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Parameter / Description Default Value
-XX:+DisableExplicitGC
Disables the explicit garbage
collection calls that are caused by
invoking System.gc() inside the
application.
It is recommended that the
developers avoid the System.gc()
calls to cause programmer-initiated,
full-compaction garbage collection
cycles, because such calls can
interfere with the tuning of
resources and garbage collection for
the entire application system. If
your application pause times
caused by System.gc() are more
than your expected pause times, it
is strongly recommended that you
use this option to disable the
explicit GC, so that the System.gc()
calls will be ignored.
For both 32-bit/64-bit noapp and container JVMs:
v Windows = -XX:+DisableExplicitGC
v Solaris = -XX:+DisableExplicitGC
v HP-UX = -XX:+DisableExplicitGC
-XX:NewSize= and -Xmn<Size>=
–XX:NewSize controls the
minimum young generation size in
a heap, and the –Xmn sets the size
of the young generation heap.
It is recommended to use the
following formula to compute -
XX:NewSize and -Xmn values
when the minimum heap size and
maximum heap sizes are modified.
v -XX:NewSize = (0.33333* value of
–Xms)
v -Xmn = (0.33333 * value of -Xmx)
Refer to “Edit Performance Configuration Settings”
on page 123 for the default values for the:
v Initial new heap size for the server JVM
(INIT_AGE)
v Initial new heap size for the container JVM
(INIT_AGE_CONTAINER)
v Maximum new heap size for the server JVM
(MAX_AGE)
v Maximum new heap size for the container JVM
(MAX_AGE_CONTAINER)
-XX:MaxPermSize
Stores all the class code and
class-like data. The value of the
parameter should be large enough
to fit all the classes that are
concurrently loaded. Sometimes, it
is difficult to determine the actual
value of this parameter because
generally, this region is smaller and
expands slowly, and the utilization
is commonly observed at 99-100
percent of its current capacity. If
you have not configured this region
correctly, the JVM might fail with
the Java.lang.OutOfMemoryError:
PermGen space error.
Refer to “Edit Performance Configuration Settings”
on page 123 for the default values for the:
v Maximum permanent generation heap size for the
server JVM (MAX_PERM_SIZE)
v Maximum permanent generation heap size for the
container JVM (MAX_PERM_SIZE_CONTAINER)
68 Sterling B2B Integrator: Performance Management