--- loci/common/Location.java.orig	2011-01-28 02:48:36.000000000 +0100
+++ loci/common/Location.java	2011-01-28 03:36:55.000000000 +0100
@@ -55,7 +55,12 @@
   // -- Static fields --
 
   /** Map from given filenames to actual filenames. */
-  private static HashMap<String, Object> idMap = new HashMap<String, Object>();
+  private static ThreadLocal<HashMap<String, Object>> 
+      idMap = new ThreadLocal<HashMap<String, Object>>() {
+          protected HashMap<String, Object> initialValue() {
+              return new HashMap<String, Object>();
+          }
+      };
 
   // -- Fields --
 
@@ -105,16 +110,16 @@
    */
   public static void mapId(String id, String filename) {
     if (id == null) return;
-    if (filename == null) idMap.remove(id);
-    else idMap.put(id, filename);
+    if (filename == null) getIdMap().remove(id);
+    else getIdMap().put(id, filename);
     LOGGER.debug("Location.mapId: {} -> {}", id, filename);
   }
 
   /** Maps the given id to the given IRandomAccess object. */
   public static void mapFile(String id, IRandomAccess ira) {
     if (id == null) return;
-    if (ira == null) idMap.remove(id);
-    else idMap.put(id, ira);
+    if (ira == null) getIdMap().remove(id);
+    else getIdMap().put(id, ira);
     LOGGER.debug("Location.mapFile: {} -> {}", id, ira);
   }
 
@@ -128,26 +133,26 @@
    * @see #mapId(String, String)
    */
   public static String getMappedId(String id) {
-    if (idMap == null) return id;
+    if (getIdMap() == null) return id;
     String filename = null;
-    if (id != null && (idMap.get(id) instanceof String)) {
-      filename = (String) idMap.get(id);
+    if (id != null && (getIdMap().get(id) instanceof String)) {
+      filename = (String) getIdMap().get(id);
     }
     return filename == null ? id : filename;
   }
 
   /** Gets the random access handle for the given id. */
   public static IRandomAccess getMappedFile(String id) {
-    if (idMap == null) return null;
+    if (getIdMap() == null) return null;
     IRandomAccess ira = null;
-    if (id != null && (idMap.get(id) instanceof IRandomAccess)) {
-      ira = (IRandomAccess) idMap.get(id);
+    if (id != null && (getIdMap().get(id) instanceof IRandomAccess)) {
+      ira = (IRandomAccess) getIdMap().get(id);
     }
     return ira;
   }
 
   /** Return the id mapping. */
-  public static HashMap<String, Object> getIdMap() { return idMap; }
+  public static HashMap<String, Object> getIdMap() { return idMap.get(); }
 
   /**
    * Set the id mapping using the given HashMap.
@@ -156,7 +161,7 @@
    */
   public static void setIdMap(HashMap<String, Object> map) {
     if (map == null) throw new IllegalArgumentException("map cannot be null");
-    idMap = map;
+    idMap.set(map);
   }
 
   /**