2

I've built and installed rub 2.6.5 from source with jemalloc. However when I check to see if its there I'm not seeing an entry. Is there something else I should have been doing?

ubuntu:~$ uname -a
Linux ip-10-0-3-198 4.15.0-1032-aws #34-Ubuntu SMP Thu Jan 17 15:18:09 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
ubuntu:~$ ./configure --enable-shared --with-jemalloc
ubuntu:~$ make
ubuntu:~$ make install

Which results in:

ubuntu:~$ ruby -r rbconfig -e "puts RbConfig::CONFIG['LIBS']"
-lm

Tracking memory usage once deployed I'm also not seeing a drop compared to similarly configured servers without jemalloc in place.

I'm not sure what I need to be doing in order to get jemalloc working.

Thanks!

Lloyd Watkin
  • 485
  • 4
  • 10

3 Answers3

6

Try:

puts RbConfig::CONFIG['MAINLIBS']

And check for -ljemalloc in the output.

This behavior has changed recently (in 2.6.x, to be precise).

Marek Lipka
  • 50,622
  • 7
  • 87
  • 91
  • Thanks! I do indeed see `jemalloc` in the list: "$ ruby -r rbconfig -e "puts RbConfig::CONFIG['MAINLIBS']" -lz -lpthread -lrt -lrt -ljemalloc -lgmp -ldl -lcrypt -lm" – Lloyd Watkin Dec 03 '19 at 10:20
  • Thanks. Sadly not really seeing an improvement in memory usage though. Back to the investigation. – Lloyd Watkin Dec 03 '19 at 11:53
6

For some reason, the accepted answer does not work for me (Heroku), but this:

MALLOC_CONF=stats_print:true ruby -e "exit"

has done the trick.

If you have some stats ouput, means it's working.

source: https://github.com/gaffneyc/heroku-buildpack-jemalloc/issues/5#issuecomment-499932026

Paulo Fidalgo
  • 21,709
  • 7
  • 99
  • 115
0

For ones using LD_PRELOAD and not building ruby directly, a more complete answer would be:

RbConfig::CONFIG['MAINLIBS'].include?("jemalloc") || ENV['LD_PRELOAD'].include?("jemalloc")

Of course this is not enough to tell if jemalloc really is working, as for the accepted answer!

Ulysse BN
  • 10,116
  • 7
  • 54
  • 82