David-Sarah Hopwood <david-sa...@jacaranda.org> added the comment: If I understand the bug in the Windows console functions correctly, a limit of 32767 bytes might not always be small enough. The problem is that if two or more threads are concurrently using any console functions (which all use the same 64 KiB heap), they could try to allocate up to 32767 bytes plus overhead at the same time, which will fail.
I wasn't able to provoke this by writing to sys.stdout.buffer (maybe there is locking that prevents concurrent writes), but the following code that calls WriteFile directly, does provoke it. GetLastError() returns 8 (ERROR_NOT_ENOUGH_MEMORY; see http://msdn.microsoft.com/en-us/library/ms681382%28v=vs.85%29.aspx), indicating that it's the same bug. # Warning: this test may DoS your system. from threading import Thread import sys from ctypes import WINFUNCTYPE, windll, POINTER, byref, c_int from ctypes.wintypes import BOOL, HANDLE, DWORD, LPVOID, LPCVOID GetStdHandle = WINFUNCTYPE(HANDLE, DWORD)(("GetStdHandle", windll.kernel32)) WriteFile = WINFUNCTYPE(BOOL, HANDLE, LPCVOID, DWORD, POINTER(DWORD), LPVOID) \ (("WriteFile", windll.kernel32)) GetLastError = WINFUNCTYPE(DWORD)(("GetLastError", windll.kernel32)) STD_OUTPUT_HANDLE = DWORD(-11) INVALID_HANDLE_VALUE = DWORD(-1).value hStdout = GetStdHandle(STD_OUTPUT_HANDLE) assert hStdout is not None and hStdout != INVALID_HANDLE_VALUE L = 32760 data = b'a'*L def run(): n = DWORD(0) while True: ret = WriteFile(hStdout, data, L, byref(n), None) if ret == 0 or n.value != L: print(ret, n.value, GetLastError()) sys.exit(1) [Thread(target=run).start() for i in range(10)] ---------- nosy: +davidsarah _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue11395> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
