--- a/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.test/src/org/graalvm/compiler/core/test/GraalCompilerTest.java	Mon Jun 18 16:13:21 2018 +0200
+++ b/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.core.test/src/org/graalvm/compiler/core/test/GraalCompilerTest.java	Mon Jun 18 09:48:22 2018 -0700
@@ -41,14 +41,13 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.EnumMap;
-import java.util.HashMap;
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Supplier;
 
-import jdk.vm.ci.meta.JavaConstant;
 import org.graalvm.compiler.api.directives.GraalDirectives;
 import org.graalvm.compiler.api.replacements.SnippetReflectionProvider;
 import org.graalvm.compiler.api.test.Graal;
@@ -135,6 +134,7 @@
 import jdk.vm.ci.meta.Assumptions.Assumption;
 import jdk.vm.ci.meta.ConstantReflectionProvider;
 import jdk.vm.ci.meta.DeoptimizationReason;
+import jdk.vm.ci.meta.JavaConstant;
 import jdk.vm.ci.meta.JavaKind;
 import jdk.vm.ci.meta.JavaType;
 import jdk.vm.ci.meta.MetaAccessProvider;
@@ -882,7 +882,7 @@
         }
     }
 
-    private Map<ResolvedJavaMethod, InstalledCode> cache = new HashMap<>();
+    private Map<ResolvedJavaMethod, InstalledCode> cache = new ConcurrentHashMap<>();
 
     /**
      * Gets installed code for a given method, compiling it first if necessary. The graph is parsed
@@ -1075,7 +1075,7 @@
         return backend.createDefaultInstalledCode(debug, method, compilationResult);
     }
 
-    private final Map<ResolvedJavaMethod, Executable> methodMap = new HashMap<>();
+    private final Map<ResolvedJavaMethod, Executable> methodMap = new ConcurrentHashMap<>();
 
     /**
      * Converts a reflection {@link Method} to a {@link ResolvedJavaMethod}.