Discard documents to reclaim resources #14262
Labels
A-constellation
Involves the constellation
A-content/script
Related to the script thread
I-memory-leak
A memory leak has been observed.
Comments
asajeffrey
added
A-constellation
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In https://html.spec.whatwg.org/multipage/#garbage-collection-and-browsing-contexts:discard-a-document:
so if any pipeline P1 in a script thread contains a pointer to a DOM node from another pipeline P2 in the same script thread, then that DOM node will keep P2's AFAICT, this either means we need to hook into the SM gc to work out when we can reclaim documents, or we need to discard an entire script thread at a time. |
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IRC conversation with @nox: http://logs.glob.uno/?c=mozilla%23servo&s=17+Nov+2016&e=17+Nov+2016#c563837 TL;DR we can make Document WeakReferenceable, and use that to hook into the gc. |
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My first shot at it: master...asajeffrey:constellation-script-discard-documents (not actually tested yet). |
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Hmm, just making |
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IRC conversation with @nox: http://logs.glob.uno/?c=mozilla%23servo&s=18+Nov+2016&e=18+Nov+2016#c564456 TL;DR: expando objects can't be weak referenceable atm. |
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I rewrote my implementation for this, it now just keeps track of discarded documents in script, the constellation is unchanged: https://github.com/asajeffrey/servo/commits/script-discard-documents |
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bors-servo
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Dec 16, 2016
Implement discarding Document objects to reclaim space. <!-- Please describe your changes on the following line: --> This PR implements document discarding. Active documents are kept alive strongly, but inactive documents are only kept alive weakly. When a document is GCd, it is marked as discarded, and if it is every reactivated, a reload of the URL is triggered. Note that this PR is pretty aggressive about discarding, and can any inactive document (other than those being kept alive by other same-origin pipelines). We might want to damp it down a bit. Also note that this interacts with browser.html in that the reloading triggered by reactivating a document triggers mozbrowser events. To test this, I added a `-Zdiscard-inactive-documents` debug flag, which discards all inactive documents, even ones which are reachable through other same-origin pipelines. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [X] `./mach build -d` does not report any errors - [X] `./mach test-tidy` does not report any errors - [X] These changes fix #14262. - [X] These changes do not require tests because we should be able to use the existing tests with `-Zdiscard-inactive-documents`. <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> <!-- Reviewable:start --> --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14312) <!-- Reviewable:end -->
bors-servo
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Dec 16, 2016
Implement discarding Document objects to reclaim space. <!-- Please describe your changes on the following line: --> This PR implements document discarding. Active documents are kept alive strongly, but inactive documents are only kept alive weakly. When a document is GCd, it is marked as discarded, and if it is every reactivated, a reload of the URL is triggered. Note that this PR is pretty aggressive about discarding, and can any inactive document (other than those being kept alive by other same-origin pipelines). We might want to damp it down a bit. Also note that this interacts with browser.html in that the reloading triggered by reactivating a document triggers mozbrowser events. To test this, I added a `-Zdiscard-inactive-documents` debug flag, which discards all inactive documents, even ones which are reachable through other same-origin pipelines. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [X] `./mach build -d` does not report any errors - [X] `./mach test-tidy` does not report any errors - [X] These changes fix #14262. - [X] These changes do not require tests because we should be able to use the existing tests with `-Zdiscard-inactive-documents`. <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> <!-- Reviewable:start --> --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14312) <!-- Reviewable:end -->
bors-servo
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Dec 18, 2016
Implement discarding Document objects to reclaim space. <!-- Please describe your changes on the following line: --> This PR implements document discarding. Active documents are kept alive strongly, but inactive documents are only kept alive weakly. When a document is GCd, it is marked as discarded, and if it is every reactivated, a reload of the URL is triggered. Note that this PR is pretty aggressive about discarding, and can any inactive document (other than those being kept alive by other same-origin pipelines). We might want to damp it down a bit. Also note that this interacts with browser.html in that the reloading triggered by reactivating a document triggers mozbrowser events. To test this, I added a `-Zdiscard-inactive-documents` debug flag, which discards all inactive documents, even ones which are reachable through other same-origin pipelines. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [X] `./mach build -d` does not report any errors - [X] `./mach test-tidy` does not report any errors - [X] These changes fix #14262. - [X] These changes do not require tests because we should be able to use the existing tests with `-Zdiscard-inactive-documents`. <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> <!-- Reviewable:start --> --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14312) <!-- Reviewable:end -->
bors-servo
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Implement discarding Document objects to reclaim space. <!-- Please describe your changes on the following line: --> This PR implements document discarding. Active documents are kept alive strongly, but inactive documents are only kept alive weakly. When a document is GCd, it is marked as discarded, and if it is every reactivated, a reload of the URL is triggered. Note that this PR is pretty aggressive about discarding, and can any inactive document (other than those being kept alive by other same-origin pipelines). We might want to damp it down a bit. Also note that this interacts with browser.html in that the reloading triggered by reactivating a document triggers mozbrowser events. To test this, I added a `-Zdiscard-inactive-documents` debug flag, which discards all inactive documents, even ones which are reachable through other same-origin pipelines. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [X] `./mach build -d` does not report any errors - [X] `./mach test-tidy` does not report any errors - [X] These changes fix #14262. - [X] These changes do not require tests because we should be able to use the existing tests with `-Zdiscard-inactive-documents`. <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> <!-- Reviewable:start --> --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14312) <!-- Reviewable:end -->
bors-servo
pushed a commit
that referenced
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Jan 4, 2017
Implement discarding Document objects to reclaim space. <!-- Please describe your changes on the following line: --> This PR implements document discarding. Active documents are kept alive strongly, but inactive documents are only kept alive weakly. When a document is GCd, it is marked as discarded, and if it is every reactivated, a reload of the URL is triggered. Note that this PR is pretty aggressive about discarding, and can any inactive document (other than those being kept alive by other same-origin pipelines). We might want to damp it down a bit. Also note that this interacts with browser.html in that the reloading triggered by reactivating a document triggers mozbrowser events. To test this, I added a `-Zdiscard-inactive-documents` debug flag, which discards all inactive documents, even ones which are reachable through other same-origin pipelines. --- <!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: --> - [X] `./mach build -d` does not report any errors - [X] `./mach test-tidy` does not report any errors - [X] These changes fix #14262. - [X] These changes do not require tests because we should be able to use the existing tests with `-Zdiscard-inactive-documents`. <!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. --> <!-- Reviewable:start --> --- This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/14312) <!-- Reviewable:end -->
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The HTML spec allows documents to be discarded to reclaim resources (https://html.spec.whatwg.org/multipage/#discard-a-document). In particular, documents that aren't active may be discarded (https://html.spec.whatwg.org/multipage/browsers.html#the-session-history-of-browsing-contexts:discard-a-document).
#11893 contains a partial implementation.
cc @Ms2ger @jdm @ConnorGBrewster @metajack
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