[jira] [Created] (UIMA-5561) DUCC Web Server (WS) queries DB too often

["Lou DeGenaro (JIRA)" <de...@uima.apache.org>]

Lou DeGenaro created UIMA-5561:
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             Summary: DUCC Web Server (WS) queries DB too often
                 Key: UIMA-5561
                 URL: https://issues.apache.org/jira/browse/UIMA-5561
             Project: UIMA
          Issue Type: Bug
          Components: DUCC
            Reporter: Lou DeGenaro
            Assignee: Lou DeGenaro
             Fix For: 2.2.2-Ducc


In order for the WS to determine if the DB is up, it reads the checkpoint dataset.  However, this operation is performed for each individual user request for the daemons page.  If say Zabbix and others are making such requests this could amount to a plethora of reads of the checkpoint dataset.

Evidence is a slew of entries like so:

11 Sep 2017 13:37:25,791  INFO DB.HistoryManagerDb - 365696 restore  Restored class org.apache.uima.ducc.transport.event.common.DuccWorkJob
11 Sep 2017 13:37:25,791  INFO DB.HistoryManagerDb - 365692 restore  Restored class org.apache.uima.ducc.transport.event.common.DuccWorkJob
11 Sep 2017 13:37:25,791  INFO DB.HistoryManagerDb - 366293 restore  Restored class org.apache.uima.ducc.transport.event.common.DuccWorkJob
11 Sep 2017 13:37:25,791  INFO DB.HistoryManagerDb - 365794 restore  Restored class org.apache.uima.ducc.transport.event.common.DuccWorkJob

A cache is introduced.  If DB checkpoint dataset access has been attempted within the last minute, we return the last status of: Up or Down.  Otherwise WS attempts to read the checkpoint dataset and resets the status sets the time of last access attempt to the current time.



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