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Re: [PATCH] Fix python-interactive with Python 3.6
On 2017-01-20 11:37, Pedro Alves wrote:
On 01/20/2017 03:15 PM, Simon Marchi wrote:
Since Python 3.4, the callback installed in
should return a value allocated with PyMem_RawMalloc instead of
PyMem_Malloc. The reason is that PyMem_Malloc must be called with the
Python Global Interpreter Lock (GIL) held, which is not the case in
context where this function is called. PyMem_RawMalloc was introduced
for cases like this.
+/* Starting from Python 3.4, the result of the
+ callback must be allocated with PyMem_RawMalloc rather than
+#if PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 4
This will break with PY_MAJOR_VERSION 4 (at some point :-) ).
Yeah, I thought about that and concluded it would be a problem for my
#if PY_MAJOR_VERSION > 3
|| (PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION >= 4)
Or add some macro that makes it a bit easier to write,
like "#if HAVE_PY_AT_LEAST(3, 4)" or
"#if GDB_PY_VERSION >= 3004" (like GCC_VERSION).
Or use Python's PY_VERSION_HEX, like
"#if PY_VERSION_HEX >= 0x03040000".
I think that's better.
+#define PyOS_ReadlineFunctionPointer_Malloc PyMem_RawMalloc
+#define PyOS_ReadlineFunctionPointer_Malloc PyMem_Malloc
It sounds like we'll find other cases that will need
to call PyMem_RawMalloc going forward? How about handling
this similarly to how we handle fixing up other missing
Python bits, in python-internal.h. Like:
For now it looks like this is the only place where the Python API
requires using PyMem_RawMalloc. In the other cases, we are holding the
GIL, thanks to gdbpy_enter, so using the regular PyMem functions is ok.
It doesn't mean there won't be other cases added in the future though...
#if python < 3.4
static inline void *
gdb_PyMem_RawMalloc (size_t n)
return gdb_PyMem_Malloc (n);
#define PyMem_RawMalloc(n) gdb_PyMem_RawMalloc (n)
... and this is cleaner anyway. But why not just
#if python < 3.4
#define PyMem_RawMalloc PyMem_Malloc
/* Readline function suitable for PyOS_ReadlineFunctionPointer, which
is used for Python's interactive parser and raw_input. In both
cases, sys_stdin and sys_stdout are always stdin and stdout
@@ -63,7 +73,7 @@ gdbpy_readline_wrapper (FILE *sys_stdin, FILE
/* Detect EOF (Ctrl-D). */
if (p == NULL)
- q = (char *) PyMem_Malloc (1);
+ q = (char *) PyOS_ReadlineFunctionPointer_Malloc (1);
and then write PyMem_RawMalloc here.