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https://issues.apache.org/jira/browse/HDFS-10560?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15345518#comment-15345518
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Anu Engineer commented on HDFS-10560:
-------------------------------------
[~linyiqun] Thank you for finding this issue and providing a fix for the issue.
Overall the patch looks very good. I had some minor comments.
I see that sometimes we use
{code:title=DiskBalancerWorkItem.java|borderStyle=solid}
return MAPPER.writeValueAsString(this);
{code}
but in other places we use
{code:title=DiskBalancer.java|borderStyle=solid}
return JsonUtil.toJsonString(pathMap);
{code}
If this is not intentional can we please use a consistent way of doing it. I
don't have any preference, either way is fine.
{{DiskBalancerWorkStatus.java#currentStateString}} Since we enable
INDENT_OUTPUT here, was wondering is that going to carry over to
{{toJsonString}}. Not that it is an error or anything, just making sure that
side-effect is intentional.
{{CombinedHostsFileReader.java}} and {{CombinedHostsFileWriter.java}} are not
part of diskbalancer. Should we clean up those files in another JIRA ?
> DiskBalancer: Reuse ObjectMapper instance to improve the performance
> --------------------------------------------------------------------
>
> Key: HDFS-10560
> URL: https://issues.apache.org/jira/browse/HDFS-10560
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: balancer & mover
> Affects Versions: HDFS-1312
> Reporter: Yiqun Lin
> Assignee: Yiqun Lin
> Attachments: HDFS-10560-HDFS-1312.001.patch,
> HDFS-10560-HDFS-1312.002.patch
>
>
> In branch HDFS-1312, there are many places use {{ObjectMapper}} instances to
> do the json-object transform. But {{ObjectMapper}} instance is relatively
> heavy, we should reuse them as possible. And In addition, {{ObjectMapper}} is
> thread safe, can see this link:http://wiki.fasterxml.com/JacksonFAQ.
> Here are related issues: HDFS-9724, HDFS-9768. We can see detail info in this
> issues.
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