AEM 6.2 BlobGarbageCollection - NullPointer Exception

[MircoK_VT]

Hi!

I am using AEM 6.2 with a datastore on external filesystem. Running the BlobStoreGarbageCollection (markOnly=false) via JMX console I get following error:

10.09.2019 08:51:21.882 *ERROR* [sling-oak-observation-334] org.apache.jackrabbi
t.oak.plugins.blob.MarkSweepGarbageCollector Blob garbage collection error
java.lang.NullPointerException: null
        at org.apache.jackrabbit.oak.plugins.blob.datastore.OakFileDataStore$4.a
pply(OakFileDataStore.java:241)
        at org.apache.jackrabbit.oak.plugins.blob.datastore.OakFileDataStore$4.a
pply(OakFileDataStore.java:238)
        at com.google.common.collect.Iterators$7.computeNext(Iterators.java:647)
        at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractI
terator.java:143)
        at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.j
ava:138)
        at com.google.common.collect.TransformedIterator.hasNext(TransformedIter
ator.java:43)
        at com.google.common.collect.Iterators$7.computeNext(Iterators.java:645)
        at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractI
terator.java:143)
        at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.j
ava:138)
        at com.google.common.collect.TransformedIterator.hasNext(TransformedIter
ator.java:43)
        at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector$Blob
IdRetriever.call(MarkSweepGarbageCollector.java:626)
        at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.swee
p(MarkSweepGarbageCollector.java:378)
        at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.mark
AndSweep(MarkSweepGarbageCollector.java:251)
        at org.apache.jackrabbit.oak.plugins.blob.MarkSweepGarbageCollector.coll
ectGarbage(MarkSweepGarbageCollector.java:164)
        at org.apache.jackrabbit.oak.plugins.blob.BlobGC$1.call(BlobGC.java:87)
        at org.apache.jackrabbit.oak.plugins.blob.BlobGC$1.call(BlobGC.java:83)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.
java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:624)
        at java.lang.Thread.run(Thread.java:748)

Mark phase (markOnly=true) seems to be ok:

[...]
10.09.2019 08:51:21.789 *INFO* [sling-oak-observation-334] org.apache.jackrabbit
.oak.plugins.blob.MarkSweepGarbageCollector Collected (40960) blob references
10.09.2019 08:51:21.793 *INFO* [sling-oak-observation-334] org.apache.jackrabbit
.oak.plugins.blob.MarkSweepGarbageCollector Collected (43008) blob references
10.09.2019 08:51:21.795 *INFO* [sling-oak-observation-334] org.apache.jackrabbit
.oak.plugins.blob.MarkSweepGarbageCollector Number of valid blob references mark
ed under mark phase of Blob garbage collection [43530]

Has anyone faced the same issue or can perhaps give me a hint how to solve this issue?

Thank you in advance

Mirco

[Jaideep_Brar · Accepted solution]

This issue has been reported (internal reference is: CQ-103742) and is also visible in the public Oak project, under this reference OAK-5078 [0].

This issue has been fixed in Oak 1.4.10, So, you can upgrade the oak version to 1.4.10 at least from [1] to resolve the issue.

There is however a work-around, which consist to configure the path to the datastore as an absolute path in the file datastore configuration:

path=../datastore  <- TO BE FIXED AS ABSOLUT

minRecordLength=4096

[0] https://issues.apache.org/jira/browse/OAK-5078

[1] Adobe Experience Manager Help | Release Notes: AEM 6.2 Oak Cumulative Fix Pack

[MircoK_VT]

Thank you very much. Workaround solved the issue. I will try to update Oak as soon as possible.