8332514: Allow class space size to be larger than 3GB

[tstuefe]

Class space size is capped at 3GB. Technically, the Klass encoding range is 4GB.

We cap class space at 3GB to leave breathing room for CDS. However, CDS needs a lot less, so we waste address space. In addition, class space is unnecessarily capped at 3GB even if we run without CDS, which is unnecessary.

What we should do instead:

• if CDS is off, use the full 4GB
• if CDS is on, use as much memory as we can after accommodating the archive

This patch implements that new behavior.

Now, we can have 4GB class space without CDS; with CDS, a bit less (depends on the CDS archive size; by default, on MacOS, we reach about 3.98GB).

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8332514: Allow class space size to be larger than 3GB (Enhancement - P4)

Reviewers

• Ioi Lam (@iklam - Reviewer)
• David Holmes (@dholmes-ora - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/19347/head:pull/19347
$ git checkout pull/19347

Update a local copy of the PR:
$ git checkout pull/19347
$ git pull https://git.openjdk.org/jdk.git pull/19347/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 19347

View PR using the GUI difftool:
$ git pr show -t 19347

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/19347.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back stuefe! 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]

@tstuefe 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:

8332514: Allow class space size to be larger than 3GB

Reviewed-by: iklam, dholmes

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 118 new commits pushed to the master branch:

• 91101f0: 8333353: Delete extra empty line in CodeBlob.java
• e0ac824: 8332959: C2: ZGC fails with 'Incorrect load shift' when invoking Object.clone() reflectively on an array
• d2d78ad: 8280990: [XWayland] XTest emulated mouse click does not bring window to front
• 7c83d7a: 8333366: C2: CmpU3Nodes are not pushed back to worklist in PhaseCCP leading to non-fixpoint assertion failure
• 75220da: 8333154: RISC-V: Add support for primitive array C1 clone intrinsic
• a4c7be8: 8333006: RISC-V: C2: Support vector-scalar and vector-immediate arithmetic instructions
• cfe91ed: 8333276: RISC-V: client VM build failure after JDK-8241503
• 769b3e4: 8333182: Add truncated tracing mode for TraceBytecodes
• 8338946: 8332935: Crash: assert(*lastPtr != 0) failed: Mismatched JNINativeInterface tables, check for new entries
• 4785461: 7022325: TEST_BUG: test/java/util/zip/ZipFile/ReadLongZipFileName.java leaks files if it fails
• ... and 108 more: https://git.openjdk.org/jdk/compare/97ee2ffb89257a37a178b70c8fee96a1d831deb6...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[openjdk]

@tstuefe The following label will be automatically applied to this pull request:

• hotspot-runtime

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[tstuefe]

Pinging @iklam. And @coleenp, maybe?

[mlbridge]

Webrevs

• 01: Full - Incremental (2d33ad47)
• 00: Full (ba013f2f)

[tstuefe]

@iklam Thanks for the review.

• I replaced the offending assert with one requiring archive size to be smaller than 4G - 16MB, for a theoretical minimal class space size of 16MB.
• I rewrote the test. I split it into several independently executed parts, and only the part doing the dumping requires CDS. I also explicitly dump now, with an explicitly given archive.

[iklam]

LGTM. Thanks for making the changes.

[tstuefe]

Thanks @iklam !

@rkennke could you take a look please? Its simple.

[tstuefe]

Anyone else? I would like to get this into 23, and the patch is not complex. Thanks!

[dholmes-ora]

Seems reasonable. Thanks.

[tstuefe]

Many thanks, @dholmes-ora and @iklam !

/integrate

[openjdk]

Going to push as commit b101586.
Since your change was applied there have been 119 commits pushed to the master branch:

• 5ed0d52: 8332936: Test vmTestbase/metaspace/gc/watermark_70_80/TestDescription.java fails with no GC's recorded
• 91101f0: 8333353: Delete extra empty line in CodeBlob.java
• e0ac824: 8332959: C2: ZGC fails with 'Incorrect load shift' when invoking Object.clone() reflectively on an array
• d2d78ad: 8280990: [XWayland] XTest emulated mouse click does not bring window to front
• 7c83d7a: 8333366: C2: CmpU3Nodes are not pushed back to worklist in PhaseCCP leading to non-fixpoint assertion failure
• 75220da: 8333154: RISC-V: Add support for primitive array C1 clone intrinsic
• a4c7be8: 8333006: RISC-V: C2: Support vector-scalar and vector-immediate arithmetic instructions
• cfe91ed: 8333276: RISC-V: client VM build failure after JDK-8241503
• 769b3e4: 8333182: Add truncated tracing mode for TraceBytecodes
• 8338946: 8332935: Crash: assert(*lastPtr != 0) failed: Mismatched JNINativeInterface tables, check for new entries
• ... and 109 more: https://git.openjdk.org/jdk/compare/97ee2ffb89257a37a178b70c8fee96a1d831deb6...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tstuefe Pushed as commit b101586.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.