Integrated: 8298126: Print statistics for objects in CDS archive heap

[Ioi Lam]

On Mon, 5 Dec 2022 22:09:58 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> For diagnostic purposes, it's useful to print out statistics of the objects in the CDS archive heap. For example, this shows the number of objects with a distribution of different sizes.
> 
> 
> [6.772s][info][cds,heap]        0 objects are <= 8      bytes (total        0 bytes, avg      0.0 bytes)
> [6.772s][info][cds,heap]     1205 objects are <= 16     bytes (total    19280 bytes, avg     16.0 bytes)
> [6.772s][info][cds,heap]    15717 objects are <= 32     bytes (total   411024 bytes, avg     26.2 bytes)
> [6.772s][info][cds,heap]     4127 objects are <= 64     bytes (total   198080 bytes, avg     48.0 bytes)
> [6.772s][info][cds,heap]     2380 objects are <= 128    bytes (total   243016 bytes, avg    102.1 bytes)
> [6.772s][info][cds,heap]      293 objects are <= 256    bytes (total    47920 bytes, avg    163.5 bytes)
> [6.772s][info][cds,heap]       51 objects are <= 512    bytes (total    17112 bytes, avg    335.5 bytes)
> [6.772s][info][cds,heap]       18 objects are <= 1024   bytes (total    14480 bytes, avg    804.4 bytes)
> [6.772s][info][cds,heap]       11 objects are <= 2048   bytes (total    13440 bytes, avg   1221.8 bytes)
> [6.772s][info][cds,heap]        3 objects are <= 4096   bytes (total     9808 bytes, avg   3269.3 bytes)
> [6.772s][info][cds,heap]        3 objects are <= 8192   bytes (total    12840 bytes, avg   4280.0 bytes)
> [6.772s][info][cds,heap]        4 objects are <= 16384  bytes (total    37240 bytes, avg   9310.0 bytes)
> [6.772s][info][cds,heap]        0 objects are <= 32768  bytes (total        0 bytes, avg      0.0 bytes)
> [6.772s][info][cds,heap]        0 objects are <= 65536  bytes (total        0 bytes, avg      0.0 bytes)
> [6.772s][info][cds,heap]        0 objects are <= 131072 bytes (total        0 bytes, avg      0.0 bytes)
> [6.772s][info][cds,heap]        0 objects are <= 262144 bytes (total        0 bytes, avg      0.0 bytes)
> [6.772s][info][cds,heap]        0 huge  objects               (total        0 bytes, avg      0.0 bytes)
> [6.772s][info][cds,heap]    23812 total objects               (total  1024240 bytes, avg     43.0 bytes)
> 
> 
> These stats are useful when implement large changes in the CDS heap archiving code. For example, [JDK-8296344](https://bugs.openjdk.org/browse/JDK-8296344) significantly changes how the objects are copied into the archive. We can use these stats to verify that the exact same objects are copied.

This pull request has now been integrated.

Changeset: a37de62d
Author:    Ioi Lam <iklam at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/a37de62d9ddadf1490ee59bd03224e8cea70a75b
Stats:     64 lines in 2 files changed: 64 ins; 0 del; 0 mod

8298126: Print statistics for objects in CDS archive heap

Reviewed-by: ccheung

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PR: https://git.openjdk.org/jdk/pull/11520