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https://issues.apache.org/jira/browse/HDFS-14346?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16791016#comment-16791016
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Erik Krogen commented on HDFS-14346:
------------------------------------
Thanks [~csun], makes sense. I gave the patch a thorough review and you have a
+1 from me. My only small concern -- should the new {{getTimeDurationHelper()}}
be {{private}}? {{Configuration}} is a very public interface and it seems
better not to expose it if we don't have to.
> Better time precision in getTimeDuration
> ----------------------------------------
>
> Key: HDFS-14346
> URL: https://issues.apache.org/jira/browse/HDFS-14346
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Chao Sun
> Assignee: Chao Sun
> Priority: Minor
> Attachments: HDFS-14346.000.patch
>
>
> Currently, {{Configuration#getTimeDuration}} has the following signature:
> {code}
> /**
> * Return time duration in the given time unit. Valid units are encoded in
> * properties as suffixes: nanoseconds (ns), microseconds (us), milliseconds
> * (ms), seconds (s), minutes (m), hours (h), and days (d).
> * @param name Property name
> * @param defaultValue Value returned if no mapping exists.
> * @param unit Unit to convert the stored property, if it exists.
> * @throws NumberFormatException If the property stripped of its unit is not
> * a number
> */
> public long getTimeDuration(String name, long defaultValue, TimeUnit unit)
> {code}
> This may lose precision in case the default time unit is larger than the time
> unit that the configuration value is converted to in the call sites of this
> method. For instance, in {{EditLogTailer}} this method is used in the
> following manner:
> {code}
> logRollPeriodMs = conf.getTimeDuration(
> DFSConfigKeys.DFS_HA_LOGROLL_PERIOD_KEY,
> DFSConfigKeys.DFS_HA_LOGROLL_PERIOD_DEFAULT, TimeUnit.SECONDS) * 1000;
> sleepTimeMs = conf.getTimeDuration(
> DFSConfigKeys.DFS_HA_TAILEDITS_PERIOD_KEY,
> DFSConfigKeys.DFS_HA_TAILEDITS_PERIOD_DEFAULT, TimeUnit.SECONDS) *
> 1000;
> {code}
> in both cases, the default time unit is second, and the configuration value
> is converted into milli-seconds. Precision is lost when people want to
> specify sub-second time duration such as {{100ms}}, which will be converted
> to {{0ms}}.
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