Database Reference
In-Depth Information
Memory Analyzer
The memory analyzer tool is an open-source product that will help to analyze large product-
ive heap dumps. The tool will help identify which Java objects are hogging large chunks of
memory and will be helpful in identifying the root cause of the heap dumps in your system.
The location to download the tool is provided in the additional resources section of this
chapter.
Summary
• The primary SAP Java memory allocation areas in JVM are young generation memory
area, tenured (old) generation memory area, and permanent generation memory area.
• The young generation memory area keeps the newly created Java objects.
• The tenured (old) generation memory area keeps the Java objects that are in use for a
while and are still needed by the system.
• The permanent memory area keeps central classes and methods permanently.
• Garbage collection is a process of automatic memory allocation and deallocation by
the system using garbage collector algorithms.
• A heap size of 1GB is recommended for 32-bit systems.
• A heap size of 2GB is recommended for 64-bit systems.
• A heap size up to 3.5GB can be configured for 64-bit systems.
• Minor garbage collection is quick and does not have any major performance implica-
tions.
• Full garbage collection is triggered when there is not enough memory to be allocated
in the tenured memory area, and it has major performance implications.
• Out-of-memory errors could result if there is no more memory available for tenured
memory area needs.
• Java server nodes are equivalent to ABAP work processes.
• Java server nodes are multithreaded and therefore can perform multiple tasks at a time.
• ABAP work processes are single-threaded, performing one task at a time.
• Application and system thread counts can be increased for each server node using the
configuration tool.
