8354872: Clarify java.lang.Process resource cleanup #25884

RogerRiggs · 2025-06-18T20:16:18Z

Improve the documentation of Process use of system resources.

Describe the implementation closing streams when no longer referenced.
Clarify the interactions between inputStream and inputReader and errorStream and errorReader.
Add advice and example using try-with-resources to open and close streams.
Recommend closing streams when no longer in use.

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 CSR request JDK-8356311 to be approved

Issues

JDK-8354872: Clarify java.lang.Process resource cleanup (Bug - P4)
JDK-8356311: Clarify java.lang.Process resource cleanup (CSR)

Reviewers

Jaikiran Pai (@jaikiran - Reviewer)

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Recommend closing streams when no longer in use. Describe the implementation closing streams when no longer referenced. Clarify the interactions between inputStream and inputReader and errorStream and errorReader. Add advice and example using try-with-resources to open and close streams.

bridgekeeper · 2025-06-18T20:26:14Z

👋 Welcome back rriggs! 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 · 2025-06-18T20:26:35Z

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

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8354872: Clarify java.lang.Process resource cleanup

Reviewed-by: jpai

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At the time when this comment was updated there had been 199 new commits pushed to the master branch:

77e69e0: 8358750: JFR: EventInstrumentation MASK_THROTTLE* constants should be computed in longs
dcc7254: 8361213: J2DAnalyzer should emit the score as a decimal
003be0d: 8361325: Refactor ClassLoaderExt
... and 196 more: https://git.openjdk.org/jdk/compare/e55ddabffa90e28d22f546b387007fe4e434c3e0...master

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openjdk · 2025-06-18T20:27:15Z

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

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mlbridge · 2025-06-18T20:29:53Z

Webrevs

vy

The addendum on resource management looks very useful, thanks! 💯

Shall we also

Create a dedicated section on resource management
Document the effect of destroy() and destroyForcibly() (and onExit()?) on releasing resources

…to the ProcessBuilder constructor. Plus copyright update

src/java.base/share/classes/java/lang/Process.java

src/java.base/share/classes/java/lang/ProcessBuilder.java

jaikiran · 2025-06-27T16:26:12Z

The copyright years on these files will need an update.

And copyrights.

RogerRiggs · 2025-07-01T22:27:44Z

Please also review the CSR.
JDK-8356311: Clarify java.lang.Process resource use

src/java.base/share/classes/java/lang/Process.java

jaikiran · 2025-07-02T13:02:04Z

src/java.base/share/classes/java/lang/Process.java

     * @apiNote
-     * Use {@link #getInputStream()} and {@link #inputReader()} with extreme care.
-     * The {@code BufferedReader} may have buffered input from the input stream.
+     * Use either this method or an {@linkplain #inputReader(Charset) input reader}


I think this should be {@linkplain #inputReader() input reader} (i.e. the one that doesn't take a CharSet) to match what was there previously before the changes in this PR.

Conundrum... The readable text refers to "an input reader" and covers the case of either inputReader method.
But including both links makes the sentence hard to read, so I picked the more expressive reader method to link to.
Reverting to no-arg version.

Ditto below.

But including both links makes the sentence hard to read, so I picked the more expressive reader method to link to.

It didn't realize you had intentionally used the CharSet one. If you think the CharSet would provide better guidance to the developers, then I think it's OK to switch to that one.

src/java.base/share/classes/java/lang/Process.java

jaikiran · 2025-07-02T13:06:32Z

The updated changes look good to me. I just noticed a few typoes which I've reviewed inline. I'll review the CSR now.

src/java.base/share/classes/java/lang/ProcessBuilder.java

…direct.DISCARD.

jaikiran

Thank you Roger for these updates. This looks good to me.

src/java.base/share/classes/java/lang/Process.java

RogerRiggs · 2025-07-07T12:42:01Z

/integrate

openjdk · 2025-07-07T12:43:34Z

Going to push as commit afb4a1b.
Since your change was applied there have been 221 commits pushed to the master branch:

7c13a2c: 8361463: Render method of javax.swing.text.AbstractDocument uses 'currency' instead of 'concurrency'
4df9c87: 8360884: Better scoped values
9449fea: 8358552: EndOfFileException in System.in.read() and IO.readln() etc. in JShell
... and 218 more: https://git.openjdk.org/jdk/compare/e55ddabffa90e28d22f546b387007fe4e434c3e0...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-07-07T12:43:46Z

@RogerRiggs Pushed as commit afb4a1b.

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

RogerRiggs · 2025-07-07T18:12:53Z

/backport :jdk25

openjdk · 2025-07-07T18:13:26Z

@RogerRiggs the backport was successfully created on the branch backport-RogerRiggs-afb4a1be-jdk25 in my personal fork of openjdk/jdk. To create a pull request with this backport targeting openjdk/jdk:jdk25, just click the following link:

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Hi all,

This pull request contains a backport of commit afb4a1be from the openjdk/jdk repository.

The commit being backported was authored by Roger Riggs on 7 Jul 2025 and was reviewed by Jaikiran Pai.

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openjdk bot added csr Pull request needs approved CSR before integration rfr Pull request is ready for review labels Jun 18, 2025

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vy reviewed Jun 23, 2025

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Update example to use Reader.allAllLines() and simplify passing args …

8ce0b95

…to the ProcessBuilder constructor. Plus copyright update

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RogerRiggs added 2 commits June 27, 2025 15:01

Revised Process and ProcessBuilder doc with reviewer suggestions.

8be5b02

And copyrights.

javadoc cleanup

868c93a

jaikiran reviewed Jul 2, 2025

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Fix links per review comments and snippet syntax in ProcessBuilder.Re…

eafd561

…direct.DISCARD.

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8354872: Clarify java.lang.Process resource cleanup #25884

8354872: Clarify java.lang.Process resource cleanup #25884

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