On 03/16/2011 01:55 PM, mark florisson wrote:
On 16 March 2011 13:37, Dag Sverre Seljebotn<d.s.seljeb...@astro.uio.no> wrote:
On 03/16/2011 12:54 PM, mark florisson wrote:
On 16 March 2011 11:58, Dag Sverre Seljebotn<d.s.seljeb...@astro.uio.no>
wrote:
On 03/16/2011 11:28 AM, mark florisson wrote:
I implemented the 'with gil:' statement, and have added error checking
for nested 'with gil' or 'with nogil' statements. For instance, with
the patch applied Cython wil issue an error when you have e.g.
with nogil:
with nogil:
...
(or the same thing for 'with gil:'). This because nested 'nogil' or
'gil' blocks, without intermediate GIL-acquiring/releasing, will abort
the Python interpreter. However, if people are acquiring the GIL
manually in nogil blocks and then want to release the GIL with a
'nogil' block, it will incorrectly issue an error. I do think this
kind of code is uncommon, but perhaps we want to issue a warning
instead?
I think we should make nested nogil-s noops, i.e.
with nogil:
with nogil: # => if True:
This is because one may want to change "with nogil" to "with gil" for
debugging purposes (allow printing debug information).
Interesting, that does sound convenient, but I'm not if mere
convenience should move us to simply ignore what is technically most
likely incorrect code (unless there is intermediate manual locking).
I'm not sure if I understand what you mean here. How does simply ignoring
redundant "with [no]gil" statements cause incorrect code? Or do you mean
this is a
I'm just trying to minimize the "language getting in your way" factor. It is
pretty useless to write
if x:
if x:
...
as well, but Python does allow it.
Warnings on nested "with nogil" is more the role of a "cylint" in my
opinion.
Perhaps you're right. However, I just think it is important for users
to realize that in general, they cannot unblock threads recursively.
Currently the error checking code catches multiple nested 'with
(no)gil', but it doesn't catch this:
cdef void func() nogil:
with nogil:
pass
with nogil:
func()
But the problem is that it does abort the interpreter. So I thought
that perhaps emphasizing that that code is incorrect for at least the
easy-to-catch cases, we might make users somewhat more aware. Because
if the above code aborts Python, but a nested 'with nogil:' is valid
code, there might be a source for confusion.
Ah, right. I guess I agree with disallowing nested "with nogil"
statements for the time being then.
Dag Sverre
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