libjamm-java 0.3.3-1 (amd64 binary) in ubuntu eoan

 Jamm provides MemoryMeter, a java agent to measure actual object memory
 use including JVM overhead.
 .
 MemoryMeter is as accurate as
 java.lang.instrument.Instrumentation.getObjectSize, which only claims
 to provide "approximate" results, but in practice seems to work as
 expected.
 .
 MemoryMeter uses reflection to crawl the object graph for measureDeep.
 By default, MemoryMeter keeps track of descendants visited by
 measureDeep with an IdentityHashMap.