Joe McDonnell has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/19863 )

Change subject: IMPALA-11941: Support Java 17 in Impala
......................................................................


Patch Set 23:

Do we want a way to fall back to ehcache sizeof? In other words, if we run with 
jamm and we suspect there is an issue, we could restart with the option to use 
the old ehcache implementation. This option is not useful for Java 17 and it 
would still need the add-opens. jamm would be the default.

I'm trying to think about ways to test. Here are random thoughts:
1. Start catalog, load a few tables, compare the size measurements from jamm to 
what we get with ehcache.
2. Start catalog, take a measurement, load a text table (e.g. 
tpcds.store_sales), take a measurement, then load the parquet equivalent 
(tpcds_parquet.store_sales), take another measurement. In theory, the size of 
the metadata for the text table should be close to the same size as the 
metadata for the parquet table?
I don't know if those metrics are easily accessible.

It's not clear what level of testing we need for the accuracy of jamm vs 
ehcache. Then again, we didn't put ehcache through that level of scrutiny.


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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ic378896f572e030a3a019646a96a32a07866a737
Gerrit-Change-Number: 19863
Gerrit-PatchSet: 23
Gerrit-Owner: Michael Smith <[email protected]>
Gerrit-Reviewer: Impala Public Jenkins <[email protected]>
Gerrit-Reviewer: Joe McDonnell <[email protected]>
Gerrit-Reviewer: Laszlo Gaal <[email protected]>
Gerrit-Reviewer: Michael Smith <[email protected]>
Gerrit-Reviewer: Quanlong Huang <[email protected]>
Gerrit-Comment-Date: Tue, 20 Jun 2023 18:04:54 +0000
Gerrit-HasComments: No

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