Awkward Memory Issues

[Sid Singh]

Hi Folks,

I came across a strange problem while unit testing of my application accross various environments like first local server then pre-production server and so on.
I was getting below exception
java.io.IOException: Underlying input stream returned zero bytes

Tried lot many things but all failed. Then i realised that the data size that i was testing with was a bit large so i reduced the size and with the same code things went well.
On different server even with the large data set my code was running properly.
I wonder such exception in no way depicts about the actual problem.

Can someone throw some light on this?
Thanks
Siddharth

[Rob Spoor]

Can you show us the code that's throwing that exception, plus the stack trace?

[Sid Singh]

Rob Spoor wrote:Can you show us the code that's throwing that exception, plus the stack trace?

Hi Rob,
Thanks for replying

		String serverId = getClientSession(clientSessionId);

		Connection con = null;
		ResultSet rs = null;
		PreparedStatement ps = null;
		PacketData packetData = null;
		ArrayList<PacketData> packetDataList = null;


		DatabaseServices dataServices = null;
		try{
			if(logger.isDebugEnabled()) {
				logger.debug("Before Get connection");
			}
			dataServices = new DatabaseServices(appName);
			con= dataServices.getConnection();

			if(logger.isDebugEnabled()) {
				logger.debug("After Get connection");
			}
			ps = con.prepareStatement(QueryConstants.SELECT_PACKET_DATA);
			if(logger.isDebugEnabled()) {
				logger.debug("PS Executing the Query"+QueryConstants.SELECT_PACKET_DATA);
			}
			ps.setString(1,serverId);
			ps.setString(2, clientSessionId);
			ps.setString(3, type);
			rs = ps.executeQuery();
			if(logger.isDebugEnabled()) {
				logger.debug("PS Query Execution Complete");
			}
			if(rs != null){
				packetDataList = new ArrayList<PacketData>();
				while(rs.next()){
					Blob blob = rs.getBlob(QueryConstants.COL_DATA);
					java.io.InputStream in = blob.getBinaryStream();
					BufferedReader br = new BufferedReader(new InputStreamReader(in));
					StringBuilder sb = new StringBuilder();
					String line = null;
					[b]while ((line = br.readLine()) != null) {
						sb.append(line);
					}[/b]					
                                                                                String id = rs.getString(QueryConstants.COL_ID);
					String isRecieveCompleteStr = rs.getString(QueryConstants.COL_IS_REC_COMPLETE);
					packetData = new PacketData(serverId,clientSessionId, sb.toString(),id, type);
					if(isRecieveCompleteStr != null){
						if("Y".equals(isRecieveCompleteStr)){
							packetData.setRecieveComplete(Boolean.TRUE);
						}
						else{
							packetData.setRecieveComplete(Boolean.FALSE);
						}
					}
					packetDataList.add(packetData);
				}

			}
		}catch(Exception exception){
			logger.error("Error while Retrieving CDATA",exception);
			throw new CDataException(exception);

		}finally{
			try{
				if(ps != null)
					ps.close();
				if(rs != null)
					rs.close();
				if(con != null)
					con.close();
				if(dataServices != null)
					dataServices = null;
			}catch(Exception e){
				e.printStackTrace();
			}
		}

The lines marked bold always throw the IOException and then it gets propogated from there.
The Trace which i got was

java.io.IOException: Underlying input stream returned zero bytes
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:268)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:306)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158)
at java.io.InputStreamReader.read(InputStreamReader.java:167)
at java.io.BufferedReader.fill(BufferedReader.java:136)
at java.io.BufferedReader.readLine(BufferedReader.java:299)
at java.io.BufferedReader.readLine(BufferedReader.java:362)
at com.database.DatabaseServices.getPacketData(DatabaseServices.java:134)

Thanks
Siddharth Singh

[Rob Spoor]

You're trying to read text data from a BLOB. Perhaps that BLOB is not a properly encoded string, or it's not encoded with the default encoding. In the latter case you can specify the actual encoding in the InputStreamReader constructor. In the former case you can't convert the BLOB into a String at all.

Perhaps it's a better idea to start using a CLOB instead of a BLOB. BLOB is Binary Large OBject, meant for binary data. CLOB is Character Large OBject, meant for text. JDBC uses Reader and Writer for CLOB.