Java MaxDirectMemorySize

Refer to for detail: https://dzone.com/articles/default-hotspot-maximum-direct-memory-size

1. Java default

java -XX:+PrintFlagsFinal -version

size_t MaxDirectMemorySize                       = 0

2. Randomly need re-configure

-XX:MaxDirectMemorySize=

public static void writeMaximumDirectMemorySizeToStdOut()

{

   final double vmSize =

      MemoryUnit.BYTES.toMegaBytes(VM.maxDirectMemory());

   out.println(

       "sun.misc.VM.maxDirectMemory(): " + vmSize + " MB");

}