| Re: [eigen] Memory Leak When Constructor of User-Defined Type Throws Exception |
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On 06.07.2014 07:47, Moritz Klammler wrote:
unfortunately, the Bugzilla server is not functional (I don't know for
how long this might be) so I could not check whether this issue has
already been reported.
This appears to be related to a software update by http://tuxfamily.org/
Jitse is currently investigating.
Currently, if the constructor of a (user-defined) type throws an
exception during construction of a dense matrix with dynamic size, the
memory for the storage of the (not created) matrix is leaked. This is
not a documented [1] limitation for user-defined types so I assume that
it is not intended behavior. (The page also does not mention that
user-defined types must be default-constructible. Although, that might
go without saying.)
Yes, we shall make Eigen leak-proof wherever possible. And we could add
a note to [1] that types must be default-constructible.
I'm confident that modern compilers are smart enough to optimize away
the try-catch block if the Scalar constructor does not throw, however we
need to #ifdef-guard it for platforms which do not support exceptions.
For that we already have:
#ifdef EIGEN_EXCEPTIONS
Attached is a unit test that demonstrates the leak if run through
Valgrind (or some other debugger) as in
It would be nice to have a proper unit-test that actually checks if
everything gets deconstucted properly, maybe by keeping track of
allocations in a static variable. (Also, your unit test will wrongfully
assert with a probability of (10/11)^1288 *g* )
Christoph
[1] http://eigen.tuxfamily.org/dox/TopicCustomizingEigen.html#user_defined_scalars
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Dipl.-Inf., Dipl.-Math. Christoph Hertzberg
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