gh-93618: Document the memory usage of the incremental parsers - #156763
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serhiy-storchaka merged 1 commit intoSep 13, 2026
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It was said that iterparse() can be useful for reading a large document without holding it wholly in memory, but the tree is only built incrementally, it is not freed incrementally. Document how to remove the processed elements, and that a custom target does not build a tree at all.
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Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15. |
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GH-157419 is a backport of this pull request to the 3.15 branch. |
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GH-157420 is a backport of this pull request to the 3.14 branch. |
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GH-157421 is a backport of this pull request to the 3.13 branch. |
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…GH-156763) (GH-157420) It was said that iterparse() can be useful for reading a large document without holding it wholly in memory, but the tree is only built incrementally, it is not freed incrementally. Document how to remove the processed elements, and that a custom target does not build a tree at all. (cherry picked from commit e7a3937) Co-authored-by: Serhiy Storchaka <[email protected]>
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…GH-156763) (GH-157421) It was said that iterparse() can be useful for reading a large document without holding it wholly in memory, but the tree is only built incrementally, it is not freed incrementally. Document how to remove the processed elements, and that a custom target does not build a tree at all. (cherry picked from commit e7a3937) Co-authored-by: Serhiy Storchaka <[email protected]>
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The documentation said that
iterparse()"can be useful when you're reading a large XML document and don't want to hold it wholly in memory", but the tree is only built incrementally, it is not freed incrementally: every parsed element is kept until the whole document is read.The claim is replaced with an explanation and two examples for common cases: clearing large processed elements, and removing the processed children of an element with many of them. Both are in the "Pull API for non-blocking parsing" section, because this applies to
XMLPullParseras well.They are not universal, they only give an idea; the note ends with the way to avoid the tree entirely, an
XMLParserwith a custom target.iterparse#93618