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Differences between Stored session types memdump_simple | memdump_extended | memdump_selective. ?

While I was looking at Server REST Api for creating a memory dump I encountered with the following memory dumps types:

memdump_simple | memdump_extended | memdump_selective.

Can you please explain each type in detail?

1 REPLY 1

1. Simple memory dump is memory snapshot that only tells you the size of each class (without the 'tree' that shows you all the parents-reference-child-realtionship kind of thing underneath) [almost no overhead]

2. Extended memory dump is just like simple memory dump, but instead of snapshot it shows you the whole tree during the time this dump is taken [This one definitely has overhead and will likely impact your application]

3. Selcetive memory dump is the dump that is taken only on certain classed, you have to create a memory-sensor beforehand then only you can take a selective memory dump

AFAIK, normally you take a few simple dump to do comparison first, then identify some suspicious classes growing too fast in memory size, then create a memory sensor to instrument memory allocation of those suspicious classes, then from that points onwards use selective dump to further investigate. Follwoing this typical workflow, you don't need to take a full/extended dump in the first place, which might bring your application suspended.

Andi has a great video on this:

https://youtu.be/SWy83EW_xhk