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From "Eric Yang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CHUKWA-593) Archive daemon: infinite loop at midnight
Date Tue, 28 Jun 2011 22:43:29 GMT

    [ https://issues.apache.org/jira/browse/CHUKWA-593?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13056834#comment-13056834
] 

Eric Yang commented on CHUKWA-593:
----------------------------------

processDay function should delete the previous day directory, if the previous day directory
is empty.  The hour between 2 days, the system is design to archive for previous day as soon
as possible

Do you have collectors running in multiple timezones, or server clock is out of sync by one
hour?

The busy loop should not happen unless there something continue to write to the previous day
directory.  daysInRawArchiveDir.length==1 is to ensure the roll up for previous day happens
as soon as possible.

If we change to >=1 then the roll up for previous day will not occur until 1:59AM of the
current day.  We should avoid this latency, if possible.

> Archive daemon: infinite loop at midnight
> -----------------------------------------
>
>                 Key: CHUKWA-593
>                 URL: https://issues.apache.org/jira/browse/CHUKWA-593
>             Project: Chukwa
>          Issue Type: Bug
>          Components: MR Data Processors
>    Affects Versions: 0.4.0
>         Environment: Debian 5.0, Hadoop 0.20
>            Reporter: Sourygna Luangsay
>            Priority: Minor
>             Fix For: 0.4.0, 0.5.0
>
>   Original Estimate: 10m
>  Remaining Estimate: 10m
>
> The archive manager Chukwa daemon enters an infinite loop between 24H to 1H. This entails
an increase of the namenode load and a huge increase of both chukwa and namenode logs.
> Problem seems to come from the start function of ChukwaArchiveManager.java (in package
org/apache/hadoop/chukwa/extraction/archive). At midnight, we get two directories in /chukwa/dataSinkArchives/
(one for the last day and one for the new day). This means that we neither enter the "daysInRawArchiveDir.length
== 0" condition nor the "daysInRawArchiveDir.length == 1" one. processDay function is then
called but few is done due to "modificationDate < oneHourAgo" condition.
> Finally, we loop without having slept or deleted last day directory. Such process repeats
itself during one hour.
> Here is how I propose to change the "daysInRawArchiveDir.length == 1" condition block
in the start function:
> 148         if (daysInRawArchiveDir.length >= 1 ) {
> 149           long nextRun = lastRun + (2*ONE_HOUR) - (1*60*1000);// 2h -1min
> 150           if (now < nextRun) {
> 151             log.info("lastRun < 2 hours so skip archive for now, going to sleep
for 30 minutes, currentDate is:" + new java.util.Date());
> 152             Thread.sleep(30 * 60 * 1000);
> 153             continue;
> 154           }
> 155         }
> As for me, it removed the infinite loop problem. But maybe there is a reason to separate
"1 directory" case from "many directories" case. I've been reading documentation and subversion
but could not find it.
> If there is one, could someone explain it to me?
> Regards.

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