Java Reference
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24. Copying garbage collection can be improved by identifying long-lived
heap objects and allocating them in an area of the heap that is not
collected.
What compile-time analyses can be done to identify heap objects that
will be long lived? At runtime, how can we e
ciently estimate the “age”
of a heap object (so that long-lived heap objects can be specially treated)?
25. An unattractive aspect of both mark-sweep and copying garbage collec-
tion is that they are batch-oriented. That is, they assume that periodically
a computation can be stopped while garbage is identified and collected.
In interactive or real-time programs, pauses can be quite undesirable.
An attractive alternative is
concurrent garbage collection
in which a
garbage collection process runs concurrently with a program.
Consider bothmark-sweep and copying garbage collectors. What phases
of each can be run concurrently while a program is executing (that is,
while the program is changing pointers and allocating heap objects)?
What changes to garbage collection algorithms can facilitate concurrent
garbage collection?
