SOLR-6268: HdfsUpdateLog has a race condition that can expose a closed HDFS FileSystem instance and should close it's FileSystem instance if either inherited close method is called.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1619402 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -299,6 +299,9 @@ Bug Fixes
   
 * SOLR-6393: TransactionLog replay performance on HDFS is very poor. (Mark Miller)  
 
+* SOLR-6268: HdfsUpdateLog has a race condition that can expose a closed HDFS FileSystem instance and should 
+  close it's FileSystem instance if either inherited close method is called. (Mark Miller)
+
 Optimizations
 ---------------------
 

solr/core/src/java/org/apache/solr/update/HdfsTransactionLog.java

@@ -274,21 +274,12 @@ public class HdfsTransactionLog extends TransactionLog {
     try {
       synchronized (this) {
         fos.flushBuffer();
-        
-        // we must flush to hdfs
-        // TODO: we probably don't need to
-        // hsync below if we do this - I
-        // think they are equivalent.
-        tlogOutStream.hflush();
       }
 
       if (syncLevel == UpdateLog.SyncLevel.FSYNC) {
-        // Since fsync is outside of synchronized block, we can end up with a partial
-        // last record on power failure (which is OK, and does not represent an error...
-        // we just need to be aware of it when reading).
-        
-        //raf.getFD().sync();
         tlogOutStream.hsync();
+      } else {
+        tlogOutStream.hflush();
       }
 
     } catch (IOException e) {
@@ -304,20 +295,25 @@ public class HdfsTransactionLog extends TransactionLog {
       }
 
       synchronized (this) {
-        fos.flush();
+        fos.flushBuffer();
+      }
+      
       tlogOutStream.hflush();
-        fos.close();
-
       tlogOutStream.close();
-      }
 
+    } catch (IOException e) {
+      log.error("Exception closing tlog.", e);
+      throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, e);
+    } finally {
       if (deleteOnClose) {
+        try {
           fs.delete(tlogFile, true);
-      }
         } catch (IOException e) {
           throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, e);
         }
       }
+    }
+  }
 
   public String toString() {
     return "hdfs tlog{file=" + tlogFile.toString() + " refcount=" + refcount.get() + "}";

solr/core/src/java/org/apache/solr/update/HdfsUpdateLog.java

@@ -114,16 +114,18 @@ public class HdfsUpdateLog extends UpdateLog {
       }
     }
     
+    FileSystem oldFs = fs;
+    
     try {
-      if (fs != null) {
-        fs.close();
-      }
+      fs = FileSystem.newInstance(new Path(dataDir).toUri(), getConf());
     } catch (IOException e) {
       throw new SolrException(ErrorCode.SERVER_ERROR, e);
     }
     
     try {
-      fs = FileSystem.newInstance(new Path(dataDir).toUri(), getConf());
+      if (oldFs != null) {
+        oldFs.close();
+      }
     } catch (IOException e) {
       throw new SolrException(ErrorCode.SERVER_ERROR, e);
     }
@@ -278,8 +280,14 @@ public class HdfsUpdateLog extends UpdateLog {
   
   @Override
   public void close(boolean committed) {
-    synchronized (this) {
-      super.close(committed);
+    close(committed, false);
+  }
+  
+  @Override
+  public void close(boolean committed, boolean deleteOnClose) {
+    try {
+      super.close(committed, deleteOnClose);
+    } finally {
       IOUtils.closeQuietly(fs);
     }
   }