By default all plugins are enabled and built as dynamic .so (or .dll) modules. If a plugin does not support dynamic builds, it is not built at all.

Use PLUGIN_xxx cmake variables. They can be set on the command line with -DPLUGIN_xxx=value or in the cmake gui. Supported values are

Note that unlike autotools, cmake tries to configure and build incrementally. You can modify one configuration option and cmake will only rebuild the part of the tree affected by it. For example, when you do cmake -DWITH_EMBEDDED_SERVER=1 in the already-built tree, it will make libmysqld to be built, but no other configuration options will be changed or reset to their default values.

In particular this means that if you have run, for examplecmake -DPLUGIN_OQGRAPH=NO and later you want to restore the default behavior (with OQGraph being built) in the same build tree, you would need to runcmake -DPLUGIN_OQGRAPH=DYNAMIC

Alternatively, you might simply delete the CMakeCache.txt file — this is the file where cmake stores current build configuration — and rebuild everything from scratch.

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Using tcmalloc or jemalloc

is a malloc replacement library optimized for multi-threaded usage. It features a built-in heap debugger and profiler. Another malloc replacement that can speed up MariaDB is .

The procedures to use one of these libraries with MariaDB are the same. Many other malloc replacement libraries (as well as heap debuggers and profilers) can be used with MariaDB in a similar fashion.

Prerequisites

jemalloc is a powerhouse for reducing memory fragmentation and improving concurrency, but it isn't a "one-size-fits-all" drop-in for every environment. Its availability and stability depend heavily on how the operating system handles memory pages and how MariaDB was compiled.

Operating System Availability

• Linux: Jemalloc is most at home here. Most major distributions (Ubuntu, Debian, CentOS/RHEL, Arch) include it in their official repositories (libjemalloc2 or jemalloc). It is the standard recommendation for high-traffic MariaDB setups on Linux.

• Windows: Jemalloc does not have the same "native" presence on Windows. While the jemalloc source code can technically be compiled for Windows using MSVC or MinGW, MariaDB for Windows is almost exclusively used with the default Windows system allocator. Most DBAs do not use jemalloc on Windows production servers.

Hardware and Architecture Hurdles

One of the most common "hidden" failures occurs on non-x86 architectures:

• Raspberry Pi (ARM): On newer devices like the Raspberry Pi 5, jemalloc often fails to start with the error: <jemalloc>: Unsupported system page size. This happens because jemalloc is frequently compiled assuming a 4KB page size, while many ARM kernels now use 16KB or 64KB pages for better performance.

• Cloud Instances: Small instances (like AWS t2.micro) can sometimes behave unpredictably with jemalloc if they lack sufficient swap space or if the memory overhead of the

Compatibility Matrix Summary

Check if it's Ready to Use

Before trying to force it via LD_PRELOAD, check if the library even exists on your system paths:

If these commands return nothing, you need to install the package first (sudo apt install libjemalloc2 or sudo dnf install jemalloc).

Why Use it

The main reason to switch isn't just speed, but fragmentation. Standard malloc can leave small gaps of unused memory that the OS can't reclaim, leading to "memory bloat" where MariaDB appears to use 10GB of RAM even if the data only needs 6GB. Jemalloc is much better at packing these allocations tightly.

Checking the malloc Implementation in Use

To check which malloc implementation is used, run this query:

A value of system indicates the system default, which is normally malloc. If another library is used, the name and version of the library is shown.

Building MariaDB With an Alternative to malloc

To build MariaDB with TCMalloc, you need to use the following command:

To use jemalloc, specify -ljemalloc instead of -ltcmalloc.

Starting mariadbd-safe With an Alternative to malloc

Start a standard MariaDB server with TCmalloc like this:

To configure to use tcmalloc or jemalloc, add this to your :

Starting mariadbd With an Alternative to malloc

Locate the library file that needs to be used:

Pass that library file to mariadbd using the LD_PRELOAD variable:

Configuring systemd

If you use systemd to run MariaDB, locate the library as explained above, then locate the service configuration file:

Edit the mariadb.service file by adding a line to the [Service] group:

For example, add this:

Reload the configuration for the news setting to take effect, and restart MariaDB:

Dockerfile

If you run and use an image from a Dockerfile that is publicly available, most probably you have an entry point that is a bash script, which starts mariadbd directly. Edit that bash script, or set the LD_PRELOAD variable from the Dockerfile:

To find the library file, run one of these commands while the container is running:

Example:

Vagrantfile

Usually is used to start a complete system in a virtual machine. In that case, you can use one of the methods above, for example you can modify your Vagrantfile to copy a modified version of the mariadb.service file to the guest system to configure systemd.

If you use Vagrant with the Docker provider, you can follow the instructions above to modify the Dockerfile.

Making jemalloc Persistent

To make MariaDB use jemalloc persistently, set it up like this. These instructions work on Linux using systemd and running on an x86 architecture.

Steps

Notes

systemctl edit creates a separate configuration file (/etc/systemd/system/mariadb.service.d/override.conf). systemd always prioritizes settings in override files over the main service file (/usr/lib/systemd/system/mariadb.service).

When upgrading MariaDB, the package manager only replaces or updates the main service file. Your custom override file in /etc/systemd/system/mariadb.service.d/ remains untouched, thus preserving your jemalloc configuration.

systemd reads all its service configurations, including override files, on system start. This means the LD_PRELOAD environment variable is set for MariaDB automatically each time the service starts, making the change persistent across reboots.

Finding memory leaks with jemalloc

jemalloc provides a report of memory leaks at program exit:

This produces output like this:

You can learn more about the memory leaks with jeprof, which is shipped with jemalloc:

You can also generate a PDF call graph of the leak:

See Also

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