RFR: 8253495: CDS generates non-deterministic output [v2]

[Magnus Ihse Bursie]

On Wed, 9 Mar 2022 05:10:44 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> This patch makes the result of "java -Xshare:dump" deterministic:
>> - Disabled new Java threads from launching. This is harmless. See comments in jvm.cpp
>> - Fixed a problem in hashtable ordering in heapShared.cpp
>> - BasicHashtableEntry has a gap on 64-bit platforms that may contain random bits. Added code to zero it.
>> - Enabled checking of $JAVA_HOME/lib/server/classes.jsa in make/scripts/compare.sh
>> 
>> Note:  $JAVA_HOME/lib/server/classes_ncoops.jsa is still non-deterministic. This will be fixed in [JDK-8282828](https://bugs.openjdk.java.net/browse/JDK-8282828).
>> 
>> Testing under way:
>> - tier1~tier5
>> - Run all *-cmp-baseline jobs 20 times each (linux-aarch64-cmp-baseline, windows-x86-cmp-baseline, .... etc).
>
> Ioi Lam has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixed zero build

Well, previously we'd get different dumps on different runs. If that was an issue, surely it would have manifested itself by now? With this change, we'll just get the same dump each run. I fail to see how that could be a risk.

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PR: https://git.openjdk.java.net/jdk/pull/7748