palloc

palloc is a general purpose allocator with excellent performance characteristics. Originally developed as mimalloc, it is designed to be a drop-in replacement for the standard malloc and can be used in projects without code changes.

Key Features

• Small and Consistent: The library is about 10k LOC using simple and consistent data structures.
• High Performance: Outperforms many leading allocators in various benchmarks with low internal fragmentation.
• Free List Sharding: Uses multiple free lists per page to reduce contention and increase locality.
• Secure: Can be built in secure mode with guard pages and other mitigations.
• First-Class Heaps: Efficiently create and use multiple heaps across different threads.
• Broad Compatibility: Supports Windows, macOS, Linux, WASM, and various BSDs.

Quick Start

Building on Linux / macOS

mkdir -p build
cd build
cmake ..
cmake --build .
sudo cmake --install .

Using Ninja for a faster build:

cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build
sudo cmake --install build

Building on Windows

Using Visual Studio (MSVC):

1. Open a Developer Command Prompt for VS or ensure cl and cmake are on PATH.
2. From the repo root:

cmake -B build -G "Visual Studio 17 2022" -A x64
cmake --build build --config Release
cmake --install build --prefix C:\palloc-install

For 32-bit use -A Win32; for ARM64 use -A ARM64.

Using MinGW (GCC on Windows):

cmake -B build -G "MinGW Makefiles" -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++
cmake --build build
cmake --install build

Windows DLL override: To use palloc as a drop-in replacement (override malloc/free) when building the shared library, the build uses a redirect DLL. If bin/ does not already contain palloc-redirect.dll and palloc-redirect.lib, they are built from source (see bin/BUILD.md). To build without the redirect (no override), use:

cmake -B build -DPA_WIN_REDIRECT=OFF ...

Static and shared libraries will still be built; only the runtime redirect for overriding other DLLs is disabled.

Effective build options (Linux and Windows):

Option	Default	Description
CMAKE_BUILD_TYPE	Release	Release, Debug, RelWithDebInfo
CMAKE_INSTALL_PREFIX	system-dependent	Install location (e.g. /usr/local, C:\palloc)
PA_BUILD_SHARED	ON	Build shared library (.so / .dll)
PA_BUILD_STATIC	ON	Build static library (.a / .lib)
PA_BUILD_TESTS	ON	Build test executables
PA_OVERRIDE	ON	Enable malloc/free override (see platform notes above)
PA_WIN_REDIRECT	ON (Windows)	Use redirect DLL for override on Windows; set OFF if bin/ redirect DLLs are missing
PA_OPT_ARCH	OFF (x64), ON (arm64)	Architecture-specific optimizations (e.g. arm64: fast atomics)
PA_PADDING	OFF	Extra padding per block (detect overflow; costs throughput)
PA_SECURE	OFF	Security mitigations (costs throughput)
PA_DEBUG / PA_DEBUG_FULL	OFF	Assertions and invariant checks (costs throughput)

Maximum throughput (benchmarks): Use the release-maxperf preset so padding, secure, and debug are off and PA_OPT_ARCH is on:

cmake --preset release-maxperf && cmake --build build

See doc/PERFORMANCE.md for the full performance guide and an improvement roadmap for weak scenarios.

Run cmake -B build -L to list all cache variables.

CI builds and tests palloc on Linux (Ninja) and Windows (MSVC and MinGW) on every push; see .github/workflows/build.yml.

Usage

• Linux/macOS: Link with libpalloc and include <palloc.h>. For process-wide override without recompiling, use LD_PRELOAD (Linux) or DYLD_INSERT_LIBRARIES (macOS).
• Windows: Link with palloc.lib (or use the static library), include <palloc.h>, and ensure palloc.dll (and, if using override, palloc-redirect.dll) are next to your executable. See bin/readme.md for override details.

# Example (Linux/macOS)
gcc -o myprogram myfile.c -lpalloc

# Example (Windows, MSVC: link with palloc and ensure palloc.dll is in the same folder)
cl myfile.c /I path\to\palloc-install\include path\to\palloc-install\lib\palloc.lib

For more detailed documentation, please refer to the doc/ directory or visit the project documentation.

Benchmark Results

The suite compares palloc against system (glibc), mimalloc, and tcmalloc across 13 scenarios (single-thread, multi-thread, mixed sizes, realloc, fragmentation, etc.). Run it yourself:

cd bench
bash run_bench.sh                    # full run (or --iter=50000 for a quick run)
# Outputs: build/results.csv, build/results_all.json, build/results_report.md

License

This project is licensed under the MIT License - see the LICENSE file for details.