Using sqlite3 to analyze two jmap heap histograms. Using SQL is a powerful way to query and compare two data sets, like the output of jmap.

gistfile1.txt

jmap -histo:live $pid > old.jmap
sleep $((60*60))
jmap -histo:live $pid > new.jmap
cat old.jmap | awk 'BEGIN { OFS="|" } /:/ { print $2, $3, $4 }' > old.txt
cat new.jmap | awk 'BEGIN { OFS="|" } /:/ { print $2, $3, $4 }' > new.txt
sqlite3
sqlite> create table new(count, bytes, class);
sqlite> create table old(count, bytes, class);
sqlite> .import new.txt "new";
sqlite> .import old.txt "old";
sqlite> select n.class, n.count - o.count, n.bytes - o.bytes as deltabytes from old o, new n where o.class=n.class order by deltabytes desc limit 50;

# Example output:
[I|19932|82352424
[C|24075|23852240
java.lang.String|711673|22773536
[Ljava.lang.Object;|9974|3466336
[Ljava.lang.String;|1415|2754192
[[B|41|2721344
[[I|29151|1402064
net.sf.ehcache.Element|18343|1173952
org.hibernate.cache.spi.CacheKey|36384|1164288
java.lang.Long|46795|1123080
java.util.LinkedHashMap$Entry|22708|908320
org.hibernate.cache.ehcache.internal.strategy.AbstractReadWriteEhcacheAccessStrategy$Lock|12409|694904