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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