7.2.1 Objectives of using the Explicit Memory Management functionality
The Explicit Memory Management functionality is a function that suppresses occurrence of Full GC. By using this function, you can reduce the frequency of system halts and achieve a stable throughput.
The size of a Java heap handle on Application Server is increased by increasing the logical address space handled in the system or by expanding the system scale. It is a problem that the time required for GC increases as the Java heap size increases. While GC is being performed, system operation stops. Especially, the time required for Full GC increases according to the size of the used Java heap area. This also means that increasing the size of the available Java heap can increase the time required for Full GC accordingly.
- Reference note
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- Relationship between the GC algorithm and system downtime
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The Java VM supports Copy as the algorithm for copy GC and Mark Sweep Compact as the algorithm for Full GC. Both of these algorithms are of Stop-The-World type. With the algorithm of this type, GC requires the same time as the downtime of the system that uses the Java VM.