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jemalloc Buildpack

jemalloc is a general purpose malloc implementation that works to avoid memory fragmentation in multithreaded applications. This buildpack makes it easy to install and use jemalloc on Scalingo and compatible platforms.


scalingo env-set BUILDPACK_URL=

And in a .buildpacks file (example with ruby):

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Set the JEMALLOC_ENABLED config option to true and jemalloc will be used for all commands run inside of your containers.

scalingo env-set JEMALLOC_ENABLED=true

Per container

To control when jemalloc is configured on a per container basis use <cmd> and ensure that JEMALLOC_ENABLED is unset.

Example Procfile:

web: bundle exec puma -C config/puma.rb



Set this to true to automatically enable jemalloc.

scalingo env-set JEMALLOC_ENABLED=true

To disable jemalloc set the option to false. This will cause the application to restart disabling jemalloc.

scalingo env-set JEMALLOC_ENABLED=false


Set this to select or pin to a specific version of jemalloc. The default is to use the latest stable version if this is not set. You will receive an error mentioning tar if the version does not exist.

Default: 5.2.1

note: This setting is only used during slug compilation. Changing it will require a code change to be deployed in order to take affect.

scalingo env-set JEMALLOC_VERSION=3.6.0

Available Versions

Version Released
3.6.0 2015-04-15
4.0.4 2015-10-24
4.1.1 2016-05-03
4.2.1 2016-06-08
4.3.1 2016-11-07
4.4.0 2016-12-04
4.5.0 2017-02-28
5.0.1 2017-07-01
5.1.0 2018-05-08
5.2.0 2019-04-02
5.2.1 2019-08-05

The complete and most up to date list of supported versions and stacks is available on the releases page.


This uses Docker to build against Scalingo stack-image-like images.

make VERSION=5.2.1

Artifacts will be dropped in dist/ based on Scalingo stack and jemalloc version.