Heap Dump Analysis - Find root cause of OutOfMemory Exception

Question

I am running an application that has 4 gigs of maxmimum heap size -Xms4096m -Xmx4096m -Xmn1024m with GC configured as -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=50 and GC interval of Dsun.rmi.dgc.server.gcInterval=43200000 -Dsun.rmi.dgc.client.gcInterval=43200000

Suddenly my application went to heap out of memory exception and i took thread dumps and heap dumps on the same occasion. On analyzing Thread dumps, thread are stuck due to creating some value to a hashMap and arrayList. ByteArrayOutStream has created locks in one of the thread.

On Analysing Heap dump in eclipse memory analyzer tool, it clearly says bytearray object has occupied almost 1 Gigs of Heap. From the GCViewer it shows it has a peak in fraction of second. I am clue less why suddenly Byte array object used 1 Gigs of space. Can some one help me out to narrow down the culprit.

-- Application Server - Weblogic 12c

Answer 1

On Analysing Heap dump in eclipse memory analyzer tool, it clearly says bytearray object has occupied almost 1 Gigs of Heap.

Use the shortest paths to GC root feature of MAT to see which references are holding onto that byte array.