java.lang.management

Class MemoryUsage

Inhoudsopgave

  • public class MemoryUsage
extends Object
    A MemoryUsage object represents a snapshot of memory usage. Instances of the MemoryUsage class are usually constructed by methods that are used to obtain memory usage information about individual memory pool of the Java virtual machine or the heap or non-heap memory of the Java virtual machine as a whole.

    A MemoryUsage object contains four values:

      init represents the initial amount of memory (in bytes) that the Java virtual machine requests from the operating system for memory management during startup. The Java virtual machine may request additional memory from the operating system and may also release memory to the system over time. The value of init may be undefined.
      used represents the amount of memory currently used (in bytes).
      committed represents the amount of memory (in bytes) that is guaranteed to be available for use by the Java virtual machine. The amount of committed memory may change over time (increase or decrease). The Java virtual machine may release memory to the system and committed could be less than init. committed will always be greater than or equal to used.
      max represents the maximum amount of memory (in bytes) that can be used for memory management. Its value may be undefined. The maximum amount of memory may change over time if defined. The amount of used and committed memory will always be less than or equal to max if max is defined. A memory allocation may fail if it attempts to increase the used memory such that used > committed even if used <= max would still be true (for example, when the system is low on virtual memory).

      Eerste pagina van API Java Inhoudsopgave Haut

    Below is a picture showing an example of a memory pool: 

            +----------------------------------------------+
        +////////////////           |                  +
        +////////////////           |                  +
        +----------------------------------------------+

        |--------|
           init
        |---------------|
               used
        |---------------------------|
                  committed
        |----------------------------------------------|
                            max

    MXBean Mapping

    MemoryUsage is mapped to a CompositeData with attributes as specified in the from method.
    Since:
    1.5

    • Constructor Detail

      • MemoryUsage

        public MemoryUsage(long init,
           long used,
           long committed,
           long max)
        Constructs a MemoryUsage object.
        Parameters:
        init - the initial amount of memory in bytes that the Java virtual machine allocates; or -1 if undefined.
        used - the amount of used memory in bytes.
        committed - the amount of committed memory in bytes.
        max - the maximum amount of memory in bytes that can be used; or -1 if undefined.
        Throws:
        IllegalArgumentException - if
        • the value of init or max is negative but not -1; or
        • the value of used or committed is negative; or
        • used is greater than the value of committed; or
        • committed is greater than the value of max max if defined.

    • Method Detail

      • getInit

        public long getInit()
        Returns the amount of memory in bytes that the Java virtual machine initially requests from the operating system for memory management. This method returns -1 if the initial memory size is undefined.
        Returns:
        the initial size of memory in bytes; -1 if undefined.

      • getUsed

        public long getUsed()
        Returns the amount of used memory in bytes.
        Returns:
        the amount of used memory in bytes.

      • getCommitted

        public long getCommitted()
        Returns the amount of memory in bytes that is committed for the Java virtual machine to use. This amount of memory is guaranteed for the Java virtual machine to use.
        Returns:
        the amount of committed memory in bytes.

      • getMax

        public long getMax()
        Returns the maximum amount of memory in bytes that can be used for memory management. This method returns -1 if the maximum memory size is undefined.

        This amount of memory is not guaranteed to be available for memory management if it is greater than the amount of committed memory. The Java virtual machine may fail to allocate memory even if the amount of used memory does not exceed this maximum size.

        Returns:
        the maximum amount of memory in bytes; -1 if undefined.

      • toString

        public String toString()
        Returns a descriptive representation of this memory usage.
        Overrides:
        toString in class Object
        Returns:
        a string representation of the object.

      • from

        public static MemoryUsage from(CompositeData cd)
        Returns a MemoryUsage object represented by the given CompositeData. The given CompositeData must contain the following attributes:

        Attribute Name Type
        init java.lang.Long
        used java.lang.Long
        committed java.lang.Long
        max java.lang.Long

        Eerste pagina van API Java Inhoudsopgave Haut

        Parameters:
        cd - CompositeData representing a MemoryUsage
        Returns:
        a MemoryUsage object represented by cd if cd is not null; null otherwise.
        Throws:
        IllegalArgumentException - if cd does not represent a MemoryUsage with the attributes described above.

Nederlandse vertaling

U hebt gevraagd om deze site in het Nederlands te bezoeken. Voor nu wordt alleen de interface vertaald, maar nog niet alle inhoud.

Als je me wilt helpen met vertalingen, is je bijdrage welkom. Het enige dat u hoeft te doen, is u op de site registreren en mij een bericht sturen waarin u wordt gevraagd om u toe te voegen aan de groep vertalers, zodat u de gewenste pagina's kunt vertalen. Een link onderaan elke vertaalde pagina geeft aan dat u de vertaler bent en heeft een link naar uw profiel.

Bij voorbaat dank.

Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/java-api-rf-java/lang/management/memoryusage.html

De infobrol is een persoonlijke site waarvan de inhoud uitsluitend mijn verantwoordelijkheid is. De tekst is beschikbaar onder CreativeCommons-licentie (BY-NC-SA). Meer info op de gebruiksvoorwaarden en de auteur.

Referenties

  1. Bekijk - html-document Taal van het document:fr Manuel PHP : https://docs.oracle.com

Deze verwijzingen en links verwijzen naar documenten die geraadpleegd zijn tijdens het schrijven van deze pagina, of die aanvullende informatie kunnen geven, maar de auteurs van deze bronnen kunnen niet verantwoordelijk worden gehouden voor de inhoud van deze pagina.
De auteur Deze site is als enige verantwoordelijk voor de manier waarop de verschillende concepten, en de vrijheden die met de referentiewerken worden genomen, hier worden gepresenteerd. Vergeet niet dat u meerdere broninformatie moet doorgeven om het risico op fouten te verkleinen.

Inhoudsopgave Haut