Nulling Out References Won't Help Your Garbage Collector

Thu, 09 Jul 2026 13:49:39 +0000

One of the misconceptions that I continuously run into is that nulling out references in Java helps garbage collection.

This attitude is particularly prevalent from those developers used to C/C++ where delete ptr becomes ref = null. To be fair, it’s a reasonable thing to believe.

It’s also wrong, and the way it’s wrong tells you most of what’s worth knowing about how a tracing collector actually works.

That is, the vast majority of data allocated in a tracing garbage collected runtime becomes collectable as soon as a variable falls out of scope.

Kirk Pepperdine on foojay.io - Friends of OpenJDK

Nulling Out References Won't Help Your Garbage Collector