From e9f43826748b4aebea1683b38e1775c88971f571 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 10:56:28 +0100
Subject: [PATCH 01/12] clear local ref in JavaObjectHolder

---
 Sources/SwiftJava/JavaObjectHolder.swift | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Sources/SwiftJava/JavaObjectHolder.swift b/Sources/SwiftJava/JavaObjectHolder.swift
index 65557e23..e6d0ca28 100644
--- a/Sources/SwiftJava/JavaObjectHolder.swift
+++ b/Sources/SwiftJava/JavaObjectHolder.swift
@@ -26,6 +26,12 @@ public final class JavaObjectHolder {
   public init(object: jobject, environment: JNIEnvironment) {
     self.object = environment.interface.NewGlobalRef(environment, object)
     self.environment = environment
+
+    // If we are taking over a local ref, let's delete that.
+    let refType = environment.interface.GetObjectRefType(environment, object)
+    if refType == JNILocalRefType {
+      environment.interface.DeleteLocalRef(environment, object)
+    }
   }
 
   /// Forget this Java object, meaning that it is no longer used from anywhere

From e5733df5725ce0b98ba4a2034195ded408731f87 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 10:56:55 +0100
Subject: [PATCH 02/12] cleanup localref in JNI cache

---
 Sources/SwiftJavaRuntimeSupport/_JNIMethodIDCache.swift | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Sources/SwiftJavaRuntimeSupport/_JNIMethodIDCache.swift b/Sources/SwiftJavaRuntimeSupport/_JNIMethodIDCache.swift
index 3b9cecc8..4ba4c541 100644
--- a/Sources/SwiftJavaRuntimeSupport/_JNIMethodIDCache.swift
+++ b/Sources/SwiftJavaRuntimeSupport/_JNIMethodIDCache.swift
@@ -63,6 +63,7 @@ public final class _JNIMethodIDCache: Sendable {
     let clazz: jobject
     if let jniClass = environment.interface.FindClass(environment, className) {
       clazz = environment.interface.NewGlobalRef(environment, jniClass)!
+      environment.interface.DeleteLocalRef(environment, jniClass)
       self.javaObjectHolder = nil
     } else {
       // Clear any ClassNotFound exceptions from FindClass

From d995929582e1f32ef9be60e57ce67b32e6f0e9ca Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 11:00:48 +0100
Subject: [PATCH 03/12] delete local refs when doing method lookups

---
 Sources/SwiftJava/JavaObject+MethodCalls.swift | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Sources/SwiftJava/JavaObject+MethodCalls.swift b/Sources/SwiftJava/JavaObject+MethodCalls.swift
index 1e86792b..f1e68a14 100644
--- a/Sources/SwiftJava/JavaObject+MethodCalls.swift
+++ b/Sources/SwiftJava/JavaObject+MethodCalls.swift
@@ -108,6 +108,7 @@ extension AnyJavaObject {
     let thisClass = try environment.translatingJNIExceptions {
       environment.interface.GetObjectClass(environment, javaThis)
     }!
+    defer { environment.interface.DeleteLocalRef(environment, thisClass) }
 
     return try environment.translatingJNIExceptions {
       try Self.javaMethodLookup(
@@ -131,6 +132,7 @@ extension AnyJavaObject {
     let thisClass = try environment.translatingJNIExceptions {
       environment.interface.GetObjectClass(environment, javaThis)
     }!
+    defer { environment.interface.DeleteLocalRef(environment, thisClass) }
 
     return try environment.translatingJNIExceptions {
       try Self.javaMethodLookup(
@@ -285,6 +287,7 @@ extension AnyJavaObject {
 
     // Retrieve the Java class instance from the object.
     let thisClass = environment.interface.GetObjectClass(environment, this)!
+    defer { environment.interface.DeleteLocalRef(environment, thisClass) }
 
     return environment.interface.GetFieldID(environment, thisClass, fieldName, FieldType.jniMangling)
   }

From a386a15fdd7a586f3cab0d638dff4931f516de0b Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 12:54:46 +0100
Subject: [PATCH 04/12] make frame count based on args

---
 .../SwiftJava/JavaObject+MethodCalls.swift    | 30 ++++++++++++++++---
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/Sources/SwiftJava/JavaObject+MethodCalls.swift b/Sources/SwiftJava/JavaObject+MethodCalls.swift
index f1e68a14..9275a459 100644
--- a/Sources/SwiftJava/JavaObject+MethodCalls.swift
+++ b/Sources/SwiftJava/JavaObject+MethodCalls.swift
@@ -155,7 +155,11 @@ extension AnyJavaObject {
   ) throws -> Result {
     // Retrieve the method that performs this call, then package the values and
     // call it.
+    // Size the frame to 1 ref per argument (strings/objects each need 1;
+    // primitives need 0, so this slightly over-estimates) plus 1 for the result ref.
     let jniMethod = Result.jniMethodCall(in: environment)
+    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each args) + 2))
+    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each args, in: environment)
     let jniResult = try environment.translatingJNIExceptions {
       jniMethod(environment, this, method, jniArgs)
@@ -221,7 +225,10 @@ extension AnyJavaObject {
   ) throws {
     // Retrieve the method that performs this call, then package the arguments
     // and call it.
+    // Size the frame to 1 ref per argument; no result ref needed for void calls.
     let jniMethod = environment.interface.CallVoidMethodA!
+    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each args) + 1))
+    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each args, in: environment)
     try environment.translatingJNIExceptions {
       jniMethod(environment, this, method, jniArgs)
@@ -271,11 +278,16 @@ extension AnyJavaObject {
         in: environment
       )
 
-      // Retrieve the constructor, then map the arguments and call it.
+      // Retrieve the constructor, then map the arguments and call it. Use a local
+      // frame so args are freed; promote the new object to the outer frame
+      // via PopLocalFrame(result).
+      // Size the frame to 1 ref per argument; result is promoted via PopLocalFrame(newObj).
+      environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each arguments) + 1))
       let jniArgs = getJValues(repeat each arguments, in: environment)
-      return try environment.translatingJNIExceptions {
+      let newObj = try environment.translatingJNIExceptions {
         environment.interface.NewObjectA!(environment, thisClass, methodID, jniArgs)
       }!
+      return environment.interface.PopLocalFrame(environment, newObj)!
     }
   }
 
@@ -309,6 +321,9 @@ extension AnyJavaObject {
 
       let fieldID = getJNIFieldID(fieldName, fieldType: fieldType)!
       let jniMethod = FieldType.jniFieldSet(in: environment)
+      // Frame of 2: 1 for the field value's local ref, 1 buffer.
+      environment.interface.PushLocalFrame(environment, 2)
+      defer { environment.interface.PopLocalFrame(environment, nil) }
       jniMethod(environment, javaThis, fieldID, newValue.getJNIValue(in: environment))
     }
   }
@@ -340,8 +355,12 @@ extension JavaClass {
       )
     }!
 
-    // Retrieve the method that performs this call, then
+    // Retrieve the method that performs this call, then package the values and
+    // call it.
+    // Size the frame to 1 ref per argument plus 1 for the result ref.
     let jniMethod = Result.jniStaticMethodCall(in: environment)
+    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each arguments) + 2))
+    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each arguments, in: environment)
     let jniResult = try environment.translatingJNIExceptions {
       jniMethod(environment, thisClass, methodID, jniArgs)
@@ -374,8 +393,11 @@ extension JavaClass {
       )
     }!
 
-    // Retrieve the method that performs this call, then
+    // Retrieve the method that performs this call
+    // Size the frame to 1 ref per argument; no result ref needed for void calls.
     let jniMethod = environment.interface.CallStaticVoidMethodA
+    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each arguments) + 1))
+    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each arguments, in: environment)
     try environment.translatingJNIExceptions {
       jniMethod!(environment, thisClass, methodID, jniArgs)

From 8e491cd9831866f217c86ce46973f05bc7c35e73 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 12:54:59 +0100
Subject: [PATCH 05/12] more small cleanups

---
 .../JNI/JNISwift2JavaGenerator+NativeTranslation.swift          | 1 +
 Sources/JavaKit/Helpers/_JNIMethodIDCache.swift                 | 2 ++
 Sources/SwiftJava/Exceptions/ExceptionHandling.swift            | 1 +
 3 files changed, 4 insertions(+)

diff --git a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+NativeTranslation.swift b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+NativeTranslation.swift
index 599808fb..b3e39d67 100644
--- a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+NativeTranslation.swift
+++ b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+NativeTranslation.swift
@@ -1293,6 +1293,7 @@ extension JNISwift2JavaGenerator {
           """
           let class$ = environment.interface.GetObjectClass(environment, \(placeholder))
           let methodID$ = environment.interface.GetMethodID(environment, class$, "apply", "\(methodSignature.mangledName)")!
+          environment.interface.DeleteLocalRef(environment, class$)
           let arguments$: [jvalue] = [\(arguments.joined(separator: ", "))]
           """
         )
diff --git a/Sources/JavaKit/Helpers/_JNIMethodIDCache.swift b/Sources/JavaKit/Helpers/_JNIMethodIDCache.swift
index 31c6a2c0..a54e547b 100644
--- a/Sources/JavaKit/Helpers/_JNIMethodIDCache.swift
+++ b/Sources/JavaKit/Helpers/_JNIMethodIDCache.swift
@@ -46,6 +46,8 @@ public final class _JNIMethodIDCache: Sendable {
         fatalError("Method \(method.signature) with signature \(method.signature) not found in class \(className)")
       }
     }
+    // clazz is still needed by GetMethodID above; delete the local ref only after reduce completes.
+    environment.interface.DeleteLocalRef(environment, clazz)
   }
 
   public subscript(_ method: Method) -> jmethodID? {
diff --git a/Sources/SwiftJava/Exceptions/ExceptionHandling.swift b/Sources/SwiftJava/Exceptions/ExceptionHandling.swift
index 55d676b3..d78533cd 100644
--- a/Sources/SwiftJava/Exceptions/ExceptionHandling.swift
+++ b/Sources/SwiftJava/Exceptions/ExceptionHandling.swift
@@ -54,6 +54,7 @@ extension JNIEnvironment {
       }
       return
     }
+    defer { self.interface.DeleteLocalRef(self, exceptionClass) }
 
     _ = interface.ThrowNew(self, exceptionClass, javaException.message ?? "")
   }

From ce785da7688fe3b215ffe20e47074ce5197ff186 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 13:17:19 +0100
Subject: [PATCH 06/12] fix tests

---
 Tests/JExtractSwiftTests/JNI/JNIClosureTests.swift | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Tests/JExtractSwiftTests/JNI/JNIClosureTests.swift b/Tests/JExtractSwiftTests/JNI/JNIClosureTests.swift
index 8cab76f0..841420d7 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIClosureTests.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIClosureTests.swift
@@ -70,6 +70,7 @@ struct JNIClosureTests {
           SwiftModule.emptyClosure(closure: {
             let class$ = environment.interface.GetObjectClass(environment, closure)
             let methodID$ = environment.interface.GetMethodID(environment, class$, "apply", "()V")!
+            environment.interface.DeleteLocalRef(environment, class$)
             let arguments$: [jvalue] = []
             environment.interface.CallVoidMethodA(environment, closure, methodID$, arguments$)
           }
@@ -127,6 +128,7 @@ struct JNIClosureTests {
           SwiftModule.closureWithArgumentsAndReturn(closure: { _0, _1 in
             let class$ = environment.interface.GetObjectClass(environment, closure)
             let methodID$ = environment.interface.GetMethodID(environment, class$, "apply", "(JZ)J")!
+            environment.interface.DeleteLocalRef(environment, class$)
             let arguments$: [jvalue] = [_0.getJValue(in: environment), _1.getJValue(in: environment)]
             return Int64(fromJNI: environment.interface.CallLongMethodA(environment, closure, methodID$, arguments$), in: environment)
           }

From c702ebd1821d9ccbea908b2e64b1d98eda877022 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Thu, 12 Mar 2026 16:01:42 +0100
Subject: [PATCH 07/12] protocol wrappers emit a frame

---
 .../JNISwift2JavaGenerator+SwiftThunkPrinting.swift | 13 +++++++++++++
 Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift |  6 ++++++
 2 files changed, 19 insertions(+)

diff --git a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
index 0f2ab299..15027fab 100644
--- a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
+++ b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
@@ -171,6 +171,19 @@ extension JNISwift2JavaGenerator {
     }
 
     printer.printBraceBlock(function.swiftDecl.signatureString) { printer in
+      // Push a local JNI frame so refs created during this upcall are freed on exit.
+      // When called from a Swift async context (e.g. cooperative thread pool) there is
+      // no enclosing JNI frame, so refs would otherwise accumulate indefinitely. When
+      // called from a Java-initiated native call there is already a frame, but pushing
+      // a sub-frame still frees refs earlier and prevents overflow within a single call.
+      let paramCount = function.originalFunctionSignature.parameters.count
+      printer.print(
+        """
+        let environment$ = try! JavaVirtualMachine.shared().environment()
+        environment$.interface.PushLocalFrame(environment$, \(paramCount * 2 + 4))
+        defer { environment$.interface.PopLocalFrame(environment$, nil) }
+        """
+      )
       var upcallArguments = zip(
         function.originalFunctionSignature.parameters,
         function.parameterConversions
diff --git a/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift b/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift
index 0c504693..06f19647 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift
@@ -315,9 +315,15 @@ struct JNIProtocolTests {
         """
         extension SwiftJavaSomeProtocolWrapper {
           public func method() {
+            let environment$ = try! JavaVirtualMachine.shared().environment()
+            environment$.interface.PushLocalFrame(environment$, 4)
+            defer { environment$.interface.PopLocalFrame(environment$, nil) }
             _javaSomeProtocolInterface.method()
           }
           public func withObject(c: SomeClass) -> SomeClass {
+            let environment$ = try! JavaVirtualMachine.shared().environment()
+            environment$.interface.PushLocalFrame(environment$, 6)
+            defer { environment$.interface.PopLocalFrame(environment$, nil) }
             let cClass = try! JavaClass<JavaSomeClass>(environment: JavaVirtualMachine.shared().environment())
             let cPointer = UnsafeMutablePointer<SomeClass>.allocate(capacity: 1)
             cPointer.initialize(to: c)

From 430119518b4d42eb5360c685793af85b0178cb7e Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Mon, 16 Mar 2026 15:34:50 +0100
Subject: [PATCH 08/12] try running tests on android

---
 .github/workflows/pull_request.yml | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 46acd6b5..aca2b7d8 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -281,3 +281,12 @@ jobs:
         run: ./scripts/run-linkage-test.sh
         env:
           JAVA_HOME: ${{ env.JAVA_HOME }}
+
+  android-sdk-testing:
+    name: Android SDK with emulator testing
+    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@0.0.8
+    with:
+      enable_linux_checks: false
+      enable_windows_checks: false
+      enable_android_sdk_build: true
+      enable_android_sdk_checks: true
\ No newline at end of file

From c960adb4432024015a20bab40e0bd9115f75cbc3 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Tue, 17 Mar 2026 08:24:08 +0100
Subject: [PATCH 09/12] remove android test again

---
 .github/workflows/pull_request.yml | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index aca2b7d8..a94188a9 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -280,13 +280,4 @@ jobs:
       - name: Run linkage test
         run: ./scripts/run-linkage-test.sh
         env:
-          JAVA_HOME: ${{ env.JAVA_HOME }}
-
-  android-sdk-testing:
-    name: Android SDK with emulator testing
-    uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@0.0.8
-    with:
-      enable_linux_checks: false
-      enable_windows_checks: false
-      enable_android_sdk_build: true
-      enable_android_sdk_checks: true
\ No newline at end of file
+          JAVA_HOME: ${{ env.JAVA_HOME }}
\ No newline at end of file

From 3f126bf5f75a658c7669013a06587de441846113 Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Tue, 17 Mar 2026 09:07:14 +0100
Subject: [PATCH 10/12] use new frame helpers

---
 ...ift2JavaGenerator+SwiftThunkPrinting.swift | 54 +++++++++----------
 .../JNI/JNIProtocolTests.swift                | 26 ++++-----
 2 files changed, 39 insertions(+), 41 deletions(-)

diff --git a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
index 15027fab..b13ac55e 100644
--- a/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
+++ b/Sources/JExtractSwiftLib/JNI/JNISwift2JavaGenerator+SwiftThunkPrinting.swift
@@ -171,43 +171,41 @@ extension JNISwift2JavaGenerator {
     }
 
     printer.printBraceBlock(function.swiftDecl.signatureString) { printer in
+      let resultType = function.originalFunctionSignature.result.type
+      let returnStmt = !resultType.isVoid ? "return " : ""
+      // If the protocol function is non-throwing, we have no option but to force try.
+      // The error thrown by `withLocalFrame` is an OOM error anyway.
+      let withLocalFrameTryKeyword = function.originalFunctionSignature.isThrowing ? "try" : "try!"
+
       // Push a local JNI frame so refs created during this upcall are freed on exit.
       // When called from a Swift async context (e.g. cooperative thread pool) there is
       // no enclosing JNI frame, so refs would otherwise accumulate indefinitely. When
       // called from a Java-initiated native call there is already a frame, but pushing
       // a sub-frame still frees refs earlier and prevents overflow within a single call.
       let paramCount = function.originalFunctionSignature.parameters.count
-      printer.print(
-        """
-        let environment$ = try! JavaVirtualMachine.shared().environment()
-        environment$.interface.PushLocalFrame(environment$, \(paramCount * 2 + 4))
-        defer { environment$.interface.PopLocalFrame(environment$, nil) }
-        """
-      )
-      var upcallArguments = zip(
-        function.originalFunctionSignature.parameters,
-        function.parameterConversions
-      ).map { param, conversion in
-        // Wrap-java does not extract parameter names, so no labels
-        conversion.render(&printer, param.parameterName!)
-      }
+      let estimatedRefCount = paramCount * 2 + 4
+      printer.print("let environment$ = try! JavaVirtualMachine.shared().environment()")
+      printer.printBraceBlock("\(returnStmt)\(withLocalFrameTryKeyword) environment$.withLocalFrame(capacity: \(estimatedRefCount))") { printer in
+        var upcallArguments = zip(
+          function.originalFunctionSignature.parameters,
+          function.parameterConversions
+        ).map { param, conversion in
+          // Wrap-java does not extract parameter names, so no labels
+          conversion.render(&printer, param.parameterName!)
+        }
 
-      // If the underlying translated method requires
-      // a SwiftArena, we pass in the global arena
-      if translatedDecl.translatedFunctionSignature.requiresSwiftArena {
-        upcallArguments.append("JavaSwiftArena.defaultAutoArena")
-      }
+        // If the underlying translated method requires
+        // a SwiftArena, we pass in the global arena
+        if translatedDecl.translatedFunctionSignature.requiresSwiftArena {
+          upcallArguments.append("JavaSwiftArena.defaultAutoArena")
+        }
 
-      let tryClause = function.originalFunctionSignature.isThrowing ? "try " : ""
-      let javaUpcall =
-        "\(tryClause)\(wrapper.javaInterfaceVariableName).\(function.swiftFunctionName)(\(upcallArguments.joined(separator: ", ")))"
+        let tryClause = function.originalFunctionSignature.isThrowing ? "try " : ""
+        let javaUpcall =
+          "\(tryClause)\(wrapper.javaInterfaceVariableName).\(function.swiftFunctionName)(\(upcallArguments.joined(separator: ", ")))"
 
-      let resultType = function.originalFunctionSignature.result.type
-      let result = function.resultConversion.render(&printer, javaUpcall)
-      if resultType.isVoid {
-        printer.print(result)
-      } else {
-        printer.print("return \(result)")
+        let result = function.resultConversion.render(&printer, javaUpcall)
+        printer.print("\(returnStmt)\(result)")
       }
     }
   }
diff --git a/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift b/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift
index 06f19647..526c8967 100644
--- a/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift
+++ b/Tests/JExtractSwiftTests/JNI/JNIProtocolTests.swift
@@ -316,23 +316,23 @@ struct JNIProtocolTests {
         extension SwiftJavaSomeProtocolWrapper {
           public func method() {
             let environment$ = try! JavaVirtualMachine.shared().environment()
-            environment$.interface.PushLocalFrame(environment$, 4)
-            defer { environment$.interface.PopLocalFrame(environment$, nil) }
-            _javaSomeProtocolInterface.method()
+            try! environment$.withLocalFrame(capacity: 4) {
+              _javaSomeProtocolInterface.method()
+            }
           }
           public func withObject(c: SomeClass) -> SomeClass {
             let environment$ = try! JavaVirtualMachine.shared().environment()
-            environment$.interface.PushLocalFrame(environment$, 6)
-            defer { environment$.interface.PopLocalFrame(environment$, nil) }
-            let cClass = try! JavaClass<JavaSomeClass>(environment: JavaVirtualMachine.shared().environment())
-            let cPointer = UnsafeMutablePointer<SomeClass>.allocate(capacity: 1)
-            cPointer.initialize(to: c)
-            guard let unwrapped$ = _javaSomeProtocolInterface.withObject(cClass.wrapMemoryAddressUnsafe(Int64(Int(bitPattern: cPointer))), JavaSwiftArena.defaultAutoArena) else {
-              fatalError("Upcall to withObject unexpectedly returned nil")
+            return try! environment$.withLocalFrame(capacity: 6) {
+              let cClass = try! JavaClass<JavaSomeClass>(environment: JavaVirtualMachine.shared().environment())
+              let cPointer = UnsafeMutablePointer<SomeClass>.allocate(capacity: 1)
+              cPointer.initialize(to: c)
+              guard let unwrapped$ = _javaSomeProtocolInterface.withObject(cClass.wrapMemoryAddressUnsafe(Int64(Int(bitPattern: cPointer))), JavaSwiftArena.defaultAutoArena) else {
+                fatalError("Upcall to withObject unexpectedly returned nil")
+              }
+              let result$MemoryAddress$ = unwrapped$.as(JavaJNISwiftInstance.self)!.memoryAddress()
+              let result$Pointer = UnsafeMutablePointer<SomeClass>(bitPattern: Int(result$MemoryAddress$))!
+              return result$Pointer.pointee
             }
-            let result$MemoryAddress$ = unwrapped$.as(JavaJNISwiftInstance.self)!.memoryAddress()
-            let result$Pointer = UnsafeMutablePointer<SomeClass>(bitPattern: Int(result$MemoryAddress$))!
-            return result$Pointer.pointee
           }
         }
         """,

From d66be7fe21b001410b97789818a7ba31ec59936f Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Tue, 17 Mar 2026 09:07:30 +0100
Subject: [PATCH 11/12] remove usages of explicit frames in method calls

---
 .../SwiftJava/JavaObject+MethodCalls.swift    | 27 +------------------
 1 file changed, 1 insertion(+), 26 deletions(-)

diff --git a/Sources/SwiftJava/JavaObject+MethodCalls.swift b/Sources/SwiftJava/JavaObject+MethodCalls.swift
index 9275a459..c7523c69 100644
--- a/Sources/SwiftJava/JavaObject+MethodCalls.swift
+++ b/Sources/SwiftJava/JavaObject+MethodCalls.swift
@@ -155,11 +155,7 @@ extension AnyJavaObject {
   ) throws -> Result {
     // Retrieve the method that performs this call, then package the values and
     // call it.
-    // Size the frame to 1 ref per argument (strings/objects each need 1;
-    // primitives need 0, so this slightly over-estimates) plus 1 for the result ref.
     let jniMethod = Result.jniMethodCall(in: environment)
-    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each args) + 2))
-    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each args, in: environment)
     let jniResult = try environment.translatingJNIExceptions {
       jniMethod(environment, this, method, jniArgs)
@@ -225,10 +221,7 @@ extension AnyJavaObject {
   ) throws {
     // Retrieve the method that performs this call, then package the arguments
     // and call it.
-    // Size the frame to 1 ref per argument; no result ref needed for void calls.
     let jniMethod = environment.interface.CallVoidMethodA!
-    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each args) + 1))
-    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each args, in: environment)
     try environment.translatingJNIExceptions {
       jniMethod(environment, this, method, jniArgs)
@@ -278,16 +271,10 @@ extension AnyJavaObject {
         in: environment
       )
 
-      // Retrieve the constructor, then map the arguments and call it. Use a local
-      // frame so args are freed; promote the new object to the outer frame
-      // via PopLocalFrame(result).
-      // Size the frame to 1 ref per argument; result is promoted via PopLocalFrame(newObj).
-      environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each arguments) + 1))
       let jniArgs = getJValues(repeat each arguments, in: environment)
-      let newObj = try environment.translatingJNIExceptions {
+      return try environment.translatingJNIExceptions {
         environment.interface.NewObjectA!(environment, thisClass, methodID, jniArgs)
       }!
-      return environment.interface.PopLocalFrame(environment, newObj)!
     }
   }
 
@@ -321,9 +308,6 @@ extension AnyJavaObject {
 
       let fieldID = getJNIFieldID(fieldName, fieldType: fieldType)!
       let jniMethod = FieldType.jniFieldSet(in: environment)
-      // Frame of 2: 1 for the field value's local ref, 1 buffer.
-      environment.interface.PushLocalFrame(environment, 2)
-      defer { environment.interface.PopLocalFrame(environment, nil) }
       jniMethod(environment, javaThis, fieldID, newValue.getJNIValue(in: environment))
     }
   }
@@ -355,12 +339,7 @@ extension JavaClass {
       )
     }!
 
-    // Retrieve the method that performs this call, then package the values and
-    // call it.
-    // Size the frame to 1 ref per argument plus 1 for the result ref.
     let jniMethod = Result.jniStaticMethodCall(in: environment)
-    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each arguments) + 2))
-    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each arguments, in: environment)
     let jniResult = try environment.translatingJNIExceptions {
       jniMethod(environment, thisClass, methodID, jniArgs)
@@ -393,11 +372,7 @@ extension JavaClass {
       )
     }!
 
-    // Retrieve the method that performs this call
-    // Size the frame to 1 ref per argument; no result ref needed for void calls.
     let jniMethod = environment.interface.CallStaticVoidMethodA
-    environment.interface.PushLocalFrame(environment, Int32(countArgs(repeat each arguments) + 1))
-    defer { environment.interface.PopLocalFrame(environment, nil) }
     let jniArgs = getJValues(repeat each arguments, in: environment)
     try environment.translatingJNIExceptions {
       jniMethod!(environment, thisClass, methodID, jniArgs)

From 02a407e3bb5441e675bdc48742c2ed60ace7215a Mon Sep 17 00:00:00 2001
From: Mads Odgaard <mads.odgaard@frameo.com>
Date: Tue, 17 Mar 2026 09:08:15 +0100
Subject: [PATCH 12/12] fix yaml format

---
 .github/workflows/pull_request.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index a94188a9..46acd6b5 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -280,4 +280,4 @@ jobs:
       - name: Run linkage test
         run: ./scripts/run-linkage-test.sh
         env:
-          JAVA_HOME: ${{ env.JAVA_HOME }}
\ No newline at end of file
+          JAVA_HOME: ${{ env.JAVA_HOME }}