IntelliJ IDE High Memory Usage. ZGC is in use.

Symptoms

• ZGC is defined in .vmoptions (-XX:+UseZGC)
• Memory consumption is high (more than an expected according to formula in memory allocation)

Cause

ZGC is designed for low-latency systems and can cnsume more memory than default G1GC

IntelliJ IDEA, by default, uses G1GC (G1 Garbage Collector), which is optimized for mixed workloads but with lower memory consumption.

Resolution

Switch to the default garbage collector G1GC:

1. Open Settings
2. Replace -XX:+UseZGC with -XX:+UseG1GC in .vmoptions file