8303267: Prefer ArrayList to LinkedList in ConcurrentLocksPrinter

[turbanoff]

LinkedList is used as value in sun.jvm.hotspot.runtime.ConcurrentLocksPrinter#locksMap Map.
There is only add/iterator calls on this lists. No removes from the head or something like this. Not sure why LinkedList was used, but ArrayList should be preferred as more efficient and widely used collection.

Also I've done some related code cleaned:

1. Mark field locksMap as final
2. Use Map.computeIfAbsent
3. Use enhanced-for cycle instead of for with iterator

---

Progress

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Issue

• JDK-8303267: Prefer ArrayList to LinkedList in ConcurrentLocksPrinter

Reviewers

• Chris Plummer (@plummercj - Reviewer)
• Serguei Spitsyn (@sspitsyn - Reviewer)

Reviewing

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Webrevs

• 00: Full (39ac116d)

[openjdk]

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

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

8303267: Prefer ArrayList to LinkedList in ConcurrentLocksPrinter

Reviewed-by: cjplummer, sspitsyn

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At the time when this comment was updated there had been 14 new commits pushed to the master branch:

• 5feb13b: 8301701: java/net/DatagramSocket/DatagramSocketMulticasting.java should be hardened
• 1e3c9fd: 8026369: javac potentially ambiguous overload warning needs an improved scheme
• 14a014d: 8302124: HotSpot Style Guide should permit noreturn attribute
• bca60f4: 8303249: JFR: Incorrect description of dumponexit
• f7f1036: 8303068: Memory leak in DwarfFile::LineNumberProgram::run_line_number_program
• 784f7b1: 8293667: Align jlink's --compress option with jmod's --compress option
• 54603aa: 8303208: JFR: 'jfr print' displays incorrect timestamps
• 4c169d2: 8303253: Remove unnecessary calls to super() in java.time value based classes
• b527edd: 8292914: Lambda proxies have unstable names
• 42330d2: 8029370: (fc) FileChannel javadoc not clear for cases where position == size
• ... and 4 more: https://git.openjdk.org/jdk/compare/f2b03f9a2c0fca853211e41a1ddf46195dd56698...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.

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[sspitsyn]

Looks good.
Thanks,
Serguei

[turbanoff]

/integrate

[openjdk]

Going to push as commit d4dcba0.
Since your change was applied there have been 53 commits pushed to the master branch:

• 2c7d2c0: 8303411: JFR problem list entry for JDK-8247776 should be removed
• 0b63557: 8303039: Utilize coverageLevels.txt
• 32247c3: 8303476: Add the runtime version in the release file of a JDK image
• 0926d0c: 8302516: Do some cleanup of nsk/share/jdi/EventHandler.java
• b51ea42: 8303354: addCertificatesToKeystore in KeystoreImpl.m needs CFRelease call in early potential CHECK_NULL return
• fb13063: 8303409: Add Windows AArch64 ABI support to the Foreign Function & Memory API
• c9afd55: 8302820: Remove costs for NMTPreInit when NMT is off
• 72de24e: 8303457: Introduce convenience test library APIs for creating test servers for tests in test/jdk/java/net/httpclient
• 3091744: 8303418: Improve parameter and variable names in BitMap
• dbb562d: 8303355: The Depend plugin does fully recompile when primitive type changes
• ... and 43 more: https://git.openjdk.org/jdk/compare/f2b03f9a2c0fca853211e41a1ddf46195dd56698...master

Your commit was automatically rebased without conflicts.

[openjdk]

@turbanoff Pushed as commit d4dcba0.

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