Why does SynchronousExternalCache fail to read entry from cache ( unclassified failure)?

[P]

This problem is possibly related to :  https://jira.atlassian.com/browse/CONFSERVER-57470

On startup of Confluence 6.2 on centos, the following message appears:

[confluence.impl.vcache.SynchronousExternalCache] lambda$get$11 Failed to read entry from cache 'com.atlassian.bandana.BandanaPersister': Failed due to UNCLASSIFIED_FAILURE

.

This message repeats about 50 times, then gives up and Confluence starts up with no problems. However, it wastes a few minutes during startup. 

I turned on log4j debugging for SynchronousExternalCache which revealed the following stacktrace: 

Root cause of failure to read entry from cache 'com.atlassian.bandana.BandanaPersister'
com.atlassian.vcache.ExternalCacheException: Failed due to UNCLASSIFIED_FAILURE

at com.atlassian.vcache.internal.legacy.LecacyUtils.mapException(LegacyUtils.java:51)
at com.atlassian.vcache.internal.legacy.LegacyStableReadExternalCache.mapException(LegacyStableReadExternalCache.java:125)
at com.atlassian.vcache.internal.core.services.AbstractExternalCache.perform(AbstractExternalCache.java:93)
at com.atlassian.vcache.internal.core.services.AbstractExternalCache.perform(AbstractExternalCache.java:69)
at com.atlassian.vcache.internal.core.services.AbstractStableReadExternalCache.get(AbstractStableReadExternalCache.java:100)
at com.atlassian.vcache.internal.core.metrics.TimedExternalCache.get(TimedExternalCache:67)
at com.atlassian.confluence.impl.vcache.SynchronousExternalCache.get(SynchronousExternalCache.java:236)
at com.atlassian.confluence.setup.bandana.ConfluenceCachingBandanaPersister.retrieve(ConfluenceCachingBandanaPersister.java:78)
at com.atlassian.confluence.setup.bandana.ConfluenceCachingBandanaPersister.retrieve(ConfluenceCachingBandanaPersister.java:71)
at com.atlassian.bandana.DefaultBandanaManager.getValue(DefaultBandanaManager.java:32)
at com.atlassian.bandana.DefaultBandanaManager.getValue(DefaultBandanaManager.java:24)

...
...
...
at com.atlassian.sal.confluence.pluginsettings.ConfluencePluginSettings.lambda$get$2(ConfluencePluginSettings.java:68)

...

Would appreciate input from the community. 

[Diego]

Hello there, @P !

Looking further down into our reports, I believe that you are right. It seems that your instance is indeed affected by the situation described here:

• [Confluence Server] [CONFSERVER-57470] Better error reporting in vcache for null lookups

There is still no workaround or solution for this log spam. For the time being, I would advise you to watch and vote for that report. Voting can help to increase the report visibility and watching it will keep you up to date with everything posted there!

Now, would it be possible for you to give us an estimate of how much time those fifty lines of logging take from your startup time?

To do so, send us the timestamp of the first occurrence of the event in your logs and also the last one that occurs before Confluence startup. Please, take care not to share sensitive information here. Our community is an open space where everyone can see everything posted!

Looking forward to your reply. Let us hear from you!

[Logan Hawkes]

I'm not the OP but I have another datapoint. I see the same error repeated every 10 seconds. It doesn't stop after 50 instances. I'm doing an initial install of Confluence 7.3 Datacenter with MySQL 5.7 (remote). It's been repeating for about 20 minutes.