Subject: [PATCH] NamePool locking behavior improvements
---
Index: src/main/java/net/sf/saxon/om/NamePool.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
diff --git a/src/main/java/net/sf/saxon/om/NamePool.java b/src/main/java/net/sf/saxon/om/NamePool.java
--- a/src/main/java/net/sf/saxon/om/NamePool.java	(revision 497a9f0a7549279d890f1f49cd5002320869bf9f)
+++ b/src/main/java/net/sf/saxon/om/NamePool.java	(date 1726698522394)
@@ -76,7 +76,7 @@
 
     private final ConcurrentHashMap<NamespaceUri, String> suggestedPrefixes = new ConcurrentHashMap<>();
 
-
+    private final Object fingerprintGuard = new Object();
 
 
 
@@ -163,8 +163,8 @@
      * for the same name with a prefix equal to "".
      */
     
-    public synchronized int allocateFingerprint(NamespaceUri uri, String local) {
-        if (NamespaceUri.isReserved(uri) || NamespaceUri.SAXON.equals(uri)) {
+    public int allocateFingerprint(NamespaceUri uri, String local) {
+        if (!uri.equals(NamespaceUri.NULL) && (NamespaceUri.isReserved(uri) || NamespaceUri.SAXON.equals(uri))) {
             int fp = StandardNames.getFingerprint(uri, local);
             if (fp != -1) {
                 return fp;
@@ -175,17 +175,23 @@
         if (existing >= 0) {
             return existing;
         }
-        long nextUnique = unique.getAndIncrement();
-        if (nextUnique > MAX_FINGERPRINT) {
-            throw new NamePoolLimitException("Too many distinct names in NamePool");
-        }
-        int next = (int)nextUnique;
-        Integer existing2 = qNameToInteger.putIfAbsent(qName, next);
-        if (keyWasAbsent(existing2)) {
-            integerToQName.put(next, qName);
-            return next;
-        } else {
-            return existing;
+        synchronized (fingerprintGuard) {
+            existing = qNameToInteger.getOrDefault(qName, -1);
+            if (existing >= 0) {
+                return existing;
+            }
+            long nextUnique = unique.getAndIncrement();
+            if (nextUnique > MAX_FINGERPRINT) {
+                throw new NamePoolLimitException("Too many distinct names in NamePool");
+            }
+            int next = (int) nextUnique;
+            Integer existing2 = qNameToInteger.putIfAbsent(qName, next);
+            if (keyWasAbsent(existing2)) {
+                integerToQName.put(next, qName);
+                return next;
+            } else {
+                return existing;
+            }
         }
     }