[SOLVED] jemalloc MALLOC_CONF values not reflecting when I run MEMORY MALLOC-STATS in Redis

jemalloc MALLOC_CONF values not reflecting when I run MEMORY MALLOC-STATS in Redis

I am trying to set some tunables for jemalloc at runtime, before launching Redis.

http://jemalloc.net/jemalloc.3.html#tuning : Says that I can set the environment variable MALLOC_CONF. This is how I am doing that.

I run export MALLOC_CONF=narenas:40 in my shell, then I launch the redis-server like so ./src/redis-server --port 8088

However, if I connect to this redis server using the redis-cli and run MEMORY MALLOC-STATS I see this output:

___ Begin jemalloc statistics ___
Version: "5.3.0-0-g0"
Build-time option settings
  config.cache_oblivious: false
  config.debug: false
  config.fill: true
  config.lazy_lock: false
  config.malloc_conf: ""
  config.opt_safety_checks: false
  config.prof: false
  config.prof_libgcc: false
  config.prof_libunwind: false
  config.stats: true
  config.utrace: false
  config.xmalloc: false
Run-time option settings
  opt.abort: false
  opt.abort_conf: false
  opt.cache_oblivious: false
  opt.confirm_conf: false
  opt.retain: true
  opt.dss: "secondary"
  opt.narenas: 160
  [... output continues]

Clearly the narenas parameter is still set to its default value.

Am I completely misunderstanding how to set the value of this env variable?

I expected the value of opt.narenas to be set to 40 not 160

Solution

So it turns out that when you build redis on my system, it sets --with-jemalloc-prefix=je_, which means that all of jemalloc's public APIs become prefixed with the string je_ (or JE_)

Running export JE_MALLOC_CONF=narenas:40 then results in the expected behavior.

The prefix behavior is described here : https://github.com/jemalloc/jemalloc/blob/dev/INSTALL.md