8351640: Print reason for making method not entrant #23980

shipilev · 2025-03-11T11:36:59Z

A simple quality of life improvement. We are studying compiler dynamics in Leyden, and it would be convenient to know why the particular methods are marked as not entrant. We just need to pass the extra string argument to nmethod::make_not_entrant and print it out.

Sample log excerpt for mainline:

$ grep com.sun.tools.javac.util.IntHashTable::lookup print-compilation.log 
987   780       3       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)
1019  877       4       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)
1024  780       3       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)   made not entrant: not used
4995  877       4       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)   made not entrant: uncommon trap
5287 3734       3       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)
6615 5472       4       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)
6626 3734       3       com.sun.tools.javac.util.IntHashTable::lookup (100 bytes)   made not entrant: not used

You can now clearly see the method lifecycle. 1 second in app lifetime, the method was initially compiled at level 3. Shortly after, it got compiled at level 4, turning level 3 method unused. 4 seconds later, level 4 method encountered uncommon trap, so we are back to level 3. After 1.3 seconds more, the final compilation at level 4 completed, and second level 3 compilation was removed as unused.

Additional testing:

Linux x86_64 server fastdebug, hotspot:tier1
Linux x86_64 server fastdebug, all

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Issue

JDK-8351640: Print reason for making method not entrant (Enhancement - P4)

Reviewers

Vladimir Kozlov (@vnkozlov - Reviewer) Review applies to 5003bf11
Vladimir Ivanov (@iwanowww - Reviewer)

Contributors

Vladimir Ivanov <vlivanov@openjdk.org>

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/23980/head:pull/23980
$ git checkout pull/23980

Update a local copy of the PR:
$ git checkout pull/23980
$ git pull https://git.openjdk.org/jdk.git pull/23980/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 23980

View PR using the GUI difftool:
$ git pr show -t 23980

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/23980.diff

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bridgekeeper · 2025-03-11T11:37:35Z

👋 Welcome back shade! 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 · 2025-03-11T11:37:40Z

@shipilev 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:

8351640: Print reason for making method not entrant

Co-authored-by: Vladimir Ivanov <vlivanov@openjdk.org>
Reviewed-by: vlivanov, kvn

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 9 new commits pushed to the master branch:

02c850f: 8350982: -server|-client causes fatal exception on static JDK
2371696: 8303770: Remove Baltimore root certificate expiring in May 2025
f16a742: 8351626: Update remaining icons to SVG format
a21fa46: 8351309: test/hotspot/jtreg/runtime/posixSig/TestPosixSig.java fails on static-jdk
3b189e0: 8351345: [IR Framework] Improve reported disabled IR verification messages
95b66d5: 8351700: Remove code conditional on BarrierSetNMethod being null
84f87dd: 8351665: Remove unused UseNUMA in os_aix.cpp
4be502e: 8350642: Interpreter: Upgrade CountBytecodes to 64 bit on 64 bit platforms
1fe4526: 8350194: Last 2 parameters of ReturnNode::ReturnNode are swapped in the declaration

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.

openjdk · 2025-03-11T11:38:16Z

@shipilev The following labels will be automatically applied to this pull request:

graal
hotspot

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

mlbridge · 2025-03-11T11:41:28Z

Webrevs

vnkozlov

Good.

src/hotspot/share/code/nmethod.cpp

iwanowww

Looks good.

Do you mind incorporating log compilation tool support? [1]

diff --git a/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/LogParser.java b/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/LogParser.java
index e1e305abe10..61cbc054200 100644
--- a/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/LogParser.java
+++ b/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/LogParser.java
@@ -1099,6 +1099,10 @@ public void startElement(String uri, String localName, String qname, Attributes
             e.setCompileKind(compileKind);
             String level = atts.getValue("level");
             e.setLevel(level);
+            String reason = atts.getValue("reason");
+            if (reason != null) {
+              e.setReason(reason);
+            }
             events.add(e);
         } else if (qname.equals("uncommon_trap")) {
             String id = atts.getValue("compile_id");
diff --git a/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/MakeNotEntrantEvent.java b/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/MakeNotEntrantEvent.java
index b4015537c74..d230f1b4336 100644
--- a/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/MakeNotEntrantEvent.java
+++ b/src/utils/LogCompilation/src/main/java/com/sun/hotspot/tools/compiler/MakeNotEntrantEvent.java
@@ -47,6 +47,11 @@ class MakeNotEntrantEvent extends BasicLogEvent {
      */
     private String level;
 
+    /**
+     * The reason of invalidation.
+     */
+    private String reason;
+
     /**
      * The compile kind.
      */
@@ -64,10 +69,14 @@ public NMethod getNMethod() {
 
     public void print(PrintStream stream, boolean printID) {
         if (isZombie()) {
-            stream.printf("%s make_zombie\n", getId());
+            stream.printf("%s make_zombie", getId());
         } else {
-            stream.printf("%s make_not_entrant\n", getId());
+            stream.printf("%s make_not_entrant", getId());
+        }
+        if (getReason() != null) {
+            stream.printf(": %s", getReason());
         }
+        stream.println();
     }
 
     public boolean isZombie() {
@@ -88,7 +97,21 @@ public void setLevel(String level) {
       this.level = level;
   }
 
-    /**
+  /**
+   * @return the reason
+   */
+  public String getReason() {
+      return reason;
+  }
+
+  /**
+   * @param reason the reason to set
+   */
+  public void setReason(String reason) {
+      this.reason = reason;
+  }
+
+  /**
    * @return the compileKind
    */
   public String getCompileKind() {

shipilev · 2025-03-12T17:35:35Z

Do you mind incorporating log compilation tool support? [1]

I don't mind, added. Looks like this still works:

$ cd src/tools/LogCompilation
$ make

shipilev · 2025-03-12T17:35:44Z

/contributor add @iwanowww

openjdk · 2025-03-12T17:35:54Z

@shipilev
Contributor Vladimir Ivanov <vlivanov@openjdk.org> successfully added.

iwanowww

Thanks. Looks good.

shipilev · 2025-03-12T18:14:10Z

Thanks! I'll integrate once GHA clears.

shipilev · 2025-03-12T19:44:42Z

/integrate

openjdk · 2025-03-12T19:45:31Z

Going to push as commit 930455b.
Since your change was applied there have been 11 commits pushed to the master branch:

895f64a: 8351142: Add JFR monitor deflation and statistics events
db531bf: 8351881: Tidy complains about missing "alt" attribute
02c850f: 8350982: -server|-client causes fatal exception on static JDK
2371696: 8303770: Remove Baltimore root certificate expiring in May 2025
f16a742: 8351626: Update remaining icons to SVG format
a21fa46: 8351309: test/hotspot/jtreg/runtime/posixSig/TestPosixSig.java fails on static-jdk
3b189e0: 8351345: [IR Framework] Improve reported disabled IR verification messages
95b66d5: 8351700: Remove code conditional on BarrierSetNMethod being null
84f87dd: 8351665: Remove unused UseNUMA in os_aix.cpp
4be502e: 8350642: Interpreter: Upgrade CountBytecodes to 64 bit on 64 bit platforms
... and 1 more: https://git.openjdk.org/jdk/compare/1d147ccb4cfcb1da23664ac941e56ac542a7ac61...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-03-12T19:45:39Z

@shipilev Pushed as commit 930455b.

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

shipilev added 2 commits March 11, 2025 11:56

Base version

00d421b

Use resource allocation for temp buffer

b13a108

openjdk bot added the rfr Pull request is ready for review label Mar 11, 2025

openjdk bot added graal graal-dev@openjdk.org hotspot hotspot-dev@openjdk.org labels Mar 11, 2025

vnkozlov approved these changes Mar 11, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Mar 11, 2025

iwanowww reviewed Mar 11, 2025

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src/hotspot/share/code/nmethod.cpp Show resolved Hide resolved

shipilev added 2 commits March 12, 2025 08:21

Merge branch 'master' into JDK-8351640-nmethod-not-entrant-reason

5003bf1

Add to LogCompilation as well

38491fb

openjdk bot removed the ready Pull request is ready to be integrated label Mar 12, 2025

iwanowww reviewed Mar 12, 2025

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Add LogCompilation support

5da9766

iwanowww approved these changes Mar 12, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Mar 12, 2025

openjdk bot added the integrated Pull request has been integrated label Mar 12, 2025

openjdk bot closed this Mar 12, 2025

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Mar 12, 2025

JohnTortugo mentioned this pull request Jun 9, 2025

8359064: Expose reason for marking nmethod non-entrant to JVMCI client #25706

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