### Eclipse Workspace Patch 1.0
#P jackrabbit-core
Index: src/main/java/org/apache/jackrabbit/core/TransactionContext.java
===================================================================
--- src/main/java/org/apache/jackrabbit/core/TransactionContext.java	(revision 814512)
+++ src/main/java/org/apache/jackrabbit/core/TransactionContext.java	(working copy)
@@ -350,6 +350,6 @@
      */
     public static boolean isCurrentXid(Xid xid, boolean fallback) {
         Xid currentXid = (Xid) CURRENT_XID.get();
-        return fallback ? true : (currentXid == null || xid == null) ? fallback : Arrays.equals(xid.getGlobalTransactionId(), currentXid.getGlobalTransactionId());  
+        return (currentXid == null || xid == null) ? fallback : Arrays.equals(xid.getGlobalTransactionId(), currentXid.getGlobalTransactionId());  
     }
 }
Index: src/main/java/org/apache/jackrabbit/core/state/DefaultISMLocking.java
===================================================================
--- src/main/java/org/apache/jackrabbit/core/state/DefaultISMLocking.java	(revision 899564)
+++ src/main/java/org/apache/jackrabbit/core/state/DefaultISMLocking.java	(working copy)
@@ -44,7 +44,7 @@
      * The internal read-write lock.
      */
     private final RWLock rwLock = new RWLock();
-
+    
     /**
      * {@inheritDoc}
      */
@@ -61,8 +61,15 @@
         return new WriteLock() {
 
             {
-                rwLock.writeLock().acquire();
-                rwLock.setActiveXid(TransactionContext.getCurrentXid());
+            	// sync Block to prevent race conditions
+            	synchronized (this) {
+                	// Mark on the rwLock the current Xid to handle Thread-Deadlocks in XA Environment
+                	Xid currentXid = TransactionContext.getCurrentXid();
+                	rwLock.markCurrentXid(currentXid);
+                    rwLock.writeLock().acquire();
+                    // After we got a writeLock we will set the ActiveXid
+                    rwLock.setActiveXid(currentXid);
+				}
             }
 
             /**
@@ -103,16 +110,25 @@
     private static final class RWLock extends ReentrantWriterPreferenceReadWriteLock {
 
         private Xid activeXid;
+        private Xid markedXid;
 
         /**
          * Allow reader when there is no active writer, or current thread owns
          * the write lock (reentrant).
          */
         protected boolean allowReader() {
-            return TransactionContext.isCurrentXid(activeXid, (activeWriter_ == null || activeWriter_ == Thread.currentThread()));
+        	return TransactionContext.isCurrentXid(activeXid, (activeWriter_ == null || activeWriter_ == Thread.currentThread()));
         }
 
         /**
+         * Set the Xid to mark it on this RWLock
+         * @param xid
+         */
+        public void markCurrentXid(Xid xid) {
+        	markedXid = xid;
+		}
+
+		/**
          * Sets the active Xid
          * @param xid
          */
@@ -120,7 +136,8 @@
             if (activeXid != null && xid != null) {
                 boolean sameGTI = Arrays.equals(activeXid.getGlobalTransactionId(), xid.getGlobalTransactionId());
                 if (!sameGTI) {
-                    log.warn("Unable to set the ActiveXid while a other one is associated with a different GloalTransactionId with this RWLock.");
+                    log.warn("Unable to set the ActiveXid while a other one is associated with a different GlobalTransactionId with this RWLock. " +
+                    		"Please file a Jira Issue if you see this message and refer to JCR-1334.");
                     return;
                 }
             }
@@ -135,9 +152,9 @@
         protected synchronized Signaller endWrite() {
             --writeHolds_;
             if (writeHolds_ > 0) {  // still being held
-                return null;
+            	return null;
             } else {
-                activeXid = null;
+            	activeXid = null;
                 activeWriter_ = null;
                 if (waitingReaders_ > 0 && allowReader()) {
                     return readerLock_;
@@ -148,5 +165,33 @@
                 }
             }
         }
+
+        /**
+         * {@inheritDoc}
+         * 
+         * If there is still a activeXid with a other GlobalTransactionId startWrite will not be allowed
+         */  
+        protected synchronized boolean startWrite() {
+        	// Test if we have a activeXid or a markedXid. If not check the activeWriter Thread 
+        	boolean allow = TransactionContext.isCurrentXid((activeXid != null) ? activeXid : markedXid, (activeWriter_ == Thread.currentThread()));
+            if (allow) {
+            	++writeHolds_;
+            	if (activeWriter_ == null) {
+            		// Set the ActiveWriter to hold it .. could happen if we are in XA Environment
+            		activeWriter_ = Thread.currentThread();
+            	}
+                return true;
+            } else if (writeHolds_ == 0) {
+            	if (activeReaders_ == 0 || (readers_.size() == 1 && readers_.get(Thread.currentThread()) != null)) {
+            		activeWriter_ = Thread.currentThread();
+            		writeHolds_ = 1;
+            		return true;
+            	} else {
+            		return false;
+            	}
+            } else {
+            	return false;
+            }
+        }	
     }
 }