[java] Deadlock when executing PMD in multiple threads

**Affects PMD Version:** 

7.7.0, 7.6.0
probably all releases in recent time

**Description:**

We are executing the following on a multi-Maven project:
``mvn -B test pmd:check -P pmd -DskipTests``

Which causes a deadlock on some machines:
![MvnPMDDeadlock](https://github.com/user-attachments/assets/0e4ae1b2-131e-4d56-b27f-bdc08863f40a)

The problem is likely caused by some unfortunate CPU situation that only occurs on certain machines with certain code and is therefore extremely difficult to reproduce.

<details><summary>Summary from the <a href="https://issues.apache.org/jira/browse/MPMD-408">initial maven issue</a></summary>

> **michael-o**
> Does a downgrade help?

> **AB-xdev**
> @ michael-o
> I'm currently checking the exact cause as we got a ton of Maven plugin updates over the weekend.
> Maybe also one of those broke it...

> **AB-xdev** 
> Okay my conclusions so far: This is probably not related to the PMD version
>
> I downgraded to a state before the update and the same error also occurs randomly.
> I was unable to reproduce or find the problem ín any of our ~50 CIs so this must be caused either by
> * Windows
> * hardware configuration
> * anti-virus solution
>
> However as of now I think this is a hardware configuration based problem:
>
> * The problem also occurred with disabled anti-virus
> * I checked with a colleague which has nearly the same hardware as I but a different Windows version (10/11) and it also happened on his machine:
> ![screenshot-1](https://github.com/user-attachments/assets/beb0140e-ccf9-411f-a650-9ec765048b12)
> Doing some further testing with thread configurations now...

> **AB-xdev**
> I was able to reproduce the problem with different maven parallelization/thread configurations (-T8, -T1, ...) on the same machine but not on others.
> The amount of spawned PMD threads does NOT depend on the selected maven parallelization and is ALWAYS the same amount as CPU threads ([Runtime.getRuntime().availableProcessors()](https://github.com/pmd/pmd/blob/4473aa666754f888ace372ec3d5ca183f6e0af23/pmd-core/src/main/java/net/sourceforge/pmd/PMDConfiguration.java#L100)).
> It's likely some unfortunate CPU situation that only occurs on certain machines with certain code.
>
>I inspected another [Threaddump](https://github.com/user-attachments/files/17542449/Threaddump2.txt) further and as far as i can tell the problem is a legitimate PMD problem.
> It looks like multiple threads are started for analysis, which process different classes/pieces of code and walk through related code.
> While they are being processed the threads (sometimes) lock each other, resulting in a deadlock:
>
> Example from the Threaddump:
> ```
> Thread #1: Class A (locked) -> ... -> Class C (waits for lock from Thread #16)
> Thread #16: Class C (locked) -> Class A (waits for lock from Thread #1)
> → Deadlock
> ```
>
> (for more details see the deadlock section at the end of the attached Thread dump)

</details>

The key finding from the Maven-Plugin issue is:

>I inspected another [Threaddump](https://github.com/user-attachments/files/17542449/Threaddump2.txt) further and as far as i can tell the problem is a legitimate PMD problem.
> It looks like multiple threads are started for analysis, which process different classes/pieces of code and walk through related code.
> While they are being processed the threads (sometimes) lock each other, resulting in a deadlock:
>
> Example from the Threaddump:
> ```
> Thread #1: Class A (locked) -> ... -> Class C (waits for lock from Thread #16)
> Thread #16: Class C (locked) -> Class A (waits for lock from Thread #1)
> → Deadlock
> ```

**Exception Stacktrace:**

<details><summary>Deadlock in Threaddump</summary>

```
Found one Java-level deadlock:
=============================
"PmdThread 1":
  waiting to lock monitor 0x0000025c81905b70 (object 0x000000041088f710, a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1),
  which is held by "PmdThread 16"

"PmdThread 16":
  waiting to lock monitor 0x0000025c8024f840 (object 0x0000000410800000, a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1),
  which is held by "PmdThread 1"

Java stack information for the threads listed above:
===================================================
"PmdThread 1":
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.getFinalStatus(ParseLock.java:28)
        - waiting to lock <0x000000041088f710> (a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.ensureParsed(ParseLock.java:22)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.ensureParsed(GenericSigBase.java:76)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.getTypeParams(GenericSigBase.java:92)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ClassStub.getTypeParameters(ClassStub.java:314)
        at net.sourceforge.pmd.lang.java.symbols.JTypeParameterOwnerSymbol.getTypeParameterCount(JTypeParameterOwnerSymbol.java:47)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.typeArgsAreOk(ClassTypeImpl.java:446)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.validateParams(ClassTypeImpl.java:420)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.<init>(ClassTypeImpl.java:69)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.<init>(ClassTypeImpl.java:64)
        at net.sourceforge.pmd.lang.java.types.TypeSystem.parameterise(TypeSystem.java:530)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser$TypeScanner.makeClassType(TypeSigParser.java:364)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.classType(TypeSigParser.java:164)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeSignature(TypeSigParser.java:148)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeSignature(TypeSigParser.java:124)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeArg(TypeSigParser.java:209)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeArgsOpt(TypeSigParser.java:184)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.classType(TypeSigParser.java:162)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.classHeader(TypeSigParser.java:33)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser$$Lambda/0x0000025c38548448.parse(Unknown Source)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser.parseFully(SignatureParser.java:100)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser.parseClassSignature(SignatureParser.java:57)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$LazyClassSignature.doParse(GenericSigBase.java:155)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1.doParse(GenericSigBase.java:54)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.getFinalStatus(ParseLock.java:33)
        - locked <0x000000041088f8a0> (a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.ensureParsed(ParseLock.java:22)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.ensureParsed(GenericSigBase.java:76)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.getTypeParams(GenericSigBase.java:92)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ClassStub.getTypeParameters(ClassStub.java:314)
        at net.sourceforge.pmd.lang.java.symbols.JTypeParameterOwnerSymbol.getTypeParameterCount(JTypeParameterOwnerSymbol.java:47)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.typeArgsAreOk(ClassTypeImpl.java:446)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.validateParams(ClassTypeImpl.java:420)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.<init>(ClassTypeImpl.java:69)
        at net.sourceforge.pmd.lang.java.types.ClassTypeImpl.<init>(ClassTypeImpl.java:64)
        at net.sourceforge.pmd.lang.java.types.TypeSystem.parameterise(TypeSystem.java:530)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser$TypeScanner.makeClassType(TypeSigParser.java:364)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.classType(TypeSigParser.java:164)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeSignature(TypeSigParser.java:148)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeSignature(TypeSigParser.java:124)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeArg(TypeSigParser.java:209)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.typeArgsOpt(TypeSigParser.java:184)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.classType(TypeSigParser.java:162)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.TypeSigParser.classHeader(TypeSigParser.java:39)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser$$Lambda/0x0000025c38548448.parse(Unknown Source)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser.parseFully(SignatureParser.java:100)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser.parseClassSignature(SignatureParser.java:57)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$LazyClassSignature.doParse(GenericSigBase.java:155)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1.doParse(GenericSigBase.java:54)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.getFinalStatus(ParseLock.java:33)
        - locked <0x0000000410800000> (a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.ensureParsed(ParseLock.java:22)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.ensureParsed(GenericSigBase.java:76)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.getTypeParams(GenericSigBase.java:92)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ClassStub.getTypeParameters(ClassStub.java:314)
        at net.sourceforge.pmd.lang.java.symbols.JTypeParameterOwnerSymbol.getTypeParameterCount(JTypeParameterOwnerSymbol.java:47)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$DisambigVisitor.postProcess(AstDisambiguationPass.java:219)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$DisambigVisitor.visit(AstDisambiguationPass.java:189)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$DisambigVisitor.visit(AstDisambiguationPass.java:80)
        at net.sourceforge.pmd.lang.java.ast.ASTClassType.acceptVisitor(ASTClassType.java:157)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass.lambda$disambigWithCtx$0(AstDisambiguationPass.java:58)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$$Lambda/0x0000025c38546508.accept(Unknown Source)
        at java.util.Iterator.forEachRemaining(java.base@21.0.5/Iterator.java:133)
        at net.sourceforge.pmd.lang.ast.internal.IteratorBasedNStream.forEach(IteratorBasedNStream.java:102)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass.disambigWithCtx(AstDisambiguationPass.java:58)
        at net.sourceforge.pmd.lang.java.ast.InternalApiBridge.disambigWithCtx(InternalApiBridge.java:77)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymTableFactory.disambig(SymTableFactory.java:103)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visitTypeDecl(SymbolTableResolver.java:293)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visitTypeDecl(SymbolTableResolver.java:138)
        at net.sourceforge.pmd.lang.java.ast.JavaVisitorBase.visit(JavaVisitorBase.java:57)
        at net.sourceforge.pmd.lang.java.ast.ASTClassDeclaration.acceptVisitor(ASTClassDeclaration.java:38)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.ast.AstVisitorBase.visitChildren(AstVisitorBase.java:31)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visit(SymbolTableResolver.java:247)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visit(SymbolTableResolver.java:138)
        at net.sourceforge.pmd.lang.java.ast.ASTCompilationUnit.acceptVisitor(ASTCompilationUnit.java:109)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.traverse(SymbolTableResolver.java:164)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver.traverse(SymbolTableResolver.java:101)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.lambda$process$1(JavaAstProcessor.java:132)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor$$Lambda/0x0000025c38534cc0.run(Unknown Source)
        at net.sourceforge.pmd.benchmark.TimeTracker.bench(TimeTracker.java:163)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.process(JavaAstProcessor.java:132)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.process(JavaAstProcessor.java:166)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.process(JavaAstProcessor.java:150)
        at net.sourceforge.pmd.lang.java.ast.JavaParser.parseImpl(JavaParser.java:69)
        at net.sourceforge.pmd.lang.java.ast.JavaParser.parseImpl(JavaParser.java:25)
        at net.sourceforge.pmd.lang.ast.impl.javacc.JjtreeParserAdapter.parse(JjtreeParserAdapter.java:36)
        at net.sourceforge.pmd.lang.impl.PmdRunnable.parse(PmdRunnable.java:112)
        at net.sourceforge.pmd.lang.impl.PmdRunnable.processSource(PmdRunnable.java:132)
        at net.sourceforge.pmd.lang.impl.PmdRunnable.run(PmdRunnable.java:80)
        at java.util.concurrent.Executors$RunnableAdapter.call(java.base@21.0.5/Executors.java:572)
        at java.util.concurrent.FutureTask.run(java.base@21.0.5/FutureTask.java:317)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@21.0.5/ThreadPoolExecutor.java:1144)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@21.0.5/ThreadPoolExecutor.java:642)
        at java.lang.Thread.runWith(java.base@21.0.5/Thread.java:1596)
        at java.lang.Thread.run(java.base@21.0.5/Thread.java:1583)
"PmdThread 16":
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.getFinalStatus(ParseLock.java:28)
        - waiting to lock <0x0000000410800000> (a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.ensureParsed(ParseLock.java:22)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.ensureParsed(GenericSigBase.java:76)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.getTypeParams(GenericSigBase.java:92)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ClassStub.getTypeParameters(ClassStub.java:314)
        at net.sourceforge.pmd.lang.java.symbols.JTypeParameterOwnerSymbol.getLexicalScope(JTypeParameterOwnerSymbol.java:42)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ClassStub.getLexicalScope(ClassStub.java:326)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.getEnclosingTypeParams(GenericSigBase.java:72)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser.typeParamsWrapper(SignatureParser.java:88)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.SignatureParser.parseClassSignature(SignatureParser.java:56)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$LazyClassSignature.doParse(GenericSigBase.java:155)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1.doParse(GenericSigBase.java:54)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.getFinalStatus(ParseLock.java:33)
        - locked <0x000000041088f710> (a net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase$1)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ParseLock.ensureParsed(ParseLock.java:22)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.ensureParsed(GenericSigBase.java:76)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.GenericSigBase.getTypeParams(GenericSigBase.java:92)
        at net.sourceforge.pmd.lang.java.symbols.internal.asm.ClassStub.getTypeParameters(ClassStub.java:314)
        at net.sourceforge.pmd.lang.java.symbols.JTypeParameterOwnerSymbol.getTypeParameterCount(JTypeParameterOwnerSymbol.java:47)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$DisambigVisitor.postProcess(AstDisambiguationPass.java:219)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$DisambigVisitor.visit(AstDisambiguationPass.java:164)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$DisambigVisitor.visit(AstDisambiguationPass.java:80)
        at net.sourceforge.pmd.lang.java.ast.ASTClassType.acceptVisitor(ASTClassType.java:157)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass.lambda$disambigWithCtx$0(AstDisambiguationPass.java:58)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass$$Lambda/0x0000025c38546508.accept(Unknown Source)
        at net.sourceforge.pmd.lang.ast.internal.SingletonNodeStream.forEach(SingletonNodeStream.java:87)
        at net.sourceforge.pmd.lang.java.ast.AstDisambiguationPass.disambigWithCtx(AstDisambiguationPass.java:58)
        at net.sourceforge.pmd.lang.java.ast.InternalApiBridge.disambigWithCtx(InternalApiBridge.java:77)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymTableFactory.disambig(SymTableFactory.java:103)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visit(SymbolTableResolver.java:188)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visit(SymbolTableResolver.java:138)
        at net.sourceforge.pmd.lang.java.ast.ASTClassType.acceptVisitor(ASTClassType.java:157)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.ast.AstVisitorBase.visitChildren(AstVisitorBase.java:31)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.setTopSymbolTableAndVisitAllChildren(SymbolTableResolver.java:741)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visitMethodOrCtor(SymbolTableResolver.java:326)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visitMethodOrCtor(SymbolTableResolver.java:138)
        at net.sourceforge.pmd.lang.java.ast.JavaVisitorBase.visit(JavaVisitorBase.java:39)
        at net.sourceforge.pmd.lang.java.ast.ASTMethodDeclaration.acceptVisitor(ASTMethodDeclaration.java:59)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.ast.AstVisitorBase.visitChildren(AstVisitorBase.java:31)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visitTypeDecl(SymbolTableResolver.java:296)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visitTypeDecl(SymbolTableResolver.java:138)
        at net.sourceforge.pmd.lang.java.ast.JavaVisitorBase.visit(JavaVisitorBase.java:57)
        at net.sourceforge.pmd.lang.java.ast.ASTClassDeclaration.acceptVisitor(ASTClassDeclaration.java:38)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.ast.AstVisitorBase.visitChildren(AstVisitorBase.java:31)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visit(SymbolTableResolver.java:247)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.visit(SymbolTableResolver.java:138)
        at net.sourceforge.pmd.lang.java.ast.ASTCompilationUnit.acceptVisitor(ASTCompilationUnit.java:109)
        at net.sourceforge.pmd.lang.java.ast.AbstractJavaNode.acceptVisitor(AbstractJavaNode.java:38)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver$MyVisitor.traverse(SymbolTableResolver.java:164)
        at net.sourceforge.pmd.lang.java.symbols.table.internal.SymbolTableResolver.traverse(SymbolTableResolver.java:101)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.lambda$process$1(JavaAstProcessor.java:132)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor$$Lambda/0x0000025c38534cc0.run(Unknown Source)
        at net.sourceforge.pmd.benchmark.TimeTracker.bench(TimeTracker.java:163)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.process(JavaAstProcessor.java:132)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.process(JavaAstProcessor.java:166)
        at net.sourceforge.pmd.lang.java.internal.JavaAstProcessor.process(JavaAstProcessor.java:150)
        at net.sourceforge.pmd.lang.java.ast.JavaParser.parseImpl(JavaParser.java:69)
        at net.sourceforge.pmd.lang.java.ast.JavaParser.parseImpl(JavaParser.java:25)
        at net.sourceforge.pmd.lang.ast.impl.javacc.JjtreeParserAdapter.parse(JjtreeParserAdapter.java:36)
        at net.sourceforge.pmd.lang.impl.PmdRunnable.parse(PmdRunnable.java:112)
        at net.sourceforge.pmd.lang.impl.PmdRunnable.processSource(PmdRunnable.java:132)
        at net.sourceforge.pmd.lang.impl.PmdRunnable.run(PmdRunnable.java:80)
        at java.util.concurrent.Executors$RunnableAdapter.call(java.base@21.0.5/Executors.java:572)
        at java.util.concurrent.FutureTask.run(java.base@21.0.5/FutureTask.java:317)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@21.0.5/ThreadPoolExecutor.java:1144)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@21.0.5/ThreadPoolExecutor.java:642)
        at java.lang.Thread.runWith(java.base@21.0.5/Thread.java:1596)
        at java.lang.Thread.run(java.base@21.0.5/Thread.java:1583)

Found 1 deadlock.
```

</details>

from [Threaddump2.txt](https://github.com/user-attachments/files/17542449/Threaddump2.txt) (recommended dump)

Here a a few thread-dumps:
[Threaddump.txt](https://github.com/user-attachments/files/17542447/Threaddump.txt)
[Threaddump_colleague.txt](https://github.com/user-attachments/files/17542448/Threaddump_colleague.txt)

**Steps to reproduce:**

Reproducing the bug is next to impossible, I could only do so on machines with similar hardware.
However here are a few steps that can be followed:

1. Get a more complex maven project that uses PMD
2. Run  ``mvn -B test pmd:check -P pmd -DskipTests `` (maybe also with ``-T2C``) with an insanely high CPU count: ``-XX:ActiveProcessorCount=64``

**Workaround**

It's not possible to change the amount of spawned PMD threads from the Maven Plugin.
However one can manually lower that number to one thread by adding ``-XX:ActiveProcessorCount=1``. 
That way the check works reliable but it's really slow and it might also affect other parts of the build negatively.

**Running PMD through:** *Maven*

Java version: 21.0.5, vendor: Eclipse Adoptium
aka OpenJDK Runtime Environment Temurin-21.0.5+11 (build 21.0.5+11-LTS)
Apache Maven 3.9.9 (8e8579a9e76f7d015ee5ec7bfcdc97d260186937)
Windows 10 & 11
CPU: AMD Ryzen 3700X (8C/16T)
Private Multi Maven Project with around 15 modules and 30k LoC

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[java] Deadlock when executing PMD in multiple threads #5293

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