bad hack to prevent a bug appearing in solr

defaults/solr/solrconfig.xml

@@ -125,8 +125,9 @@
        solr.RAMDirectoryFactory is memory based, not
        persistent, and doesn't work with replication.
     -->
-  <directoryFactory name="DirectoryFactory" 
-                    class="${solr.directoryFactory:solr.StandardDirectoryFactory}"/>
+  <!-- <directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.StandardDirectoryFactory}"/> -->
+  <!-- for solr.MMapDirectoryFactory see: https://issues.apache.org/jira/browse/SOLR-2247 -->
+  <directoryFactory name="DirectoryFactory" class="${solr.directoryFactory:solr.MMapDirectoryFactory}"/>
 
   <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        Index Config - These settings control low-level behavior of indexing

source/net/yacy/cora/services/federated/solr/AbstractSolrConnector.java

@@ -198,19 +198,22 @@ public class AbstractSolrConnector implements SolrConnector {
 
         // query the server
         //SearchResult result = new SearchResult(count);
-        try {
-            final QueryResponse rsp = this.server.query( query );
-            final SolrDocumentList docs = rsp.getResults();
-            return docs;
-            // add the docs into the YaCy search result container
-            /*
-            for (SolrDocument doc: docs) {
-                result.put(element)
+        Throwable error = null; // well this is a bad hack; see https://issues.apache.org/jira/browse/LUCENE-2239
+        // also: https://issues.apache.org/jira/browse/SOLR-2247
+        // we might try also: $JAVA_OPTS -Dsolr.directoryFactory=solr.MMapDirectoryFactory
+        for (int retry = 30; retry > 0; retry--) {
+            try {
+                final QueryResponse rsp = this.server.query(query);
+                final SolrDocumentList docs = rsp.getResults();
+                if (error != null) Log.logWarning("AbstractSolrConnector", "produced search result by silently ignoring an error before, message = " + error.getMessage());
+                return docs;
+            } catch (final Throwable e) {
+                Log.logWarning("AbstractSolrConnection", "problem with query=" + querystring, e);
+                error = e;
+                continue;
             }
-            */
-        } catch (final Throwable e) {
-            throw new IOException(e);
         }
+        throw new IOException(error.getMessage(), error);
     }
 
     /**
@@ -230,15 +233,23 @@ public class AbstractSolrConnector implements SolrConnector {
         query.setStart(0);
 
         // query the server
-        try {
-            final QueryResponse rsp = this.server.query( query );
-            final SolrDocumentList docs = rsp.getResults();
-            if (docs.isEmpty()) return null;
-            return docs.get(0);
-        } catch (final Throwable e) {
-            Log.logWarning("AbstractSolrConnection", "problem with id=" + id, e);
-            throw new IOException(e);
+        Throwable error = null; // well this is a bad hack; see https://issues.apache.org/jira/browse/LUCENE-2239
+        // also: https://issues.apache.org/jira/browse/SOLR-2247
+        // we might try also: $JAVA_OPTS -Dsolr.directoryFactory=solr.MMapDirectoryFactory
+        for (int retry = 30; retry > 0; retry--) {
+            try {
+                final QueryResponse rsp = this.server.query(query);
+                final SolrDocumentList docs = rsp.getResults();
+                if (docs.isEmpty()) return null;
+                if (error != null) Log.logWarning("AbstractSolrConnector", "produced search result by silently ignoring an error before, message = " + error.getMessage());
+                return docs.get(0);
+            } catch (final Throwable e) {
+                Log.logWarning("AbstractSolrConnection", "problem with id=" + id, e);
+                error = e;
+                continue;
+            }
         }
+        throw new IOException(error.getMessage(), error);
     }
 
 }

source/net/yacy/search/solr/EmbeddedSolrConnector.java

@@ -84,6 +84,13 @@ public class EmbeddedSolrConnector extends AbstractSolrConnector implements Solr
                 Files.copy(source, target);
             }
         }
+        /*
+        try {
+            CheckIndex.main(new String[]{new File(new File(storagePath, "data"), "index").getAbsolutePath(), "-fix"});
+        } catch (InterruptedException e1) {
+            Log.logException(e1);
+        }
+        */
         try {
             this.cores = new CoreContainer(storagePath.getAbsolutePath(), new File(solr_config, "solr.xml"));
         } catch (ParserConfigurationException e) {