Hi, all, the plan for GCv5 parallel compaction is to apply the idea of Compressor [1]. But it has an issue I want to discuss with you. Compressor needs to reserve an unmapped virtual space for compaction. The size of the reserved part is the same as that of copy reserve space in a semi-space collector. This means about that part of the virtual space is unusable for the JVM. In a typical setting, the wasted part is half size of the total compaction space. If we have 1GB physical memory, the JVM is ok for Compressor because the virtual space is large enough to wast half; but if the phsical memory is >2GB, Compressor may have a problem in 32bit machine: some of phsical mapped space might be wasted.
Any opinion on this? Thanks, xiaofeng [1] http://www.cs.technion.ac.il/~erez/Papers/compressor-pldi.pdf
