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https://issues.apache.org/jira/browse/HDFS-14317?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16780997#comment-16780997
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Ekanth Sethuramalingam commented on HDFS-14317:
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Thanks for the review Erik.
{quote} * The active parameter to waitForStandbyToCatchUpWithInProgressEdits()
is not used.{quote}
Good catch. Will do.
{quote} * The until parameters could use a more descriptive name, like
maxWaitSec{quote}
Will do.
{quote} * Why do we need to test with both nn0 and nn1 as active? Is there a
difference between these two situations?{quote}
I thought about it but followed the other test which circles between the
namenodes. I am not sure if I'll be missing something by not doing it. I'll
remove this for now.
{quote} * It seems like there's a pretty long wait time involved. If we make
the edit tail period to something like 10ms, can we reduce the wait
times?{quote}
I did think about this. Unfortunately, {{dfs.ha.tail-edits.period}} and
{{dfs.ha.log-roll.period}} are both in seconds.
{quote} * For the checkForLogRoll call on L406, it seems like waitFor() is a
bit overkill here. Can't we just sleep for 2s and then check if it has
changed?{quote}
This allows for reuse, consistency (with other waits in the test class) and
fast fail. Also, I don't see this to be a huge cost to optimize for here. I can
change it if you feel strongly about this.
> Standby does not trigger edit log rolling when in-progress edit log tailing
> is enabled
> --------------------------------------------------------------------------------------
>
> Key: HDFS-14317
> URL: https://issues.apache.org/jira/browse/HDFS-14317
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.9.0, 3.0.0
> Reporter: Ekanth Sethuramalingam
> Assignee: Ekanth Sethuramalingam
> Priority: Critical
> Attachments: HDFS-14317.001.patch
>
>
> The standby uses the following method to check if it is time to trigger edit
> log rolling on active.
> {code}
> /**
> * @return true if the configured log roll period has elapsed.
> */
> private boolean tooLongSinceLastLoad() {
> return logRollPeriodMs >= 0 &&
> (monotonicNow() - lastLoadTimeMs) > logRollPeriodMs ;
> }
> {code}
> In doTailEdits(), lastLoadTimeMs is updated when standby is able to
> successfully tail any edits
> {code}
> if (editsLoaded > 0) {
> lastLoadTimeMs = monotonicNow();
> }
> {code}
> The default configuration for {{dfs.ha.log-roll.period}} is 120 seconds and
> {{dfs.ha.tail-edits.period}} is 60 seconds. With in-progress edit log tailing
> enabled, tooLongSinceLastLoad() will almost never return true resulting in
> edit logs not rolled for a long time until this configuration
> {{dfs.namenode.edit.log.autoroll.multiplier.threshold}} takes effect.
> [In our deployment, this resulted in in-progress edit logs getting deleted.
> The sequence of events is that standby was able to checkpoint twice while the
> in-progress edit log was growing on active. When the
> NNStorageRetentionManager decided to cleanup old checkpoints and edit logs,
> it cleaned up the in-progress edit log from active and QJM (as the txnid on
> in-progress edit log was older than the 2 most recent checkpoints) resulting
> in irrecoverably losing a few minutes worth of metadata].
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