fix memory leak of threads in single context mode

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/call/special/CallBinaryMethodNode.java

@@ -347,7 +347,7 @@ Object callMethodSingleContext(VirtualFrame frame, @SuppressWarnings("unused") P
     @Specialization(guards = {"func == cachedFunc", "builtinNode != null", "takesSelfArg",
                     "frame != null || unusedFrame"}, limit = "getCallSiteInlineCacheMaxDepth()", assumptions = "singleContextAssumption()")
     Object callSelfMethodSingleContext(VirtualFrame frame, @SuppressWarnings("unused") PBuiltinMethod func, Object arg1, Object arg2,
-                    @SuppressWarnings("unused") @Cached("func") PBuiltinMethod cachedFunc,
+                    @SuppressWarnings("unused") @Cached(value = "func", weak = true) PBuiltinMethod cachedFunc,
                     @SuppressWarnings("unused") @Cached("takesSelfArg(func)") boolean takesSelfArg,
                     @Cached("getTernary(frame, func.getFunction())") PythonTernaryBuiltinNode builtinNode,
                     @SuppressWarnings("unused") @Cached("frameIsUnused(builtinNode)") boolean unusedFrame) {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/call/special/CallQuaternaryMethodNode.java

@@ -81,7 +81,7 @@ Object call(VirtualFrame frame, @SuppressWarnings("unused") PBuiltinFunction fun
     @Specialization(guards = {"func == cachedFunc", "builtinNode != null", "!takesSelfArg",
                     "frame != null || unusedFrame"}, limit = "getCallSiteInlineCacheMaxDepth()", assumptions = "singleContextAssumption()")
     Object callMethodSingle(VirtualFrame frame, @SuppressWarnings("unused") PBuiltinMethod func, Object arg1, Object arg2, Object arg3, Object arg4,
-                    @SuppressWarnings("unused") @Cached("func") PBuiltinMethod cachedFunc,
+                    @SuppressWarnings("unused") @Cached(value = "func", weak = true) PBuiltinMethod cachedFunc,
                     @SuppressWarnings("unused") @Cached("takesSelfArg(func)") boolean takesSelfArg,
                     @Cached("getQuaternary(frame, func.getFunction())") PythonQuaternaryBuiltinNode builtinNode,
                     @SuppressWarnings("unused") @Cached("frameIsUnused(builtinNode)") boolean unusedFrame) {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/call/special/CallTernaryMethodNode.java

@@ -211,7 +211,7 @@ static Object doBuiltinMethodCtCached(VirtualFrame frame, @SuppressWarnings("unu
     @Specialization(guards = {"func == cachedFunc", "builtinNode != null", "takesSelfArg",
                     "frame != null || unusedFrame"}, limit = "getCallSiteInlineCacheMaxDepth()", assumptions = "singleContextAssumption()")
     static Object callSelfMethodSingleContext(VirtualFrame frame, @SuppressWarnings("unused") PBuiltinMethod func, Object arg1, Object arg2, Object arg3,
-                    @SuppressWarnings("unused") @Cached("func") PBuiltinMethod cachedFunc,
+                    @SuppressWarnings("unused") @Cached(value = "func", weak = true) PBuiltinMethod cachedFunc,
                     @SuppressWarnings("unused") @Cached("takesSelfArg(func)") boolean takesSelfArg,
                     @Cached("getQuaternary(frame, func.getFunction())") PythonQuaternaryBuiltinNode builtinNode,
                     @SuppressWarnings("unused") @Cached("frameIsUnused(builtinNode)") boolean unusedFrame) {

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/nodes/call/special/CallUnaryMethodNode.java

@@ -225,7 +225,7 @@ Object callMethodSingleContext(VirtualFrame frame, @SuppressWarnings("unused") P
     @Specialization(guards = {"func == cachedFunc", "builtinNode != null", "takesSelfArg",
                     "frame != null || unusedFrame"}, limit = "getCallSiteInlineCacheMaxDepth()", assumptions = "singleContextAssumption()")
     Object callSelfMethodSingleContext(VirtualFrame frame, @SuppressWarnings("unused") PBuiltinMethod func, Object arg,
-                    @SuppressWarnings("unused") @Cached("func") PBuiltinMethod cachedFunc,
+                    @SuppressWarnings("unused") @Cached(value = "func", weak = true) PBuiltinMethod cachedFunc,
                     @SuppressWarnings("unused") @Cached("takesSelfArg(func)") boolean takesSelfArg,
                     @Cached("getBinary(frame, func.getFunction())") PythonBinaryBuiltinNode builtinNode,
                     @SuppressWarnings("unused") @Cached("frameIsUnused(builtinNode)") boolean unusedFrame) {