8282828: CDS uncompressed oops archive is not deterministic

[iklam]

During java -Xshare:dump -XX:-UseCompressedOops, the location of the Java heap is chosen by the OS. Due to Address Space Layout Randomization, the heap will always start at a different location. This causes the archive for uncompressed oops ($JAVA_HOME/lib/server/classes_nocoops.jsa) to be non-deterministic.

The fix is to patch the archived object pointers to make it look like the heap starts at a fixed address -- I chose 0x10000000, but the exact value doesn't really matter.

At runtime, the object pointers will be patched again according to the real location of the heap.

Tested with tiers 1-5. I am running builds-tier5 several times to test the xxx-cmp-baseline builds.

---

Progress

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Issue

• JDK-8282828: CDS uncompressed oops archive is not deterministic

Reviewers

• Erik Joelsson (@erikj79 - Reviewer) ⚠️ Review applies to f0261c51
• Magnus Ihse Bursie (@magicus - Reviewer) ⚠️ Review applies to f0261c51
• Calvin Cheung (@calvinccheung - Reviewer) ⚠️ Review applies to f0261c51

Reviewing

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[bridgekeeper]

👋 Welcome back iklam! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@iklam The following labels will be automatically applied to this pull request:

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[iklam]

This fix doesn't affect the contents of the archive, but it's necessary to avoid incorrect output from -Xlog:cds+map=trace.

[mlbridge]

Webrevs

• 01: Full - Incremental (8ddea12f)
• 00: Full (f0261c51)

[erikj79]

Change to compare.sh looks good. Thanks for fixing this!

[erikj79]

/reviewers 2

[openjdk]

@iklam This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8282828: CDS uncompressed oops archive is not deterministic

Reviewed-by: erikj, ihse, ccheung

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[openjdk]

@erikj79
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with 1 of role reviewers, 1 of role authors).

[magicus]

Looks good to me. But you need hotspot reviewers as well.

And thanks for fixing this! I think this is the last major known non-reproducibility bug in the JDK! 🎉

/reviewers 3

[openjdk]

@magicus
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 3 (with 1 of role reviewers, 2 of role authors).

[calvinccheung]

LGTM

[iklam]

Thanks @erikj79 @magicus @calvinccheung for the review.
/integrate

[openjdk]

Going to push as commit 64b5b2b.
Since your change was applied there has been 1 commit pushed to the master branch:

• 45ca81f: 8285915: failure_handler: gather the contents of /etc/hosts file

Your commit was automatically rebased without conflicts.

[openjdk]

@iklam Pushed as commit 64b5b2b.

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