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https://issues.apache.org/jira/browse/IGNITE-14341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17539666#comment-17539666
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Pavel Pereslegin commented on IGNITE-14341:
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Currently to clean up expired entries we are getting the cursor and deleting
rows one by one.
Thus, for each row, we perform a search from the root, lock the page for
writing, and delete single row.
!expire1.png!
Instead of deleting a single row, we can delete all rows from a specified range
on the page.
This reduces the number of page write locks.
!expire2.png!
> Reduce contention in the PendingEntriesTree when cleaning up expired entries.
> -----------------------------------------------------------------------------
>
> Key: IGNITE-14341
> URL: https://issues.apache.org/jira/browse/IGNITE-14341
> Project: Ignite
> Issue Type: Improvement
> Reporter: Aleksey Plekhanov
> Assignee: Pavel Pereslegin
> Priority: Major
> Labels: ise
> Attachments: JmhCacheExpireBenchmark.java, expire1.png, expire2.png
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, there is a significant performance drop when expired entries
> concurrently evicted by threads that perform some actions with cache (see
> attached reproducer):
> {noformat}
> Benchmark Mode Cnt Score Error
> Units
> JmhCacheExpireBenchmark.putWithExpire thrpt 3 100,132 ± 21,025
> ops/ms
> JmhCacheExpireBenchmark.putWithoutExpire thrpt 3 2133,122 ± 559,694
> ops/ms{noformat}
> Root cause: pending entries tree (offheap BPlusTree) is used to track expired
> entries, after each cache operation (and by timeout thread) there is an
> attempt to evict some amount of expired entries. these entries looked up from
> the start of the pending entries tree and there is a contention on the first
> leaf page of that tree.
> All threads waiting for the same page lock:
> {noformat}
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
> at
> org.apache.ignite.internal.util.OffheapReadWriteLock.waitAcquireWriteLock(OffheapReadWriteLock.java:503)
> at
> org.apache.ignite.internal.util.OffheapReadWriteLock.writeLock(OffheapReadWriteLock.java:244)
> at
> org.apache.ignite.internal.pagemem.impl.PageMemoryNoStoreImpl.writeLock(PageMemoryNoStoreImpl.java:528)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.util.PageHandler.writeLock(PageHandler.java:422)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.util.PageHandler.writePage(PageHandler.java:350)
> at
> org.apache.ignite.internal.processors.cache.persistence.DataStructure.write(DataStructure.java:325)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree.access$13200(BPlusTree.java:100)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree$Remove.doRemoveFromLeaf(BPlusTree.java:4588)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree$Remove.removeFromLeaf(BPlusTree.java:4567)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree$Remove.tryRemoveFromLeaf(BPlusTree.java:5196)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree$Remove.access$6800(BPlusTree.java:4209)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree.removeDown(BPlusTree.java:2189)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree.removeDown(BPlusTree.java:2165)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree.removeDown(BPlusTree.java:2165)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree.doRemove(BPlusTree.java:2076)
> at
> org.apache.ignite.internal.processors.cache.persistence.tree.BPlusTree.removex(BPlusTree.java:1905)
> at
> org.apache.ignite.internal.processors.cache.IgniteCacheOffheapManagerImpl.expireInternal(IgniteCacheOffheapManagerImpl.java:1426)
> at
> org.apache.ignite.internal.processors.cache.IgniteCacheOffheapManagerImpl.expire(IgniteCacheOffheapManagerImpl.java:1375)
> at
> org.apache.ignite.internal.processors.cache.GridCacheTtlManager.expire(GridCacheTtlManager.java:246)
> at
> org.apache.ignite.internal.processors.cache.GridCacheUtils.unwindEvicts(GridCacheUtils.java:882){noformat}
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