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G1 becomes the default garbage collector in JDK 27 for all OpenJDK distributions
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In JDK 27, G1 is now the default garbage collector, heap resizing after full GC is disabled via MinHeapFreeRatio/MaxHeapFreeRatio defaults, and Parallel GC’s tenuring threshold can decrease as well as increase.
This shift removes the need to manually choose a collector for most workloads, simplifying JVM tuning. The altered heap-sizing behavior prevents unnecessary growth-shrink cycles after full GC, and the more flexible tenuring threshold helps Parallel GC retain short-lived objects longer, improving throughput for allocation-heavy applications.
Written by elseif from the cluster below · every claim links back to a sourceThe three things worth knowing
G1 becomes the default garbage collector when no explicit collector is specified on the command line.
After a full GC, G1 no longer adjusts heap size using the MinHeapFreeRatio and MaxHeapFreeRatio flags, whose defaults are now 0% and 100%.
Parallel GC’s adaptive tenuring threshold can now decrease, allowing younger objects to stay longer in the young generation and reducing premature promotions.
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