bigreybear opened a new pull request, #11985:
URL: https://github.com/apache/iotdb/pull/11985
## Description
The recent deadlock issues are primarily attributed to the double-bucket
index design. Each thread maintains a local collection that organizes pages
into buckets based on available space, while the PageManager maintains another
gloabl set. When a write thread requires a page for writing/updating, it first
checks its local buckets and retrieves pages without locking(as they are
already locked). If no suitable page is found locally, the thread then accesses
the global buckets, where it must retrieve pages with a lock.
The issue arises when a page, which is appropriate for the expected size and
referred by the thread previously, is recorded in the global buckets but not in
the local ones. This results in the page being locked twice but unlocked only
once, leading to a deadlock. Specifically, if a page increases its available
space but is not checked and registered in the local buckets, a deadlock
becomes highly probable.
This revision made a comprehensive review of any modifications made to the
SchemaPage.spareSize field, which determines the page's suitability for the
expected space. All methods that modify this attribute are listed below.
Additionally, these methods are now accompanied by statements for recording
them in the appropriate buckets
SegmentedPage spare size write-value occurence
1. deleteSegment (handled by previous PR)
2. purgeSegment (handled by previous PR)
3. relocateSegment
called by:
3.1 SegmentedPage.write // covered when write within PageManager
3.2 SegmentedPage.update // covered when update within PageManager
4. reaarangeSegment
called by:
4.1 relocateSegment, trace to 3.
4.2 compactSegment // covered
compactSegment called by
4.2.1 allocNewSegment, only called by pre-allocate, now covered
with bucket sort
4.2.2 transplantSegment // covered previously
5. extendSegmentInPlace // only extend last segment so only decrease spare
size
6. registerNewSegment // only decrease
Furthermore, this PR also refactore SegmentedPage.write/update inteface so
that overflow will return a negative value rather than an exception.
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<hr>
This PR has:
- [ ] been self-reviewed.
- [ ] concurrent read
- [ ] concurrent write
- [ ] concurrent read and write
- [ ] added documentation for new or modified features or behaviors.
- [ ] added Javadocs for most classes and all non-trivial methods.
- [ ] added or updated version, __license__, or notice information
- [ ] added comments explaining the "why" and the intent of the code
wherever would not be obvious
for an unfamiliar reader.
- [ ] added unit tests or modified existing tests to cover new code paths,
ensuring the threshold
for code coverage.
- [ ] added integration tests.
- [ ] been tested in a test IoTDB cluster.
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<hr>
##### Key changed/added classes (or packages if there are too many classes)
in this PR
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