JVM configuration parameter parsing

  1. Parameter Description (portion to be improved)

 

    -Xms128M: JVM initial allocation of heap memory

    -Xmx256M: JVM maximum allowable allocated heap memory, on-demand

    -XX: PermSize = 64M: JVM initial allocation of non-heap memory

    -XX: MaxPerSize = 128M: JVM maximum allowable non-allocated heap memory, on-demand          

    2. heap memory allocation (-Xms -Xmx)

 

          JVM initial allocation specified by the heap memory -Xms, the default is the 64th of physical memory; maximum allocated heap memory specified by -Xmx, 1/4 default physical memory.

               Default spare stack is less than 40%, JVM stack will increase up to a maximum limit of -Xmx;

       When spare reactor is greater than 70%, JVM stack will be reduced until the minimum limit -Xms;

       Between this case, the server is usually set equal -Xms -Xmx, GC after each adjustment to avoid heap size

          Note: If you do not specify -Xms values ​​or value is too small, the system may throw java.lang.OutOfMemory errors, which comes from the JVM, uncatchable.

   3. Non-heap memory allocation (-XX: PermSize -XX: MaxPermSize)

       JVM initial heap memory allocated by the -XX: Specifies PermSize, the default is the 64th of physical memory; max heap memory allocated by the -XX: Specifies MaxPerSize, 1/4 default physical memory.

               Note: -XX: MaxPermSize set too small will cause a memory overflow java.lang.OutOfMemoryError: PermGen space.

               The cause of this situation:

       (1) Meta and the region class information is stored, into PermGen space class loading area, and instances of objects stored Heap different regions.

                       (2) GC will not clean up of PermGen space in the main program running

    Mainly in the web server jsp pre-compile time.

                                                     -------------------------------- finishing rookie, if wrong, please point out!

                  

 

Guess you like

Origin www.cnblogs.com/kaizhengMan/p/10948409.html