Android的摇篮：什么是javaMaxHeapSize＆QUOT;4克＆QUOT;？ [英] Android Gradle: What is javaMaxHeapSize "4g"?

问题描述

在一个Android项目， 的build.gradle 的文件，我已经通过此行

In an android project, build.gradle file, I have been through this line

dexOptions{
    javaMaxHeapSize "4g"
}

我想知道确切的目的，此 javaMaxHeapSize 并又有什么4克表示。什么是其他值我可以给？

I would like to know the exact purpose of this javaMaxHeapSize and what does that 4g means. What are other values I can give ?

推荐答案

由于它在回答上面提到的，只是，以指定的最大存储器分配池用于塞米松动作的Java虚拟机（JVM）的选项。而且它是相同的，以提供对Java的 -Xmx 参数。由于它的源$ C ​​$ CS由<一个href=\"https://android.googlesource.com/platform/tools/build/+/master/gradle/src/main/groovy/com/android/build/gradle/internal/dsl/DexOptionsImpl.groovy\">here,它的制定者的样子：

As it mentioned in the answer above, it is just an option to specify the maximum memory allocation pool for a Java Virtual Machine (JVM) for dex operation. And it's the same, as to provide to java the -xmx argument. Due to it's source codes from here, it's setter look like:

if (theJavaMaxHeapSize.matches("\\d+[kKmMgGtT]?")) {
    javaMaxHeapSize = theJavaMaxHeapSize
} else {
    throw new IllegalArgumentException(
            "Invalid max heap size DexOption. See `man java` for valid -Xmx arguments.")
}

所以，你可以看到，所接受的值应该匹配 \\ D + kKmMgGtT] 模式，因此没有，甚至指男人的java 结识，如何设置 -Xmx 。您可以阅读 href=\"http://docs.oracle.com/javase/6/docs/technotes/tool​​s/solaris/java.html\">手册页。它说，这标志：

So, you can see, that the accepted value should match the \d+[kKmMgGtT]? pattern, and hence not, it even refers to the man java to get to know, how to set the -xmx. You can read the man page here. And it says, that this flag:

指定的最大大小，以字节为单位的内存分配池。该值必须是1024的倍数大于2MB。追加字母k或K来表示千字节，m或M来表示兆字节。默认值是根据系统配置选择在运行时。

Specify the maximum size, in bytes, of the memory allocation pool. This value must a multiple of 1024 greater than 2MB. Append the letter k or K to indicate kilobytes, or m or M to indicate megabytes. The default value is chosen at runtime based on system configuration.

在你的榜样，4克 4 GB的，这是DEX操作的最大堆大小。

In your example, 4g is 4 Gigabytes and this is a maximum heap size for dex operation.

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