Broker cache eviction evicts entries that haven't been read by active consumers #16054
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@315157973 @lordcheng10 @merlimat @codelipenghui What's your thoughts on this issue? I wonder if the need for #14985 was caused by the regression described in this issue? |
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@315157973 @lordcheng10 @merlimat @codelipenghui please take a look at this issue since it seems that the broker cache is broken atm. |
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this is partially related |
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lhotari
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Aug 23, 2022
…on of active cursors when cacheEvictionByMarkDeletedPosition=false Fixes apache#16054 - calculate the sorted list of when a read position gets updated - this resolves apache#9958 in a proper way - apache#12045 broke the caching solution as explained in apache#16054
lhotari
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Aug 25, 2022
… active cursors when cacheEvictionByMarkDeletedPosition=false Fixes apache#16054 - calculate the sorted list of when a read position gets updated - this resolves apache#9958 in a proper way - apache#12045 broke the caching solution as explained in apache#16054 - remove invalid tests - fix tests - add more tests to handle corner cases
lhotari
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Aug 26, 2022
… active cursors when cacheEvictionByMarkDeletedPosition=false Fixes apache#16054 - calculate the sorted list of when a read position gets updated - this resolves apache#9958 in a proper way - apache#12045 broke the caching solution as explained in apache#16054 - remove invalid tests - fix tests - add more tests to handle corner cases
lhotari
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Aug 31, 2022
…sors (#17273) * [fix][broker] Fix broken build caused by conflict between #17195 and #16605 - #17195 changed the method signature that #16605 depended upon * [fix][broker] Keep sorted list of cursors ordered by read position of active cursors when cacheEvictionByMarkDeletedPosition=false Fixes #16054 - calculate the sorted list of when a read position gets updated - this resolves #9958 in a proper way - #12045 broke the caching solution as explained in #16054 - remove invalid tests - fix tests - add more tests to handle corner cases * Address review comment * Handle durable & non-durable in the correct way * Fix cache tests since now entries get evicted reactively * Address review comment about method names * Change signature for add method so that position must be passed - this is more consistent with cursorUpdated method where the position is passed * Update javadoc for ManagedCursorContainer * Address review comment * Simplify ManagedCursorContainer * Clarify javadoc * Ensure that cursors are tracked by making sure that initial position isn't null unintentionally * Prevent race in updating activeCursors
Technoboy-
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Oct 31, 2022
…sors (#17273) * [fix][broker] Fix broken build caused by conflict between #17195 and #16605 - #17195 changed the method signature that #16605 depended upon * [fix][broker] Keep sorted list of cursors ordered by read position of active cursors when cacheEvictionByMarkDeletedPosition=false Fixes #16054 - calculate the sorted list of when a read position gets updated - this resolves #9958 in a proper way - #12045 broke the caching solution as explained in #16054 - remove invalid tests - fix tests - add more tests to handle corner cases * Address review comment * Handle durable & non-durable in the correct way * Fix cache tests since now entries get evicted reactively * Address review comment about method names * Change signature for add method so that position must be passed - this is more consistent with cursorUpdated method where the position is passed * Update javadoc for ManagedCursorContainer * Address review comment * Simplify ManagedCursorContainer * Clarify javadoc * Ensure that cursors are tracked by making sure that initial position isn't null unintentionally * Prevent race in updating activeCursors
congbobo184
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Nov 17, 2022
…sors (#17273) * [fix][broker] Fix broken build caused by conflict between #17195 and #16605 - #17195 changed the method signature that #16605 depended upon * [fix][broker] Keep sorted list of cursors ordered by read position of active cursors when cacheEvictionByMarkDeletedPosition=false Fixes #16054 - calculate the sorted list of when a read position gets updated - this resolves #9958 in a proper way - #12045 broke the caching solution as explained in #16054 - remove invalid tests - fix tests - add more tests to handle corner cases * Address review comment * Handle durable & non-durable in the correct way * Fix cache tests since now entries get evicted reactively * Address review comment about method names * Change signature for add method so that position must be passed - this is more consistent with cursorUpdated method where the position is passed * Update javadoc for ManagedCursorContainer * Address review comment * Simplify ManagedCursorContainer * Clarify javadoc * Ensure that cursors are tracked by making sure that initial position isn't null unintentionally * Prevent race in updating activeCursors (cherry picked from commit 856ef15)
congbobo184
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Dec 7, 2022
…sors (#17273) * [fix][broker] Fix broken build caused by conflict between #17195 and #16605 - #17195 changed the method signature that #16605 depended upon * [fix][broker] Keep sorted list of cursors ordered by read position of active cursors when cacheEvictionByMarkDeletedPosition=false Fixes #16054 - calculate the sorted list of when a read position gets updated - this resolves #9958 in a proper way - #12045 broke the caching solution as explained in #16054 - remove invalid tests - fix tests - add more tests to handle corner cases * Address review comment * Handle durable & non-durable in the correct way * Fix cache tests since now entries get evicted reactively * Address review comment about method names * Change signature for add method so that position must be passed - this is more consistent with cursorUpdated method where the position is passed * Update javadoc for ManagedCursorContainer * Address review comment * Simplify ManagedCursorContainer * Clarify javadoc * Ensure that cursors are tracked by making sure that initial position isn't null unintentionally * Prevent race in updating activeCursors (cherry picked from commit 856ef15)
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Describe the bug
There's a performance regression with large fan-outs (large number of consumers).
#12045 changed cache eviction. The problem is that cache eviction is done to the position whatever happens to be the first cursor in the "heap" list in ManagedCursorContainer. There's a chance for a race condition: another cursor in the list might have an older position, but that hasn't been updated in the ordered data structure ("heap") when the method is called. The cache eviction will take the read position directly from the first cursor and it ignores and older positions.
When the consumer for the other cursor does a read, the entries are no more in the cache and there will be a cache miss.
To Reproduce
It should be possible to reproduce this in a multi-consumer scenario where the speed of the consumers varies.
Expected behavior
Cache eviction should properly consider all active consumers. This was the state before #12045 and #14985 changes.
Additional context
#12045, #14985, #16049
This impacts all maintenance branches since #12045 was cherry-picked to branch-2.7 (2.7.4), branch-2.8 (2.8.2) and branch-2.9 (2.9.0) at the time.
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