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Why Are Parallel GC Threads Still Running after Migrating from Parallel GC to G1GC (Doc ID 2752114.1)

Last updated on SEPTEMBER 19, 2021

Applies to:

Java SE JDK and JRE - Version 8 and later
Information in this document applies to any platform.


After changing the garbage collector (GC) from the default Parallel GC to the Garbage First GC (G1GC), a JVM thread dump shows two types of GC threads running at the same time: G1GC Concurrent threads and Parallel GC threads.


Does this mean that both Parallel GC and G1GC are now running at the same time?  Why was Parallel GC not disabled when the flag -XX:+UseG1GC was added?


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