Analyze

These modes answer what is in memory and what is big. They work on a single dump. To find out what keeps something alive, go to Trace holders. To see what changed over time, go to Compare.

Start here

1. Summary is the default mode. Run it first on any dump to see the shape of the heap.
2. Leak suspects ranks the objects that keep the most alive, so you need no prior idea where to look.
3. Content previews turn "a 5 MiB char[]" into "a JSON document".

Your goal, and the page

Your goal	Command	Page
See what takes the space, by class	heaptrail -i heap.hprof	Summary
Rank classes by what they keep alive	--retained-size	Retained size
Find what is wrong without knowing where to look	--leak-suspects --exclude-soft-weak	Leak suspects
See the content of large arrays	--preview-bytes 200	Content previews
List every string, or every large text array	-l	List strings and arrays
Find the biggest bitmaps	--bitmaps	Bitmaps
Find the code that allocated something	--allocation-sites	Allocation sites

Recipes

Your problem	Recipe
One giant array and no idea what it is	Identify a giant array
The same large payload may be in memory many times	Find duplicate payloads
A dump you did not take, from an app you do not know	Triage an unfamiliar dump

Related

• Concepts explains shallow and retained size.
• Trace holders is the next step once you have a class or an id.
• Choose the right mode maps questions to commands.