a concurrency enhancement which was not used because tests showed worse

indexing speed. I leave the code there since it may be useful in
SolrCloud environments.

source/net/yacy/cora/federate/solr/connector/ConcurrentUpdateSolrConnector.java

@@ -94,8 +94,8 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
                         String id = (String) doc.getFieldValue(CollectionSchema.id.getSolrFieldName());
                         Metadata md = AbstractSolrConnector.getMetadata(doc);
                         updateCache(id, md);
-                        for (int i = 0; i < getmore; i++) {
-                            SolrInputDocument d = ConcurrentUpdateSolrConnector.this.updateQueue.take();
+                        SolrInputDocument d;
+                        while (getmore-- > 0 && (d = ConcurrentUpdateSolrConnector.this.updateQueue.poll()) != null) {
                             if (d == POISON_DOCUMENT) {
                                 ConcurrentUpdateSolrConnector.this.updateQueue.put(POISON_DOCUMENT); // make sure that the outer loop terminates as well
                                 break;
@@ -150,7 +150,8 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
     private ARH<String> missCache;
     private BlockingQueue<SolrInputDocument> updateQueue;
     private BlockingQueue<String> deleteQueue;
-    private Thread deletionHandler, updateHandler;
+    private Thread deletionHandler;
+    private Thread[] updateHandler;
     
     public ConcurrentUpdateSolrConnector(SolrConnector connector, int updateCapacity, int idCacheCapacity, int concurrency) {
         this.connector = connector;
@@ -266,11 +267,26 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
     }
     
     public void ensureAliveUpdateHandler() {
-        if (this.updateHandler == null || !this.updateHandler.isAlive()) {
-            this.updateHandler = new Thread(new UpdateHandler());
-            this.updateHandler.setName(this.getClass().getName() + "_UpdateHandler");
-            this.updateHandler.start();
+        if (this.updateHandler == null) {
+            this.updateHandler = new Thread[1/*Runtime.getRuntime().availableProcessors()*/];
         }
+        for (int i = 0; i < this.updateHandler.length; i++) {
+            if (this.updateHandler[i] == null || !this.updateHandler[i].isAlive()) {
+                this.updateHandler[i] = new Thread(new UpdateHandler());
+                this.updateHandler[i].setName(this.getClass().getName() + "_UpdateHandler_" + i);
+                this.updateHandler[i].start();
+            }
+        }
+    }
+    
+    public boolean anyUpdateHandlerAlive() {
+        if (this.updateHandler == null) {
+            return false;
+        }
+        for (int i = 0; i < this.updateHandler.length; i++) {
+            if (this.updateHandler[i] != null && this.updateHandler[i].isAlive()) return true;
+        }
+        return false;
     }
     
     @Override
@@ -323,7 +339,7 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
         ensureAliveUpdateHandler();
         try {this.updateQueue.put(POISON_DOCUMENT);} catch (final InterruptedException e) {}
         try {this.deletionHandler.join();} catch (final InterruptedException e) {}
-        try {this.updateHandler.join();} catch (final InterruptedException e) {}
+        for (Thread t: this.updateHandler) try {t.join();} catch (final InterruptedException e) {}
         this.connector.close();
         this.metadataCache.clear();
         this.connector = null;
@@ -335,7 +351,7 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
         this.deleteQueue.clear();
         this.updateQueue.clear();
         try {this.updateQueue.put(POISON_DOCUMENT);} catch (final InterruptedException e) {}
-        try {this.updateHandler.join();} catch (final InterruptedException e) {}
+        for (Thread t: this.updateHandler) try {t.join();} catch (final InterruptedException e) {}
         this.connector.clear();
         this.metadataCache.clear();
     }
@@ -397,7 +413,7 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
         String id = (String) solrdoc.getFieldValue(CollectionSchema.id.getSolrFieldName());
         removeIdFromDeleteQueue(id);
         updateCache(id, AbstractSolrConnector.getMetadata(solrdoc));
-        if (this.updateHandler.isAlive()) {
+        if (anyUpdateHandlerAlive()) {
             try {this.updateQueue.put(solrdoc);} catch (final InterruptedException e) {}
         } else {
             this.connector.add(solrdoc);
@@ -411,7 +427,7 @@ public class ConcurrentUpdateSolrConnector implements SolrConnector {
             removeIdFromDeleteQueue(id);
             updateCache(id, AbstractSolrConnector.getMetadata(doc));
         }
-        if (this.updateHandler.isAlive()) {
+        if (anyUpdateHandlerAlive()) {
             for (SolrInputDocument doc: solrdocs) try {this.updateQueue.put(doc);} catch (final InterruptedException e) {}
         } else {
             this.connector.add(solrdocs);