| Garbage collectors: Sometimes you need to take out the trash |
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| Week of June 20, 2022 |
| See how Java’s garbage collectors have evolved from JDK 8 to JDK 18 |
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All garbage collectors do the same basic things. They allocate memory. They detect memory that’s never going to be used again. They then make this unneeded memory available for future allocations.
All garbage collectors do different things, depending on the profile of their applications. Some prioritize allocating memory but are less efficient when it comes to detecting unreachable memory. Some garbage collectors are superfast but require considerable resources, such as memory, from the JVM. Some are less efficient but use less memory.
The three main performance metrics for garbage collectors are throughput, latency, and memory footprint. Java has several garbage collectors, each designed to optimize a specific group of performance metrics.
Thomas Schatzl, a member of Oracle’s garbage collector team, describes the JVM’s Parallel, G1, ZGC, Serial, and Shenandoah garbage collectors, and he details how they have evolved since JDK 8 was released in 2014.
Take care,
Alan Zeichick
Editor in Chief, Java Magazine
@zeichick
P.S. Thomas also discusses Epsilon, which doesn’t satisfy all the requirements of a garbage collector, but which can be useful in some special circumstances. |
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