查看当前JRE默认堆大小（default Heap size）

?下面两个命令用于查看当前JRE默认的堆大小，该方法适用于Java 6u20以及之后版本。

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# 使用-server

java -server -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version | grep -i heapsize
uintx ErgoHeapSizeLimit = 0 {product}
uintx InitialHeapSize := 519327936 {product}
uintx LargePageHeapSizeThreshold = 134217728 {product}
uintx MaxHeapSize := 8311013376 {product}
java version "1.6.0_27-ea"
Java(TM) SE Runtime Environment (build 1.6.0_27-ea-b01)
Java HotSpot(TM) 64-Bit Server VM (build 20.2-b01, mixed mode)

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# 使用-client
java -client -XX:+UnlockDiagnosticVMOptions -XX:+PrintFlagsFinal -version | grep -i heapsize uintx ErgoHeapSizeLimit = 0 {product}
uintx InitialHeapSize := 519327936 {product}
uintx LargePageHeapSizeThreshold = 134217728 {product}
uintx MaxHeapSize := 8311013376 {product}
java version "1.6.0_27-ea"
Java(TM) SE Runtime Environment (build 1.6.0_27-ea-b01)
Java HotSpot(TM) 64-Bit Server VM (build 20.2-b01, mixed mode)

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参考：

http://dow.ngra.de/2011/01/12/what-are-the-default-xmx-and-xms-values/

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-- heipark

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