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https://issues.apache.org/jira/browse/UNOMI-748?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17699002#comment-17699002
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Kevan Jahanshahi commented on UNOMI-748:
----------------------------------------
Other impacted area:
[https://github.com/apache/unomi/blob/master/extensions/lists-extension/services/src/main/java/org/apache/unomi/services/UserListServiceImpl.java#L88-L97]
loading all profiles in RAM:
{code:java}
List<Profile> profiles = persistenceService.query(query, null,
Profile.class);{code}
{{{}{}}}Do asynchronous update using bulkProcessor:
{{}}
{code:java}
{code}
{{persistenceService.update(p, Profile.class, "systemProperties",
profileSystemProperties);}}
{{{}{}}}It’s actually really dangerous, because the bulk processor is retaining
the action, so the profile could be added to a user list in the mean time.
And once the bulk processor would execute it’s retain action, the profile
system properties will be overwritten.
2 risks identified here:
* OOM: in case a lot of profiles in the user list
* inconsistency due to asynchronous bulkprocessor overwritting the profiles
systemProperties
> Unomi merge system is exposed to OOM
> ------------------------------------
>
> Key: UNOMI-748
> URL: https://issues.apache.org/jira/browse/UNOMI-748
> Project: Apache Unomi
> Issue Type: Improvement
> Affects Versions: unomi-2.1.0
> Reporter: Kevan Jahanshahi
> Priority: Major
>
> currently the sessions/events *update* is using bulkProcessor and it is
> asynchronous, we never know when the bulk will be perform.
> * t{+}he benefit{+}: fast merge requests, the merge request is fast as
> nothing is retain, bulk processor will do the job in a separate thread.
> * {+}the cons{+}: {*}all previous sessions/events are first loaded in
> memory{*}, so in case of merging active profiles that contains a lot of past
> events/sessions, {{{}we could be exposed to OOM{}}}. {_}(We already had
> similar case with the purge that was loading all profiles in memory.{_})
> If we replace the *update(one item at a time)* by using {*}updateByQuery{*},
> the request will loose it’s asynchronous nature provided by the so called:
> BulkProcessor.
> * {+}the benefit{+}: sessions, events not load in memory, no OOM possible
> * {+}the cons{+}: request will be synchron and {{{}we expose merge requests
> to timeout on client side{}}}. merge is actually trigger by the login on jExp
> side adding extra timing here could have bad impacts and side effects.
>
> Since none of this solution seem’s ok, the perfect solution should be a mix
> of both strength: * use *{{updateByQuery}}* in a separate thread to avoid
> retaining merge request
> *
> ** We have the OOM protection by not loading all the past events/sessions
> ** We have the asynchronous execution done in a separate thread/job to free
> the current request.
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