Index: lucene/analysis/common/src/java/org/apache/lucene/analysis/util/AnalysisSPILoader.java
===================================================================
--- lucene/analysis/common/src/java/org/apache/lucene/analysis/util/AnalysisSPILoader.java	(revision 1449874)
+++ lucene/analysis/common/src/java/org/apache/lucene/analysis/util/AnalysisSPILoader.java	(working copy)
@@ -66,7 +66,7 @@
    * <p><em>This method is expensive and should only be called for discovery
    * of new service providers on the given classpath/classloader!</em>
    */
-  public void reload(ClassLoader classloader) {
+  public synchronized void reload(ClassLoader classloader) {
     final SPIClassIterator<S> loader = SPIClassIterator.get(clazz, classloader);
     final LinkedHashMap<String,Class<? extends S>> services = new LinkedHashMap<String,Class<? extends S>>();
     while (loader.hasNext()) {
Index: lucene/core/src/java/org/apache/lucene/util/NamedSPILoader.java
===================================================================
--- lucene/core/src/java/org/apache/lucene/util/NamedSPILoader.java	(revision 1449874)
+++ lucene/core/src/java/org/apache/lucene/util/NamedSPILoader.java	(working copy)
@@ -53,7 +53,7 @@
    * <p><em>This method is expensive and should only be called for discovery
    * of new service providers on the given classpath/classloader!</em>
    */
-  public void reload(ClassLoader classloader) {
+  public synchronized void reload(ClassLoader classloader) {
     final LinkedHashMap<String,S> services = new LinkedHashMap<String,S>(this.services);
     final SPIClassIterator<S> loader = SPIClassIterator.get(clazz, classloader);
     while (loader.hasNext()) {