 			clearerr(f->f_fp);
-		  error:
-			Py_DECREF(list);
-			list = NULL;
-			goto cleanup;
+			goto error;
 		}
 		totalread += nread;
 		p = (char *)memchr(buffer+nfilled, '\n', nread);
@@ -1499,9 +1574,14 @@
 		if (err != 0)
 			goto error;
 	}
-  cleanup:
+
+cleanup:
 	Py_XDECREF(big_buffer);
 	return list;
+
+error:
+	Py_CLEAR(list);
+	goto cleanup;
 }
 
 static PyObject *
@@ -1514,10 +1594,10 @@
 	if (!PyArg_ParseTuple(args, f->f_binary ? "s#" : "t#", &s, &n))
 		return NULL;
 	f->f_softspace = 0;
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	n2 = fwrite(s, 1, n, f->f_fp);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (n2 != n) {
 		PyErr_SetFromErrno(PyExc_IOError);
 		clearerr(f->f_fp);
@@ -1615,8 +1695,8 @@
 
 		/* Since we are releasing the global lock, the
 		   following code may *not* execute Python code. */
-		Py_BEGIN_ALLOW_THREADS
 		f->f_softspace = 0;
+		FILE_BEGIN_ALLOW_THREADS(f)
 		errno = 0;
 		for (i = 0; i < j; i++) {
 		    	line = PyList_GET_ITEM(list, i);
@@ -1624,13 +1704,13 @@
 			nwritten = fwrite(PyString_AS_STRING(line),
 					  1, len, f->f_fp);
 			if (nwritten != len) {
-				Py_BLOCK_THREADS
+				FILE_ABORT_ALLOW_THREADS(f)
 				PyErr_SetFromErrno(PyExc_IOError);
 				clearerr(f->f_fp);
 				goto error;
 			}
 		}
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(f)
 
 		if (j < CHUNKSIZE)
 			break;
@@ -1895,11 +1975,11 @@
 		PyErr_NoMemory();
 		return -1;
 	}
-	Py_BEGIN_ALLOW_THREADS
+	FILE_BEGIN_ALLOW_THREADS(f)
 	errno = 0;
 	chunksize = Py_UniversalNewlineFread(
 		f->f_buf, bufsize, f->f_fp, (PyObject *)f);
-	Py_END_ALLOW_THREADS
+	FILE_END_ALLOW_THREADS(f)
 	if (chunksize == 0) {
 		if (ferror(f->f_fp)) {
 			PyErr_SetFromErrno(PyExc_IOError);
@@ -2008,6 +2088,7 @@
 		Py_INCREF(Py_None);
 		((PyFileObject *)self)->f_encoding = Py_None;
 		((PyFileObject *)self)->weakreflist = NULL;
+		((PyFileObject *)self)->unlocked_count = 0;
 	}
 	return self;
 }
@@ -2195,12 +2276,12 @@
 		return -1;
 	}
 	else if (PyFile_Check(f)) {
-		FILE *fp = PyFile_AsFile(f);
+		PyFileObject *fobj = (PyFileObject *) f;
 #ifdef Py_USING_UNICODE
-		PyObject *enc = ((PyFileObject*)f)->f_encoding;
+		PyObject *enc = fobj->f_encoding;
 		int result;
 #endif
-		if (fp == NULL) {
+		if (fobj->f_fp == NULL) {
 			err_closed();
 			return -1;
 		}
@@ -2215,11 +2296,11 @@
 			value = v;
 			Py_INCREF(value);
 		}
-		result = PyObject_Print(value, fp, flags);
+		result = file_PyObject_Print(value, fobj, flags);
 		Py_DECREF(value);
 		return result;
 #else
-		return PyObject_Print(v, fp, flags);
+		return file_PyObject_Print(v, fobj, flags);
 #endif
 	}
 	writer = PyObject_GetAttrString(f, "write");
@@ -2257,6 +2338,7 @@
 int
 PyFile_WriteString(const char *s, PyObject *f)
 {
+
 	if (f == NULL) {
 		/* Should be caused by a pre-existing error */
 		if (!PyErr_Occurred())
@@ -2265,14 +2347,15 @@
 		return -1;
 	}
 	else if (PyFile_Check(f)) {
+		PyFileObject *fobj = (PyFileObject *) f;
 		FILE *fp = PyFile_AsFile(f);
 		if (fp == NULL) {
 			err_closed();
 			return -1;
 		}
-		Py_BEGIN_ALLOW_THREADS
+		FILE_BEGIN_ALLOW_THREADS(fobj)
 		fputs(s, fp);
-		Py_END_ALLOW_THREADS
+		FILE_END_ALLOW_THREADS(fobj)
 		return 0;
 	}
 	else if (!PyErr_Occurred()) {