Robin, thank you for this information. I want to ask a few questions to check that I understand you correctly.
On 10/31/06, Robin Garner <[EMAIL PROTECTED]> wrote:
MMTk implements several algorithms for retaining the reachable objects in a graph and recycling space used by unreachable ones. It relies on the host VM to provide a set of roots. It supports several different semantics of 'weak' references, including but not confined to those required by Java. If you can implement class unloading using those (which the current proposal does), then MMTk can help. If you want to put a pointer to the j.l.Class in the object header, MMTk will not care, as it has no way of knowing. If you put an additional pointer into the body of every object, then MMTk will see it as just another object to scan.
Does this mean that MMTk will not work with VM in which VTable pointer (a pointer in object header) points to other heap object?
Remember MMTk is a memory manager, not a Java VM! Conversely, supporting some exotic class unloading mechanism in MMTk shouldn't be hard and wouldn't deter me from trying it out. If (as a wild idea) you wanted to periodically scan the heap, and count all references to each classloader, you could implement this with very little work as a TraceLocal object, and then extend the GC plan you wanted with an additional GC phase that would periodically do one of these scans after a major GC (for example).
This looks similar to approach #2 discussed here, agree? -- Ivan Intel Enterprise Solutions Software Division
