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https://issues.apache.org/jira/browse/CARBONDATA-484?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jihong MA updated CARBONDATA-484:
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Description:
LRU Cache for B-Tree is proposed to ensure to avoid out memory, when too many
number of tables exits and all are not frequently used.
Problem:
CarbonData is maintaining two level of B-Tree cache, one at the driver level
and another at executor level. Currently CarbonData has the mechanism to
invalidate the segments and blocks cache for the invalid table segments, but
there is no eviction policy for the unused cached object. So the instance at
which complete memory is utilized then the system will not be able to process
any new requests.
Solution:
In the cache maintained at the driver level and at the executor there must be
objects in cache currently not in use. Therefore system should have the
mechanism to below mechanism.
1. Set the max memory limit till which objects could be hold in the
memory.
2. When configured memory limit reached then identify the cached objects
currently not in use so that the required memory could be freed without
impacting the existing process.
3. Eviction should be done only till the required memory is not meet.
For details please refer to attachments.
was:
*LRU Cache for B-Tree*
Problem:
CarbonData is maintaining two level of B-Tree cache, one at the driver level
and another at executor level. Currently CarbonData has the mechanism to
invalidate the segments and blocks cache for the invalid table segments, but
there is no eviction policy for the unused cached object. So the instance at
which complete memory is utilized then the system will not be able to process
any new requests.
Solution:
In the cache maintained at the driver level and at the executor there must be
objects in cache currently not in use. Therefore system should have the
mechanism to below mechanism.
1. Set the max memory limit till which objects could be hold in the
memory.
2. When configured memory limit reached then identify the cached objects
currently not in use so that the required memory could be freed without
impacting the existing process.
3. Eviction should be done only till the required memory is not meet.
For details please refer to attachments.
Summary: Implement LRU cache for B-Tree (was: Implement LRU cache for
B-Tree to ensure to avoid out memory, when too many number of tables exits and
all are not frequently used.)
> Implement LRU cache for B-Tree
> ---
>
> Key: CARBONDATA-484
> URL: https://issues.apache.org/jira/browse/CARBONDATA-484
> Project: CarbonData
> Issue Type: New Feature
>Reporter: Mohammad Shahid Khan
>Assignee: Mohammad Shahid Khan
> Attachments: B-Tree LRU Cache.pdf
>
>
> LRU Cache for B-Tree is proposed to ensure to avoid out memory, when too
> many number of tables exits and all are not frequently used.
> Problem:
> CarbonData is maintaining two level of B-Tree cache, one at the driver level
> and another at executor level. Currently CarbonData has the mechanism to
> invalidate the segments and blocks cache for the invalid table segments, but
> there is no eviction policy for the unused cached object. So the instance at
> which complete memory is utilized then the system will not be able to process
> any new requests.
> Solution:
> In the cache maintained at the driver level and at the executor there must be
> objects in cache currently not in use. Therefore system should have the
> mechanism to below mechanism.
> 1. Set the max memory limit till which objects could be hold in the
> memory.
> 2. When configured memory limit reached then identify the cached
> objects currently not in use so that the required memory could be freed
> without impacting the existing process.
> 3. Eviction should be done only till the required memory is not meet.
> For details please refer to attachments.
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