README.md

Glibc Malloc Statistics for the JVM

An utility for retrieving the JVM's malloc statistics when using glibc malloc.

This library calls the mallinfo glibc function via JNI to retrieve the glibc heap statistics. If the mallinfo2 function is available (glibc >= 2.35.0), it is called instead. The reported values may wrap around at signed 32-bits integer boundaries when using mallinfo.

The version of this library published on Maven Central only includes the compiled native JNI wrapper code for x86_64 Linux. If you target any other platform, you have to provide the appropriate native libraries compiled from the glibc-malloc-stats-mallinfo and glibc-malloc-stats-mallinfo2 modules.

Usage

Maven dependency:

<dependency>
    <groupId>io.kemtoa</groupId>
    <artifactId>glibc-malloc-stats</artifactId>
    <version>1.0.0</version>
</dependency>

Usage example:

if (MallocStatsUtils.areStatsAvailable()) {
	MallocStats mallocStats = MallocStatsUtils.getMallocStats();
	System.out.printf("Arena Total Size:                %10s KiB\n", mallocStats.arenaTotalSize() / 1024);
	System.out.printf("Arena Used Size:                 %10s KiB\n", mallocStats.arenaUsedSize() / 1024);
	System.out.printf("Arena Free Size:                 %10s KiB\n", mallocStats.arenaFreeSize() / 1024);
	System.out.printf("Arena Reclaimable Size:          %10s KiB\n", mallocStats.arenaReclaimableSize() / 1024);
	System.out.printf("Arena Free Blocks Count:         %10s\n",     mallocStats.arenaFreeBlocksCount());
	System.out.printf("Arena Free FastBin Blocks Count: %10s\n",     mallocStats.arenaFreeFastBinBlocksCount());
	System.out.printf("Mapped Blocks Count:             %10s\n",     mallocStats.mmapBlocksCount());
	System.out.printf("Mapped Blocks Total Size:        %10s KiB\n", mallocStats.mmapBlocksTotalSize() / 1024);
	System.out.printf("Total C Heap Size:               %10s KiB\n", (mallocStats.arenaTotalSize() + mallocStats.mmapBlocksTotalSize()) / 1024);
}