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https://issues.apache.org/jira/browse/OAK-3976?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stefan Egli updated OAK-3976:
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Description:
Journal entries are created in the background write. Normally this happens
every second. If for some reason there is a large delay between two background
writes, the number of pending changes can also accumulate. Which can result in
(arbitrary) large single journal entries (ie with large {{_c}} property).
This can cause multiple problems down the road:
* journal gc at this point loads 450 entries - and if some are large this can
result in a very large memory consumption during gc (which can cause severe
stability problems for the VM, if not OOM etc). This should be fixed with
OAK-3001 (where we only get the id, thus do not care how big {{_c}} is)
* before OAK-3001 is done (which is currently scheduled after 1.4) what we can
do is reduce the delete batch size (OAK-3975)
* background reads however also read the journal entries and even if
OAK-3001/OAK-3975 are implemented the background read can still cause large
memory consumption. So we need to improve this one way or another.
was:
Journal entries are created in the background write. Normally this happens
every second. If for some reason there is a large delay between two background
writes, the number of journal entries can also accumulate. Which can result in
(arbitrary) large single journal entries (ie with large {{_c}} property).
This can cause multiple problems down the road:
* journal gc at this point loads 450 entries - and if some are large this can
result in a very large memory consumption during gc (which can cause severe
stability problems for the VM, if not OOM etc). This should be fixed with
OAK-3001 (where we only get the id, thus do not care how big {{_c}} is)
* before OAK-3001 is done (which is currently scheduled after 1.4) what we can
do is reduce the delete batch size (OAK-3975)
* background reads however also read the journal entries and even if
OAK-3001/OAK-3975 are implemented the background read can still cause large
memory consumption. So we need to improve this one way or another.
> journal should support large(r) entries
> ---------------------------------------
>
> Key: OAK-3976
> URL: https://issues.apache.org/jira/browse/OAK-3976
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: documentmk
> Affects Versions: 1.3.14
> Reporter: Stefan Egli
> Fix For: 1.6
>
>
> Journal entries are created in the background write. Normally this happens
> every second. If for some reason there is a large delay between two
> background writes, the number of pending changes can also accumulate. Which
> can result in (arbitrary) large single journal entries (ie with large {{_c}}
> property).
> This can cause multiple problems down the road:
> * journal gc at this point loads 450 entries - and if some are large this can
> result in a very large memory consumption during gc (which can cause severe
> stability problems for the VM, if not OOM etc). This should be fixed with
> OAK-3001 (where we only get the id, thus do not care how big {{_c}} is)
> * before OAK-3001 is done (which is currently scheduled after 1.4) what we
> can do is reduce the delete batch size (OAK-3975)
> * background reads however also read the journal entries and even if
> OAK-3001/OAK-3975 are implemented the background read can still cause large
> memory consumption. So we need to improve this one way or another.
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