Server Memory
Modes
The performance and behaviour of the Realm Server is
inseparably linked to the amount of maximum heap memory
allocated to the Java VM hosting it. The Realm Server
is capable of scaling depending on the hardware platform
it is hosted on, and that is determined by the memory
available to the Java VM. The Realm detects this and
switches its mode of operation to Small
Memory Mode, Medium Memory
Mode or Large Memory Mode.
Small Memory Mode
Allocating 16MB or less of heap memory to the Java
VM hosting the Nirvana Realm will make it operate in
small memory mode. This is confirmed at start-up by
a log entry like the following:
Audit,Setting Server mode to Small
Memory Mode
The Nirvana Realm small memory mode should be used
when running a Realm on mobile or embedded devices,
or other machines with very limited memory resources
available. Apart from limited memory available to store
events in reliable channels, all thread pooled sub systems
are changed to have only one thread. It is therefore
recommended that persistent channels should always be
used on such Realms. The performance will also be reduced
by the fact that all caching is disabled in this mode.
All of the functionality provided by the innovative
Nirvana server side Realms are available in the small
memory mode and hence on handheld devices etc.
Medium Memory Mode
Allocating 16MB or more of heap memory to the Java
VM hosting the Nirvana Realm will make it operate in
medium memory mode. This is confirmed at start-up by
a log entry like the following:
Audit,Setting Server mode to Medium
Memory Mode
The Nirvana Realm medium memory mode should be used
when running Realms on development or where memory is
at a premium. All thread pooled sub systems will start
up with our recommended default values for this mode.
Tuning the Realm to higher values for those sub systems
will increase the Realm’s memory requirements
and increase caching age values.
Large Memory Mode
Allocating 70MB or more of heap memory to the Java
VM hosting the Nirvana Realm will make it operate in
large memory mode. This is confirmed at start-up by
a log entry like the following:
Audit,Setting Server mode to Large
Memory Mode
The Nirvana Realm large memory mode should be used
when running Realms on development, staging or production
environments, or when using reliable channels. All thread
pooled sub systems will start up with our recommended
default values for this mode.. Tuning the Realm to higher
values for those sub systems will increase the Realm’s
memory requirements and increase caching age values.
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