8268893: jcmd to trim the glibc heap

[tstuefe]

Backport the System.trim_native_heap command to 11.

This needs a CSR backport, which exists, it was approved for 11 ages ago (https://bugs.openjdk.org/browse/JDK-8273602) but then the actual backport fell under the table.

The downport is not clean. Since 8282382 had been downported selectively, which introduced print_glibc_malloc_tunables to os_linux.cpp, which sits smack in the middle of the code to change. The hunk affected breaks out the proc-file-reading from the old os::Linux::print_process_memory_info() into os::Linux::query_process_memory_info() - with this patch, both functions are identical now between jdk11u and later releases even though the diff looks different.

Patch was tested in GHAs, and I ran manual tests with jcmd .. System.trim_native_heap, all works.

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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
• Change requires a CSR request to be approved

Issues

• JDK-8268893: jcmd to trim the glibc heap
• JDK-8273602: Add Linux-specific jcmd to trim the C-heap. (CSR)

Reviewers

• Christoph Langer (@RealCLanger - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk11u-dev pull/1354/head:pull/1354
$ git checkout pull/1354

Update a local copy of the PR:
$ git checkout pull/1354
$ git pull https://git.openjdk.org/jdk11u-dev pull/1354/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 1354

View PR using the GUI difftool:
$ git pr show -t 1354

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk11u-dev/pull/1354.diff

[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]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 00: Full (395c8d93)

[tstuefe]

Pinging @RealCLanger (Need JBS Approval to)

[openjdk]

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

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

8268893: jcmd to trim the glibc heap

Reviewed-by: clanger

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 3 new commits pushed to the master branch:

• 0ba5a81: 8276841: Add support for Visual Studio 2022
• 131eab6: 8292541: [Metrics] Reported memory limit may exceed physical machine memory
• f75b74d: 6782021: It is not possible to read local computer certificates with the SunMSCAPI provider

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[tstuefe]

Merci!

/integrate

[openjdk]

Going to push as commit c249ca9.
Since your change was applied there have been 3 commits pushed to the master branch:

• 0ba5a81: 8276841: Add support for Visual Studio 2022
• 131eab6: 8292541: [Metrics] Reported memory limit may exceed physical machine memory
• f75b74d: 6782021: It is not possible to read local computer certificates with the SunMSCAPI provider

Your commit was automatically rebased without conflicts.

[openjdk]

@tstuefe Pushed as commit c249ca9.

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