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At Startup a Java Task's Reported Resident Memory Usage is Less Than Its Minimum Heap Memory Specified by the -Xms Parameter (Doc ID 1557712.1)

Last updated on FEBRUARY 21, 2018

Applies to:

Oracle Communications Converged Application Server - Version 2.1.0 and later
Oracle WebLogic Server - Version 6.1 and later
Java SE JDK and JRE - Version 1.3.1 and later
Oracle JRockit - Version 7.0 and later
Generic Linux
Generic UNIX


On a *NIX server, a JVM (Java Virtual Machine) started with a memory argument of -Xms2G (minimum Java heap memory size), reports 1.0G of resident memory is in use, as reported by commands such as top (RES column), ps aux, or pmap (RSS column).  After heavy loading of the JVM, the resident memory usage reported increases to greater then 2.1G resident memory usage (as expected).

Why does Java not preallocate all its minimum heap memory on startup, as specified by the -Xms memory argument?


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