On Jul 28, 2006, at 21:21, Simon Pepping wrote:

<snip />
IMHO we create a number of circular references in our trees. I have
always feared that we do not clean them up well enough. Are there
tools to investigate this?

In itself a circular reference is not necessarily a problem, I think. As long as the circle gets broken at some point, the allocated heap space will eventually be reclaimed. It's only a matter of _when_ this becomes possible. Currently, it looks like the whole reference tree for all FObjs in all PageSequences is cleared only when the whole document is finished.

In the case of the XMLWhiteSpaceHandler, the reference to the current Block seems to be kept alive slightly too long. The reference is only cleared when replaced by the first block in the next sequence. To allow optimal GC, I think this should be released sooner --end of the page-sequence at the latest. But this would only make a difference if all other references to the PageSequence are also cleared, of course... If not, then the Block is referenced until end-of-document anyway.

I have not yet inspected the layout-tree, but I assume a similar problem is impossible there, as the PageSequenceLM is at the root of each LM-tree. The LM points to its FObj, and not the other way round, so all seems OK.



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