JDK-8284165: Add pid to process reaper thread name

[tstuefe]

To help with analyzing fork-heavy scenarios, it would help if we could see at one glance which process a reaper is servicing. A pragmatic way would be to add the pid to its name - that way, e.g. thread dumps with lots of reaper threads would be more enlightening.

Since reaper threads get reused we have to change the name back to some base name when the reaper is done with the process. This has the additional benefit of showing us in the thread dump which reapers are actually reaping, and which are just idling around in the pool.

With this patch, reaper threads are:

• named "reaper thread (pid: xxx)" when assigned to a process
• remain named "reaper thread" without pid when not being assigned to a process.

thomas@starfish:/shared/projects/openjdk/jdk-jdk/source$ jcmd Test Thread.print | grep 'reaper'
"process reaper (pid 1358320)" #114 daemon prio=10 os_prio=0 cpu=4034,46ms elapsed=20,66s tid=0x00007f7860003ec0 nid=1277510 runnable  [0x00007f7944765000]
"process reaper" #105 daemon prio=10 os_prio=0 cpu=0,51ms elapsed=20,66s tid=0x00007f7900099e20 nid=1277511 waiting on condition  [0x00007f7944031000]
"process reaper" #102 daemon prio=10 os_prio=0 cpu=0,24ms elapsed=20,66s tid=0x00007f78b0003720 nid=1277512 waiting on condition  [0x00007f7869cca000]
"process reaper" #110 daemon prio=10 os_prio=0 cpu=0,39ms elapsed=20,66s tid=0x00007f78a8003260 nid=1277517 waiting on condition  [0x00007f7869c16000]
"process reaper" #106 daemon prio=10 os_prio=0 cpu=0,34ms elapsed=20,66s tid=0x00007f78480034a0 nid=1277518 waiting on condition  [0x00007f7869bf2000]
"process reaper (pid 1358355)" #118 daemon prio=10 os_prio=0 cpu=2762,03ms elapsed=20,66s tid=0x00007f78800042a0 nid=1277519 runnable  [0x00007f7869b8e000]
"process reaper" #119 daemon prio=10 os_prio=0 cpu=0,20ms elapsed=20,66s tid=0x00007f78a0013610 nid=1277520 waiting on condition  [0x00007f7869b6a000]
"process reaper (pid 1358365)" #97 daemon prio=10 os_prio=0 cpu=3608,37ms elapsed=20,66s tid=0x00007f78f4005b70 nid=1277521 runnable  [0x00007f7869bce000]
"process reaper (pid 1358388)" #95 daemon prio=10 os_prio=0 cpu=6079,07ms elapsed=20,66s tid=0x00007f7898003260 nid=1277522 runnable  [0x00007f7869b46000]
"process reaper" #86 daemon prio=10 os_prio=0 cpu=3897,96ms elapsed=20,66s tid=0x00007f7890003ce0 nid=1277523 waiting on condition  [0x00007f7869b22000]
"process reaper (pid 1358389)" #115 daemon prio=10 os_prio=0 cpu=5020,85ms elapsed=20,66s tid=0x00007f783c003840 nid=1277524 runnable  [0x00007f7869afe000]
"process reaper" #111 daemon prio=10 os_prio=0 cpu=4823,39ms elapsed=20,66s tid=0x00007f78fc111c20 nid=1277525 waiting on condition  [0x00007f7869ada000]
"process reaper" #91 daemon prio=10 os_prio=0 cpu=2566,21ms elapsed=20,66s tid=0x00007f78840042c0 nid=1277526 waiting on condition  [0x00007f7869ab6000]
"process reaper" #81 daemon prio=10 os_prio=0 cpu=2954,63ms elapsed=20,66s tid=0x00007f78c8003e90 nid=1277527 waiting on condition  [0x00007f7869a92000]
"process reaper" #121 daemon prio=10 os_prio=0 cpu=2966,19ms elapsed=20,66s tid=0x00007f789c003910 nid=1277528 waiting on condition  [0x00007f7869a6e000]

Tests:

• I manually tested java/lang/Process* jtreg test groups, as well as java/util/concurrent/Phaser
• GHAs
• nightlies at SAP scheduled

---

Progress

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Issue

• JDK-8284165: Add pid to process reaper thread name

Reviewers

• Roger Riggs (@RogerRiggs - Reviewer)

Reviewing

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[tstuefe]

GHA: windows x64 error unrelated

[mlbridge]

Webrevs

• 01: Full - Incremental (b76b5e87)
• 00: Full (4c0e634c)

[RogerRiggs]

LGTM
A refactoring of the run method would be ok, but not essential.

[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:

8284165: Add pid to process reaper thread name

Reviewed-by: rriggs

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 18 new commits pushed to the master branch:

• 4e20a03: 8283044: Use asynchronous handshakes to deliver asynchronous exceptions
• 9d200d6: 8282756: Make ElementKind checks more specific
• 1012d59: 8281079: [s390] Unify Address Operand Encoding in Instruction Emitters
• 003ec21: 8279508: Auto-vectorize Math.round API
• c1e67b6: 8283474: Include detailed heap object info in CDS map file
• 060a188: 8283865: riscv: Break down -XX:+UseRVB into seperate options for each bitmanip extension
• e5e1aab: 8284068: riscv: should call Atomic::release_store in JavaThread::set_thread_state
• 0b09f70: 8273553: sun.security.ssl.SSLEngineImpl.closeInbound also has similar error of JDK-8253368
• afd0f5a: 8284190: disable G1RegionToSpaceMapper.largeStressAdjacent_vm on windows
• 028fbf4: 8254935: Deprecate the PSSParameterSpec(int) constructor
• ... and 8 more: https://git.openjdk.java.net/jdk/compare/bab431cc120fe09be371dadef0c1caf79ec9eef4...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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[tstuefe]

Thanks @AlanBateman and @RogerRiggs !

/integrate

[openjdk]

Going to push as commit 9561b5e.
Since your change was applied there have been 29 commits pushed to the master branch:

• 36b3bbc: 8284033: Leak XVisualInfo in getAllConfigs in awt_GraphicsEnv.c
• 59fe31a: 8284170: Add "make doctor" to the make help
• 9440b39: 8283215: [macos] Screen Magnifier: Getting java.awt.IllegalComponentStateException when menu item is selected
• 86caf60: 8283703: Add sealed modifier to java.awt.geom.Path2D
• 0cd46f6: 8283597: [REDO] Invalid generic signature for redefined classes
• e297074: 8284181: ArgumentsTest.set_numeric_flag_double_vm fails on some locales
• 732f7ae: 8284071: Collapse identical catch branches in jdk.console
• 61d06c2: 8276050: XMLInputFactoryImpl.getProperty() returns null
• 7381868: 8283623: Create an automated regression test for JDK-4525475
• f76f5da: 5087440: java.io bulk read(...) end-of-stream return value descriptions ambiguous
• ... and 19 more: https://git.openjdk.java.net/jdk/compare/bab431cc120fe09be371dadef0c1caf79ec9eef4...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tstuefe Pushed as commit 9561b5e.

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