Looks like a problem in mkl's same_shape
the pointer to mkldnn::memory::desc &desc looks invalid.
(More stack frames follow...)
(gdb) p desc
$1 = (const mkldnn::memory::desc &) @0x10: <error reading variable>
(gdb) p dtype
$2 = 0
(gdb) p shape
$3 = (const mxnet::TShape &) @0x7f3905a58b50: {<nnvm::Tuple<long>> =
{static kStackCache = <optimized out>, ndim_ = 2, num_heap_allocated_ = 0,
data_stack_ = {20, 1, 139878025134112, 28}, data_heap_ = 0x0}, <No data
fields>}
(gdb)
On Thu, May 3, 2018 at 4:36 PM, Zheng, Da <dzz...@amazon.com> wrote:
> There are a few problems with valgrind, which makes it not an ideal tool
> for mxnet with python interface.
>
> First, valgrind generates a huge number of irrelevant messages, most of
> them from in Python itself.
>
> Second, valgrind can't emulate all CPU instructions. I remember that when
> I run valgrind with mxnet, valgrind exits with a strange error. I later on
> found that it was caused by an unsupported CPU instructions.
>
> Third, valgrind doesn't support multithreading well. As far as I know,
> valgrind runs everything in a single thread even if the program uses
> multi-threading. An error like this, which is likely caused by race
> condition, can't be caught by valgrind.
>
> I used to use Address Sanitizer for memory errors. This tool is much
> faster and can work with multi-threads. However, it doesn't work with
> Python for some reason.
>
> One thing we potentially can do is to use memory checker for C++ unit
> tests. Not sure it'll cover all memory errors we want.
>
> Best,
> Da
>
> On 5/3/18, 6:50 AM, "Pedro Larroy" <pedro.larroy.li...@gmail.com> wrote:
>
> It's very difficult to reproduce, non-deterministic. We were also
> running
> without signal handlers in CI so there are no stack traces
> unfortunately.
>
> Care to elaborate why valgrind doesn't work with Python?
>
>
>
> On Thu, May 3, 2018 at 3:32 PM, Da Zheng <zhengda1...@gmail.com>
> wrote:
>
> > can we build it in CI？segfault doesn't happen infrequently.
> >
> > 2018年5月2日 下午11:34，"Chris Olivier" <cjolivie...@gmail.com>写道：
> >
> > > you can try Intel Inspector, which is like an enhanced version of
> > valgrind
> > > with a GUI and whatnot.
> > >
> > > On Wed, May 2, 2018 at 9:42 PM Da Zheng <zhengda1...@gmail.com>
> wrote:
> > >
> > > > valgrind doesn't work with Python. also, valgrind doesn't
> support some
> > > > CPU instructions used by MXNet (I think some instructions
> related to
> > > > random generator).
> > > >
> > > >
> > > > On Wed, May 2, 2018 at 8:59 PM, Bhavin Thaker <
> bhavintha...@gmail.com>
> > > > wrote:
> > > > > Have you tried running with valgrind to get some clues on the
> > > root-cause?
> > > > >
> > > > > Bhavin Thaker.
> > > > >
> > > > > On Wed, May 2, 2018 at 8:55 PM Da Zheng <zhengda1...@gmail.com
> >
> > wrote:
> > > > >
> > > > >> It might also be possible that this isn't an MKLDNN bug.
> > > > >> I just saw a similar memory error without MKLDNN build.
> > > > >>
> > > > >>
> > > > http://jenkins.mxnet-ci.amazon-ml.com/blue/
> organizations/jenkins/
> > > incubator-mxnet/detail/PR-10783/1/pipeline
> > > > >>
> > > > >> Best,
> > > > >> Da
> > > > >>
> > > > >> On Wed, May 2, 2018 at 2:14 PM, Zheng, Da <dzz...@amazon.com>
> > wrote:
> > > > >> > There might be a race condition that causes the memory
> error.
> > > > >> > It might be caused by this PR:
> > > > >> > https://github.com/apache/incubator-mxnet/pull/10706/files
> > > > >> > This PR removes MKLDNN memory from NDArray.
> > > > >> > However, I don't know why this causes memory error. If
> someone is
> > > > using
> > > > >> the memory, it should still hold the memory with shared
> pointer.
> > > > >> > But I do see the memory error increase after this PR is
> merged.
> > > > >> >
> > > > >> > Best,
> > > > >> > Da
> > > > >> >
> > > > >> > On 5/2/18, 12:26 PM, "Pedro Larroy" <
> > pedro.larroy.li...@gmail.com>
> > > > >> wrote:
> > > > >> >
> > > > >> > I couldn't reproduce locally with:
> > > > >> >
> > > > >> > ci/build.py -p ubuntu_cpu /work/runtime_functions.sh
> > > > >> > build_ubuntu_cpu_mkldnn && ci/build.py --platform
> ubuntu_cpu
> > > > >> > /work/runtime_functions.sh unittest_ubuntu_python2_cpu
> > > > >> >
> > > > >> >
> > > > >> > On Wed, May 2, 2018 at 8:50 PM, Pedro Larroy <
> > > > >> pedro.larroy.li...@gmail.com>
> > > > >> > wrote:
> > > > >> >
> > > > >> > > Hi
> > > > >> > >
> > > > >> > > Seems master is not running anymore, there's a
> segmentation
> > > > fault
> > > > >> using
> > > > >> > > MKDLNN-CPU
> > > > >> > >
> > > > >> > >
> > > > http://jenkins.mxnet-ci.amazon-ml.com/blue/
> organizations/jenkins/
> > > > >> > > incubator-mxnet/detail/master/801/pipeline/662
> > > > >> > >
> > > > >> > >
> > > > >> > > I see my PRs failing with a similar error.
> > > > >> > >
> > > > >> > > Pedro
> > > > >> > >
> > > > >> >
> > > > >> >
> > > > >>
> > > >
> > >
> >
>
>
>
