Fixed 2 issues: Memory resource not released and flushing of non-dirty pages #24
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lamduynguyen
reviewed
Oct 3, 2024
| @@ -51,6 +51,7 @@ class CRManager | |||
| ~CRManager(); | |||
| // ------------------------------------------------------------------------------------- | |||
| void registerMeAsSpecialWorker(); | |||
| void deleteSpecialWorker(); | |||
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Why do you need this?
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The memory for the special worker is not released. It does not pass address sanitizer.
| @@ -81,7 +81,10 @@ struct BufferFrame { | |||
| // ------------------------------------------------------------------------------------- | |||
| bool operator==(const BufferFrame& other) { return this == &other; } | |||
| // ------------------------------------------------------------------------------------- | |||
| inline bool isDirty() const { return page.PLSN != header.last_written_plsn; } | |||
| inline bool isDirty() const { return | |||
| page.PLSN != 0 && // marked as dirty | |||
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PLSN will increase monotonically and will be increased here:
https://github.com/leanstore/leanstore/blob/master/backend/leanstore/sync-primitives/PageGuard.hpp#L122C1-L127C23
That means, your first condition is inclusive with page.PLSN != header.last_written_plsn
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If the page is only read but not written, it should not be flushed. My experiments also see write volume for read-only workload.
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Fixed 2 issues:
BufferFrame::isDirty()flushes page withPLSN == 0, which are not modified, I believe. With the original code, experiments recovered from existing DB with read-only TXs witness page writes consistently above zero.The fixed code passes multiple runs of various experiments, including persisting and recovering (& verifying). But I would still appreciate a set of fresh eyes, especially because the changes are cherrypicked from my branch.