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Problem(Abstract) |
Setting the initial Java™ heap size too high can result in
inefficient garbage collection and heap compaction. This is because by the
time garbage collection is performed, the heap is very large and is
probably fragmented. Therefore, the IBM® WebSphere® Application Server Xms
setting should not be set equal to the Xmx setting. |
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Cause |
Inefficient garbage collection. |
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Resolving the
problem |
Setting the initial Java heap minimum equal to the Java
heap maximum is not recommended. Doing so can delay the start of garbage
collection until the heap is full. Therefore, the first time the Garbage
Collector runs is a very expensive operation.
The heap is also likely to be very fragmented by the time heap compaction
is required. This is also a very expensive operation.
IBM recommends that you start your application with the minimum heap size
needed. When it starts up, the Garbage Collector will run often and
because the heap is small, it runs efficiently.
But this is not a "one recommendation fits all cases" solution. Some
applications might require setting the initial Java heap minimum equal to
the Java heap maximum. |
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