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https://issues.apache.org/jira/browse/HDFS-1572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12980404#action_12980404
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Jakob Homan commented on HDFS-1572:
-----------------------------------
The getJournalSize() rpc is only called once every five minutes to check if the
journal size is too big. The 60 seconds is just to check if that call needs to
be made, or if the duration-based checkpointing should be done. The 60 seconds
improves the granularity of the duration. Currently it's duration+5 minutes at
a maximum. This moves it to duration+1 minute at a maximum. The same number
of RPC calls are being made since the getJournalSize() branch is only traversed
every 5 minutes. It is true that if the period has expired (once an hour by
default, once a day on all production systems I've seen), we'd do a single
extra RPC call. I think this is worth it to improve code clarity.
> Checkpointer should trigger checkpoint with specified period.
> -------------------------------------------------------------
>
> Key: HDFS-1572
> URL: https://issues.apache.org/jira/browse/HDFS-1572
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 0.22.0
> Reporter: Liyin Liang
> Priority: Blocker
> Fix For: 0.21.0
>
> Attachments: 1527-1.diff, 1572-2.diff, HDFS-1572-2.patch,
> HDFS-1572.patch
>
>
> {code:}
> long now = now();
> boolean shouldCheckpoint = false;
> if(now >= lastCheckpointTime + periodMSec) {
> shouldCheckpoint = true;
> } else {
> long size = getJournalSize();
> if(size >= checkpointSize)
> shouldCheckpoint = true;
> }
> {code}
> {dfs.namenode.checkpoint.period} in configuration determines the period of
> checkpoint. However, with above code, the Checkpointer triggers a checkpoint
> every 5 minutes (periodMSec=5*60*1000). According to SecondaryNameNode.java,
> the first *if* statement should be:
> {code:}
> if(now >= lastCheckpointTime + 1000 * checkpointPeriod) {
> {code}
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