Errors with LD_PRELOAD version

[gbatterbee]

Hi, thanks for setting up this build pack.

I'm not sure if there is a problem or not, though I would log it here.
We're running
Ruby 2.37
Rails 4.2.0

  "stack": "heroku-16",
  "buildpacks": [
    {
      "url": "heroku/nodejs"
    },
    {
      "url": "heroku/ruby"
    },
    {
      "url": "https://github.com/.../heroku-buildpack-libjpeg62"
    },
    {
      "url": "https://github.com/.../buildpack-ruby-rake-deploy-tasks"
    },
    {
      "url": "https://github.com/mojodna/heroku-buildpack-jemalloc.git"
    }
  ],

As per docs I added Env Var LD_PRELOAD=/app/vendor/jemalloc/lib/libjemalloc.so.1

But this errored with

Jul 29 09:02:37 ...-app-preprod-pr-5439 app/web.1: ERROR: ld.so: object '=/app/vendor/jemalloc/lib/libjemalloc.so.1' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.   

If I run these in bash,

~ $ ldd /app/vendor/jemalloc/lib/libjemalloc.so.1
	linux-vdso.so.1 =>  (0x00007ffcc78ba000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f1853734000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f185336a000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f1853b91000)
~ $ 

So then I checked this

~ $ ls /app/vendor/jemalloc/lib
libjemalloc.a  libjemalloc_pic.a  libjemalloc.so  libjemalloc.so.1
~ $

And changed
LD_PRELOAD to /app/vendor/jemalloc/lib/libjemalloc.so

I then pushed a new change and got a build error.
JSON::ParserError: 784: unexpected token at 'ERROR: ld.so: object '/app/vendor/jemalloc/lib/libjemalloc.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.

So I removed LD_PRELOAD and used
web: jemalloc.sh bundle exec puma -C config/puma.rb

I can push a change through, but querying ~ $ ruby -r rbconfig -e "puts RbConfig::CONFIG['LIBS']"

Gives me -lpthread -lgmp -ldl -lcrypt -lm

So I don't know if this is what is expected or if it is working properly?
If you could confirm if this is correct, or if there is an error here?

Many thanks!

[nateberkopec]

I'm not sure jemalloc is supposed to showup in RbConfig::Config['LIBS'].

Somebody asked me about this before, "how do I know if Jemalloc is actually being used when using LD_PRELOAD", and I don't think there's a great solution.

[gbatterbee]

I had a feeling you were going to say that.
Thanks for the response.

As for the other errors, I guess these never got resolved?
I guess there isn't a know resolution for not being able to use jemalloc.so.1 or for being able to use the LD_PRELOAD env var?

[gaffneyc]

@gbatterbee To see if jemalloc is enabled you can use the trick mentioned in this comment: gaffneyc#5 (comment)

If you're having trouble getting it set up I would recommend taking a look at my fork which should be easier to get started with.

[gbatterbee]

Ah, nice, thanks - I'll take a look.