8275185: Remove dead code and clean up jvmstat LocalVmManager #5923

iklam · 2021-10-13T04:17:25Z

LocalVmManager and PerfDataFile have APIs that are supposed to look for VMs owned by a specific user. No one uses these APIs, and they don't work anyway.

The current code is very confusing to look at. Since we're likely to change code in this area for further container support, it's better to clean up the code now.

Remove all APIs that take a user name
Also removed PerfDataFile.getFile() methods that are unused
Cleaned up the code that looks up the hsperfdata_xxx files
- Fix comments to explain what's happening
- Avoid using Matcher.reset which is not thread-safe
- Renamed confusing variables such as userFilter to make the code more readable
- LocalVmManager.activeVms() probably doesn't need to be synchronized, but I kept it anyway to avoid unnecessary risks.

Testing with Oracle CI: tiers1-4, plus hs-tier5-rt (which tests containers and have extensive use of the management tools).

Progress

Change must not contain extraneous whitespace
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Change must be properly reviewed

Issue

JDK-8275185: Remove dead code and clean up jvmstat LocalVmManager

Reviewers

Chris Plummer (@plummercj - Reviewer)
Claes Redestad (@cl4es - Reviewer)
Kevin Walls (@kevinjwalls - Committer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/5923/head:pull/5923
$ git checkout pull/5923

Update a local copy of the PR:
$ git checkout pull/5923
$ git pull https://git.openjdk.java.net/jdk pull/5923/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 5923

View PR using the GUI difftool:
$ git pr show -t 5923

Using diff file

Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/5923.diff

bridgekeeper · 2021-10-13T04:18:48Z

👋 Welcome back iklam! 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 · 2021-10-13T04:20:19Z

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

serviceability

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.

mlbridge · 2021-10-13T04:28:15Z

Webrevs

01: Full - Incremental (bbeb7c16)
00: Full (c2f3937b)

plummercj · 2021-10-19T21:17:57Z

...internal.jvmstat/share/classes/sun/jvmstat/perfdata/monitor/protocol/local/PerfDataFile.java

-    /**
-     * The directory name pattern for the user directories.
-     */
-    public static final String userDirNamePattern = "hsperfdata_\\S*";
-
-    /**
-     * The file name pattern for PerfData shared memory files.
-     * <p>
-     * This pattern must be kept in synch with the file name pattern
-     * used by the 1.4.2 and later HotSpot JVM.
-     */
-    public static final String fileNamePattern = "^[0-9]+$";
-
-    /**
-     * The file name pattern for 1.4.1 PerfData shared memory files.
-     * <p>
-     * This pattern must be kept in synch with the file name pattern
-     * used by the 1.4.1 HotSpot JVM.
-     */
-    public static final String tmpFileNamePattern =
-            "^hsperfdata_[0-9]+(_[1-2]+)?$";
-
-


I don't understand why you thought it best to remove these and instead use hard coded references to these partterns.

I have two goals

these aren't used anywhere else, so it's better to at least move them from this file to LocalVmManager.java, where they are actually used. So you don't need to flip between two files.

the behavior is easier to understand if the string literals, comments, and the code that uses them are together.

Note that the original code has plenty of comment that are rather useless if you want to know how the files are searched.

plummercj · 2021-10-19T21:57:31Z

...internal.jvmstat/share/classes/sun/jvmstat/perfdata/monitor/protocol/local/PerfDataFile.java

-    /**
-     * The directory name pattern for the user directories.
-     */
-    public static final String userDirNamePattern = "hsperfdata_\\S*";
-
-    /**
-     * The file name pattern for PerfData shared memory files.
-     * <p>
-     * This pattern must be kept in synch with the file name pattern
-     * used by the 1.4.2 and later HotSpot JVM.
-     */
-    public static final String fileNamePattern = "^[0-9]+$";
-
-    /**
-     * The file name pattern for 1.4.1 PerfData shared memory files.
-     * <p>
-     * This pattern must be kept in synch with the file name pattern
-     * used by the 1.4.1 HotSpot JVM.
-     */
-    public static final String tmpFileNamePattern =
-            "^hsperfdata_[0-9]+(_[1-2]+)?$";
-
-


plummercj · 2021-10-19T21:59:18Z

...ternal.jvmstat/share/classes/sun/jvmstat/perfdata/monitor/protocol/local/LocalVmManager.java

-                            }
-                        }
-                    }
+            // 1.4.2 and later: Look for the files {tmpdir}/hsperfdata_{any_user_name}/[0-0]+


should be [0-9]+

plummercj · 2021-10-19T22:02:58Z

...ternal.jvmstat/share/classes/sun/jvmstat/perfdata/monitor/protocol/local/LocalVmManager.java

-        tmpFileFilter = new FilenameFilter() {
+        // 1.4.1 (or earlier?): the files are stored directly under {tmpdir}/ with
+        // the following pattern.
+        Pattern oldtmpFilePattern = Pattern.compile("^hsperfdata_[0-9]+(_[1-2]+)?$");


So this pattern optionally has _ followed by a sequence of 1's and 2's at the end? Seems odd.

I restored this line to use PerfDataFile.tmpFileNamePattern, as before my changes. Yes, that's an odd way of naming a file.

sspitsyn · 2021-10-20T02:23:25Z

Hi Ioi,
It looks good to me except the line 105 commented by Chris.
I wonder how should this be tested to make sure there are no regressions.
Do we really care about pre 1.4.2 formats? If so, what is the way to test it?
We have a little lack of knowledge in this area.
I guess, we need the performance team to get involved into this review.
Thanks,
Serguei

kevinjwalls · 2021-10-26T07:48:05Z

Nice cleanup - although was it not better for PerfDataFile.java to "own" the definitions of what a perfdata filename looks like?
That might be what Chris was hinting at. There isn't really that much flipping between two files. 8-)

…NamePattern, etc. (2) Fixed comments

iklam · 2021-11-04T02:06:01Z

Hi Ioi, It looks good to me except the line 105 commented by Chris. I wonder how should this be tested to make sure there are no regressions. Do we really care about pre 1.4.2 formats? If so, what is the way to test it? We have a little lack of knowledge in this area. I guess, we need the performance team to get involved into this review. Thanks, Serguei

I am not sure about 1.4.2 formats. I guess we don't really care, but we should probably remove it in a separate RFE. I am trying to keep this PR from having any functional changes, and will just remove dead code.

For testing, I am running tiers 1-4. Will that be enough?

I'll ping the performance team.

Thanks

Ioi

iklam · 2021-11-04T02:07:42Z

Nice cleanup - although was it not better for PerfDataFile.java to "own" the definitions of what a perfdata filename looks like? That might be what Chris was hinting at. There isn't really that much flipping between two files. 8-)

Hi Kevin, thanks for the review. I've moved the filename patterns back to PerfDataFile.java as you suggested.

…-remove-dead-code

openjdk · 2021-11-04T03:45:54Z

@iklam 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:

8275185: Remove dead code and clean up jvmstat LocalVmManager

Reviewed-by: cjplummer, redestad, kevinw

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 30 new commits pushed to the master branch:

3613ce7: 8275586: Zero: Simplify interpreter initialization
c62b347: 8276623: JDK-8275650 accidentally pushed "out" file
a1f4c42: 8276227: ciReplay: SIGSEGV if classfile for replay compilation is not present after JDK-8275868
9eadcbb: 8276217: Harmonize StrictMath intrinsics handling
fb0be81: 8276096: Simplify Unsafe.{load|store}Fence fallbacks by delegating to fullFence
558ee40: 8276615: Update CR number of some tests in ProblemList-zgc.txt
603bba2: 8271420: Extend CDS custom loader support to Windows platform
ce8c767: 8276220: Reduce excessive allocations in DateTimeFormatter
0ab910d: 8276066: Reset LoopPercentProfileLimit for x86 due to suboptimal performance
f3320d2: 8276588: Change "ccc" to "CSR" in HotSpot sources
... and 20 more: https://git.openjdk.java.net/jdk/compare/495c828ae95205885b091dde795b517ba332a2b1...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.

cl4es

Supporting 1.4.1 hsperfdata seems pointless at this point, so I support a removal of that code. It also seems reasonable to do as a follow-up, as @iklam suggests, rather than shifting the scope this PR.

kevinjwalls · 2021-11-04T11:20:32Z

...moved the filename patterns back to PerfDataFile.java...

Thanks, looks good!

iklam · 2021-11-05T04:36:13Z

Thanks @plummercj @kevinjwalls @cl4es for the review. I filed https://bugs.openjdk.java.net/browse/JDK-8276687 to remove the JDK 1.4.1 support.
Passed Oracle CI tiers1-4
/integrate

openjdk · 2021-11-05T04:37:12Z

Going to push as commit 8e17ce0.
Since your change was applied there have been 51 commits pushed to the master branch:

396132f: 8275509: ModuleDescriptor.hashCode isn't reproducible across builds
9ad4d3d: 8276025: Hotspot's libsvml.so may conflict with user dependency
e21b5c7: 8276650: GenGraphs does not produce deterministic output
7b1916e: 8233557: [TESTBUG] DoubleClickTitleBarTest.java fails on macOs
8ec80c4: 8276653: Missing row headers in j.l.Character docs
7e87f94: 8276652: Missing row headers in MethodHandles.Lookup docs
dcf36f8: 8275670: ciReplay: java.lang.NoClassDefFoundError when trying to load java/lang/invoke/LambdaForm$MH
81203ef: 8276655: Use blessed modifier order in SCTP
2b5a32c: 8275718: Relax memory constraint on exception counter updates
99d4b07: 8276649: MethodHandles.Lookup docs: replace the table in the cross-module access check section with list
... and 41 more: https://git.openjdk.java.net/jdk/compare/495c828ae95205885b091dde795b517ba332a2b1...master

Your commit was automatically rebased without conflicts.

openjdk · 2021-11-05T04:37:31Z

@iklam Pushed as commit 8e17ce0.

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

sspitsyn · 2021-11-06T12:16:10Z

Hi Ioi,
Sorry for being late here.
Just to complete this...
Thank you for your answers! I'm okay with them.

iklam · 2021-11-06T16:46:27Z

Hi Ioi,
Sorry for being late here.
Just to complete this...
Thank you for your answers! I'm okay with them.

Thanks Serguei!

8275185: Remove dead code and clean up jvmstat LocalVmManager

c2f3937

openjdk bot added the serviceability serviceability-dev@openjdk.org label Oct 13, 2021

iklam marked this pull request as ready for review October 13, 2021 04:23

openjdk bot added the rfr Pull request is ready for review label Oct 13, 2021

plummercj reviewed Oct 19, 2021

View reviewed changes

@kevinjwalls and @plummercj review - (1) restore PerfDataFile.userDir…

77a386e

…NamePattern, etc. (2) Fixed comments

Merge branch 'master' into 8275185-jvmstat-LocalVmManager-cleanup-and…

bbeb7c1

…-remove-dead-code

plummercj approved these changes Nov 4, 2021

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label Nov 4, 2021

cl4es approved these changes Nov 4, 2021

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kevinjwalls approved these changes Nov 4, 2021

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openjdk bot closed this Nov 5, 2021

openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Nov 5, 2021

8275185: Remove dead code and clean up jvmstat LocalVmManager #5923

8275185: Remove dead code and clean up jvmstat LocalVmManager #5923

iklam commented Oct 13, 2021 •

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8275185: Remove dead code and clean up jvmstat LocalVmManager #5923

8275185: Remove dead code and clean up jvmstat LocalVmManager #5923

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