[mythtv] Mythtv pes_malloc and pes_free
roger at beardandsandals.co.uk
Mon May 8 08:16:11 UTC 2017
On 8 May 2017 6:43:32 am Karl Dietz <dekarl at spaetfruehstuecken.org> wrote:
> On 07.05.2017 12:53, Roger James wrote:
>> I would like to propose that we consider reverting to the default heap
>> allocator. There are also a number of alternatives to the ptmalloc
>> allocator that could be consider, for example tcmalloc from Google.
> I like the idea. Do you know if it helps? I just read the other day that
> using the standard implementations may contain some nasty surprises...
> I hear jemalloc (as used in FreeBSD) is great http://jemalloc.net/
Hi Karl, Gary,
The pes_alloc stuff is is only used for allocation of PES packet data and
is of course built on top of malloc. So disabling it does not change our
exposure to malloc bugs. In fact my new code highlighted a very similar
problem in the pes_alloc code to that described by zerotier! My SDT and EIT
changes involve long term caching of PES packet data. Because these long
term allocations are randomly distributed through pes_alloc pools and the
usage profile is rapid increase to an initial peak followed by a slow decay
down to a stable level as knowledge of table section versions is gathered,
we end up with far more allocated pools than we need. So reducing the
number of memory allocators with potentially conflicting allocation
strategies we have layered on top on each other, is always in my view, a
Does it help? Well I have been running it successfully for a couple of days
now. Only time and greater exposure will tell. It is very easy to try it
out, just put #define USING_VALGRIND at the start of pespacket.cpp.
As far as the use of other malloc replacements go I can happily leave that
discussion to you guys. I just want to get back to working on what I wanted
to do many months ago, having a look at accurate scheduling using now next
transitions and running status data!
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