[erlang-questions] How can I release beam process memory?

Lukas Larsson <>
Sun Jan 15 18:26:22 CET 2017


Hello Frank,

On Sun, Jan 15, 2017 at 12:03 AM, Frank Muller <>
wrote:

> I would appreciate if the OTP team can teach us how to debug VM's mem
> issues, and  how pick the right allocator.
>

The right allocator is the default allocator. It is only in very rare
circumstances that you would want to change it. Sure you can optimize them
to be more perfect, but in most cases the defaults are great.

If you suspect that you have issues that tuning erts_alloc will solve the
best starting points is to read and understand Fred Hebert's excellent
blogs/manuals about using erts_alloc to combat memory fragmentation. I
cannot stress enough how great a resource his blog post (
https://blog.heroku.com/logplex-down-the-rabbit-hole) and manual (
https://www.erlang-in-anger.com/) are.

Then you may also want to watch mine and Rickard Green's/Patrik Nyblom's
talks on the subject, they basically cover the same things that Fred
covers, but some parts in greater detail. There is also some internal
documentation in
https://github.com/erlang/otp/tree/master/erts/emulator/internal_doc that
explain some of the features that you can tune in erts_alloc. There are
also quite a few mail conversations on this mailing list about these types
of problems.

When it comes to allocator tuning there is no magic formula. We attempted
to build something that automatically tuned the settings in the instrument
module (http://erlang.org/doc/man/instrument.html), but it didn't turn out
very useful. The problems that to pop up with erts_alloc seem to be very
different in both symptoms and solutions.

If you explain what it is that you have issues with (backing the claims
with recon_alloc statistics) and what solutions you have tried then we'll
very likely answer.

Lukas
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