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https://issues.apache.org/jira/browse/OLINGO-1625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17862451#comment-17862451
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Ron Passerini commented on OLINGO-1625:
---------------------------------------
I think I've followed the correct guidelines for getting a patch submitted for
consideration using the Jira/Patch method describe here - [Apache Olingo
Library|https://olingo.apache.org/contribute.html#contribute-via-git-patchpull-request-and-olingo-jira]
If there is something I have missed, could you let me know? I assumed I would
have heard something back about this by now.
> The serializers have performance issues when Entities contain very large
> numbers of Properties
> ----------------------------------------------------------------------------------------------
>
> Key: OLINGO-1625
> URL: https://issues.apache.org/jira/browse/OLINGO-1625
> Project: Olingo
> Issue Type: Bug
> Components: odata4-server
> Affects Versions: Version (Java) V4 5.0.0
> Reporter: Ron Passerini
> Priority: Major
> Labels: json, performance, serialization, xml
> Fix For: (Java) V4 5.0.1
>
> Attachments:
> 0001-OLINGO-1625-Fix-performance-problem-in-serializers-f.patch
>
>
> I've implemented an OData service that serves up some large datasets in a
> streaming fashion. Some of those datasets have large numbers of fields (over
> 1,000). When I requested one of them which was around 350M in size, it took
> way longer than expected.
> I profiled the request in IntelliJ's profiler and found that over 75% of the
> CPU cycles were spent in String.equals() comparing column names in the
> serializers. This is because there is an O(N^2) issue that for every column
> selected (in my case all of them) it will iterate across the entire list of
> entity properties looking for the one with the same name.
> I have already implemented a fix whereby before doing the property
> serialization, the serializer builds a hash map of property-name-to-property,
> making the resulting algorithm O(N) with the number of properties being
> serialized.
> After profiling the change, again in IntelliJ's profiler, the String.equals()
> which was over 75% before, is now under 1%.
> I will be creating a patch and attaching it momentarily.
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