src/java.base/share/classes/jdk/internal/loader/BuiltinClassLoader.java

@@ -55,12 +55,13 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.jar.Attributes;
 import java.util.jar.Manifest;
 import java.util.stream.Stream;
 
-import jdk.internal.module.ModulePatcher.PatchedModuleReader;
 import jdk.internal.misc.VM;
+import jdk.internal.module.ModulePatcher.PatchedModuleReader;
+import jdk.internal.module.SystemModules;
 
 
 /**
  * The platform or application class loader. Resources loaded from modules
  * defined to the boot class loader are also loaded via an instance of this

@@ -133,11 +134,11 @@
     }
 
 
     // maps package name to loaded module for modules in the boot layer
     private static final Map<String, LoadedModule> packageToModule
-        = new ConcurrentHashMap<>(1024);
+        = new ConcurrentHashMap<>(SystemModules.PACKAGES_IN_BOOT_LAYER);
 
     // maps a module name to a module reference
     private final Map<String, ModuleReference> nameToModule;
 
     // maps a module reference to a module reader

@@ -920,11 +921,11 @@
 
     /**
      * Returns the ModuleReader for the given module.
      */
     private ModuleReader moduleReaderFor(ModuleReference mref) {
-        return moduleToReader.computeIfAbsent(mref, m -> createModuleReader(mref));
+        return moduleToReader.computeIfAbsent(mref, m -> createModuleReader(m));
     }
 
     /**
      * Creates a ModuleReader for the given module.
      */