diff --git a/java_indexer/lib/java-symbol-solver-core.jar b/java_indexer/lib/java-symbol-solver-core.jar
index 18562c83..3818af1e 100644
Binary files a/java_indexer/lib/java-symbol-solver-core.jar and b/java_indexer/lib/java-symbol-solver-core.jar differ
diff --git a/java_indexer/lib/java-symbol-solver-logic.jar b/java_indexer/lib/java-symbol-solver-logic.jar
index 2a01daa8..219eebf0 100644
Binary files a/java_indexer/lib/java-symbol-solver-logic.jar and b/java_indexer/lib/java-symbol-solver-logic.jar differ
diff --git a/java_indexer/lib/java-symbol-solver-model.jar b/java_indexer/lib/java-symbol-solver-model.jar
index 814428b1..ebcb497d 100644
Binary files a/java_indexer/lib/java-symbol-solver-model.jar and b/java_indexer/lib/java-symbol-solver-model.jar differ
diff --git a/java_indexer/src/main/java/com/sourcetrail/JavaIndexer.java b/java_indexer/src/main/java/com/sourcetrail/JavaIndexer.java
index 8153d876..424e4e56 100644
--- a/java_indexer/src/main/java/com/sourcetrail/JavaIndexer.java
+++ b/java_indexer/src/main/java/com/sourcetrail/JavaIndexer.java
@@ -3,25 +3,25 @@ package com.sourcetrail;
 import java.io.File;
 import java.io.IOException;
 import java.io.StringReader;
-import java.lang.String;
 import java.util.HashMap;
 import java.util.Map;
 
-import com.github.javaparser.ast.CompilationUnit;
-import com.github.javaparser.ast.PackageDeclaration;
 import com.github.javaparser.JavaParser;
 import com.github.javaparser.ParseProblemException;
 import com.github.javaparser.Position;
 import com.github.javaparser.Problem;
 import com.github.javaparser.Range;
+import com.github.javaparser.ast.CompilationUnit;
+import com.github.javaparser.ast.PackageDeclaration;
 import com.github.javaparser.symbolsolver.javaparser.Navigator;
 import com.github.javaparser.symbolsolver.javaparsermodel.JavaParserFacade;
 import com.github.javaparser.symbolsolver.model.resolution.TypeSolver;
 import com.github.javaparser.symbolsolver.resolution.typesolvers.CombinedTypeSolver;
 import com.github.javaparser.symbolsolver.resolution.typesolvers.JarTypeSolver;
-import com.github.javaparser.symbolsolver.resolution.typesolvers.JavaParserTypeSolver;
 import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeSolver;
 
+import com.sourcetrail.typesolver.SynchronizedJavaParserTypeSolver;
+
 public class JavaIndexer 
 {
 	private static Map<String, TypeSolver> typeSolvers = new HashMap<>();
@@ -37,36 +37,40 @@ public class JavaIndexer
 			CombinedTypeSolver combinedTypeSolver = new CombinedTypeSolver();
 
 			combinedTypeSolver.add(new ReflectionTypeSolver());
-			for (String path: classPath.split("\\;"))
+			
+			synchronized (typeSolvers)
 			{
-				if (typeSolvers.containsKey(path))
+				for (String path: classPath.split("\\;"))
 				{
-					combinedTypeSolver.add(typeSolvers.get(path));
-				}
-				else 
-				{
-					TypeSolver typeSolver = null;
-					
-					if (path.endsWith(".jar"))
+					if (typeSolvers.containsKey(path))
 					{
-						try
-						{
-							typeSolver = new JarTypeSolver(path);
-						}
-						catch (IOException e)
-						{
-							System.out.println("unable to add jar file: " + path);
-						}
+						combinedTypeSolver.add(typeSolvers.get(path));
 					}
-					else if (!path.isEmpty())
+					else 
 					{
-						typeSolver = new JavaParserTypeSolver(new File(path));
-					}
-					
-					if (typeSolver != null)
-					{
-						typeSolvers.put(path, typeSolver);
-						combinedTypeSolver.add(typeSolver);
+						TypeSolver typeSolver = null;
+						
+						if (path.endsWith(".jar"))
+						{
+							try
+							{
+								typeSolver = new JarTypeSolver(path);
+							}
+							catch (IOException e)
+							{
+								System.out.println("unable to add jar file: " + path);
+							}
+						}
+						else if (!path.isEmpty())
+						{
+							typeSolver = new SynchronizedJavaParserTypeSolver(new File(path));
+						}
+						
+						if (typeSolver != null)
+						{
+							typeSolvers.put(path, typeSolver);
+							combinedTypeSolver.add(typeSolver);
+						}
 					}
 				}
 			}
diff --git a/java_indexer/src/main/java/com/sourcetrail/typesolver/SynchronizedJavaParserTypeSolver.java b/java_indexer/src/main/java/com/sourcetrail/typesolver/SynchronizedJavaParserTypeSolver.java
new file mode 100644
index 00000000..b1dae652
--- /dev/null
+++ b/java_indexer/src/main/java/com/sourcetrail/typesolver/SynchronizedJavaParserTypeSolver.java
@@ -0,0 +1,53 @@
+package com.sourcetrail.typesolver;
+
+import java.io.File;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+import com.github.javaparser.symbolsolver.model.declarations.ReferenceTypeDeclaration;
+import com.github.javaparser.symbolsolver.model.resolution.SymbolReference;
+import com.github.javaparser.symbolsolver.resolution.typesolvers.JavaParserTypeSolver;
+
+public class SynchronizedJavaParserTypeSolver extends JavaParserTypeSolver
+{	
+	private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
+    private Map<String, SymbolReference<ReferenceTypeDeclaration>> solvedTypes = new HashMap<>();
+	
+	public SynchronizedJavaParserTypeSolver(File srcDir) 
+	{
+		super(srcDir);
+	}
+
+	@Override
+	public SymbolReference<ReferenceTypeDeclaration> tryToSolveType(String name) 
+	{
+		SymbolReference<ReferenceTypeDeclaration> solvedType = SymbolReference.unsolved(ReferenceTypeDeclaration.class);
+		
+		{
+			lock.readLock().lock();
+			if (solvedTypes.containsKey(name))
+			{
+				solvedType = solvedTypes.get(name);
+			}
+			lock.readLock().unlock();
+		}
+		
+		if (!solvedType.isSolved())
+		{
+			solvedType = super.tryToSolveType(name);
+			
+			if (solvedType.isSolved()) 
+			{
+				lock.writeLock().lock();
+				if (!solvedTypes.containsKey(name))
+				{
+					solvedTypes.put(name, solvedType);
+				}
+				lock.writeLock().unlock();
+			}
+		}
+		
+		return solvedType;
+	}
+}
diff --git a/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp b/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp
index 7dd4b769..488a4f16 100644
--- a/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp
+++ b/src/lib_java/data/parser/java/JavaEnvironmentFactory.cpp
@@ -53,6 +53,14 @@ void JavaEnvironmentFactory::createInstance(std::string classPath, std::string&
 	std::string classPathOption = "-Djava.class.path=" + classPath;
 	options[0].optionString = const_cast<char*>(classPathOption.c_str());
 	options[1].optionString = const_cast<char*>("-Xms64m");
+
+	// use these options to enable profiling in VisualVM
+	//options[2].optionString = const_cast<char*>("-Dcom.sun.management.jmxremote");
+	//options[3].optionString = const_cast<char*>("-Dcom.sun.management.jmxremote.port=9010");
+	//options[4].optionString = const_cast<char*>("-Dcom.sun.management.jmxremote.local.only=false");
+	//options[5].optionString = const_cast<char*>("-Dcom.sun.management.jmxremote.authenticate=false");
+	//options[6].optionString = const_cast<char*>("-Dcom.sun.management.jmxremote.ssl=false");
+
 	if (optionCount == 3)
 	{
 		options[2].optionString = const_cast<char*>(maximumMemoryOprionString.c_str());