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From Øystein Grøvlen (JIRA) <j...@apache.org>
Subject [jira] Commented: (DERBY-3243) (jdbc net client) exception during normal iteration through "ResultSet" of "select * from t"
Date Wed, 30 Jan 2008 14:32:34 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3243?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12564031#action_12564031
] 

Øystein Grøvlen commented on DERBY-3243:
----------------------------------------

I think part of the confusion here is that EmbedConnection#lobHashMap
is used for two separate purposes.  It was first added as a mechanism
for the NetworkServer to add locators mapping for locators that were
sent to the client.  This mechanism was intented to by driven by the
NetworkServer, but EmbedConnection is used for storage since it is
persistent across client requests.

Later, the same hash map was used to store references to all internal
Lobs in order to be able to do clean-up at end of transaction.  (I was
wrong when I earlier wrote that this was really only needed for LOB
objects that had associated temporary files.  This mechanism is used
in order to invalidate any active LOB object at the end of
transaction.)

There are other ways to achieve invalidation at end of transaction,
but as long as we are using the current mechanism, it will be
necessary to keep track of all active LOB objects of a connection.
Given that, it is not necessary for the network server to do its own
book-keeping.  Instead, it could rely on the embedded driver for this.
I think Kathey's patch is a step in the right direction here, but as
Knut Anders suggest I think we should go a step further and remove all
traces of how this is currently done by the network server.

I also think that it would be better if this clean-up was tied to
DERBY-3354 which I feel is more related.  Then this JIRA could focus
on the DRDA problems that causes the reported bug. (I will discuss
that issue in a separate comment.)


> (jdbc net client) exception during normal iteration through "ResultSet" of "select *
from t"
> --------------------------------------------------------------------------------------------
>
>                 Key: DERBY-3243
>                 URL: https://issues.apache.org/jira/browse/DERBY-3243
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>    Affects Versions: 10.3.2.1
>         Environment: ------------------ Java Information ------------------
> Java Version:    1.4.2_03
> Java Vendor:     Sun Microsystems Inc.
> Java home:       C:\Programme\Java\j2re1.4.2_03
> Java classpath:  derbyclient.jar
> OS name:         Windows XP
> OS architecture: x86
> OS version:      5.1
> Java user name:  cbdqok
> Java user home:  C:\Dokumente und Einstellungen\cbdqok
> Java user dir:   D:\users\cbdqok\privat\osj\lib_derby_net\lib
> java.specification.name: Java Platform API Specification
> java.specification.version: 1.4
> --------- Derby Information --------
> JRE - JDBC: J2SE 1.4.2 - JDBC 3.0
> [D:\users\cbdqok\privat\osj\lib_derby_net\lib\derbyclient.jar] 10.3.1.4 - (561794)
> ------------------------------------------------------
> ----------------- Locale Information -----------------
> ------------------------------------------------------
>            Reporter: Oliver Seidel
>            Priority: Critical
>         Attachments: derby-3243_fix_double_hashmap_entry_diff.txt, derby-3243_fix_double_hashmap_entry_diff2.txt,
derby-3243_fix_double_hashmap_entry_stat.txt
>
>
> Thanks again to the DERBY developers.
> For my convenience I use the client/server variant of DERBY.  This is where the error
occurs.  I have temporarily alleviated the problem for my case by using the embedded version.
> I'm forced to use outlook and have built a program which siphons the messages into a
derby database (phase 1 -- table has two varchar fields and a clob).  When reading them back
(phase 2 -- simple select of all records in no particular order, all 3 attributes), it has
developed an exception.  This is a result of data volume.  I have reduced the problem to a
single demonstration program.
> This behaviour, and the fact that the error is not a "DERBY Exception", but a proper
exception coming back from the JDBC call, leads me to the diagnosis that it is a derby network
client jdbc problem.
> The problem has been reproduced once by Bryan Pendleton: http://www.nabble.com/IndexOutOfBoundsException-t4926228.html
> I'll try to attach the code "error.java"; it can also be found on: http://www.os10000.net/error.java
> Please use as follows:
> javac -classpath derby.jar:derbynet.jar error.java
> java -cp .:derby.jar:derbynet.jar error
> It will create a directory "test_db" and fill it with approx 120mb data.
> Then you will observe the failure. 
> /* -*- Mode:Java; c-basic-offset:8 -*- */
> // --------------------------------------------------------------------------------
> public class error {
> 	// ------------------------------------------------------------------------
> 	public static final int port = 1527;
> 	public static final String host = "127.0.0.1";
> 	// ------------------------------------------------------------------------
> 	public static void log(String x) { System.out.println(x); };
> 	// ------------------------------------------------------------------------
> 	public static void log_stacktrace(Exception e) {
>                 java.io.StringWriter sw = new java.io.StringWriter();
>                 java.io.PrintWriter pw = new java.io.PrintWriter(sw);
>                 e.printStackTrace(pw);
>                 log(sw.toString());
> 	};
> 	// ------------------------------------------------------------------------
> 	public static void start_server() {
> 		try {
> 			org.apache.derby.drda.NetworkServerControl server =
> 				new org.apache.derby.drda.NetworkServerControl(java.net.InetAddress.getByName(host),port);
> 			server.start(null);
> 			try { java.lang.Thread.sleep(5000); } catch (Exception e) { };
> 			log("started DERBY on host "+host+" port "+Integer.toString(port)+".");
> 		} catch (Exception e) {
> 			log_stacktrace(e);
> 		};
> 	};
> 	// ------------------------------------------------------------------------
> 	public static java.sql.Connection con()
> 		throws java.sql.SQLException, java.lang.ClassNotFoundException {
> 		Class.forName("org.apache.derby.jdbc.ClientDriver");
> 		String x_dbse = "test_db";
> 		String x_user = ";user=os10000";
> 		String x_pass = ";password=ding";
> 		String x_crte = ";create=true";
> 		String x_msgs = ";retrieveMessagesFromServerOnGetMessage=true";
> 		String connect = "jdbc:derby://"+host+":"+port+"/"+x_dbse+x_user+x_crte+x_msgs;
> 		return java.sql.DriverManager.getConnection(connect);
> 	};
> 	// ----------------------------------------------------------------------
> 	public static String getclob(java.sql.Clob b) {
> 		java.io.CharArrayWriter caw = new java.io.CharArrayWriter();
> 		try {
> 			java.io.Reader rd = b.getCharacterStream();
> 			char cb[] = new char[4096];
> 			int off=0, bts = rd.read(cb);
> 			while (bts>0) { caw.write(cb,off,bts); off+=bts; bts=rd.read(cb); };
> 			rd.close();
> 		} catch(Exception e) {};
> 		String res = caw.toString();
> 		caw.close();
> 		return res;
> 	};
> 	// ----------------------------------------------------------------------
> 	public static class myclob implements java.sql.Clob {
> 		String v;
> 		public myclob(String z) { v=z; };
> 		public java.io.InputStream getAsciiStream() { return new java.io.ByteArrayInputStream(v.getBytes());
};
> 		public java.io.Reader getCharacterStream() { return new java.io.CharArrayReader(v.toCharArray());
};
> 		public String getSubString(long pos, int length) { return v.substring((int)pos,(int)(pos+length));
};
> 		public long length() { return v.length(); };
> 		public long position(java.sql.Clob pattern, long start) { return 0; };
> 	        public long position(String pattern, long start) { return 0; };
> 		public java.io.OutputStream setAsciiStream(long pos) {
> 			new java.sql.SQLException("setAsciiStream not implemented."); return null; };
> 		public java.io.Writer setCharacterStream(long pos) {
> 			new java.sql.SQLException("setCharacterStream not implemented."); return null; };
> 		public int setString(long pos, String s) {
> 			new java.sql.SQLException("setString not implemented."); return -1; };
> 		public int setString(long pos, String s, int offset, int len) {
> 			new java.sql.SQLException("setString not implemented."); return -1; };
> 		public void truncate(long len) {
> 			new java.sql.SQLException("truncate not implemented."); };
> 	};
> 	public static java.sql.Clob putclob(String x) { return new myclob(x); };
> 	
> 	// ------------------------------------------------------------------------
> 	public static String getLob(java.sql.ResultSet rs, int arg)
> 		throws java.sql.SQLException { return getclob(rs.getClob(arg)); };
> 	public static void setLob(java.sql.PreparedStatement ps, int arg, String val)
> 		throws java.sql.SQLException { ps.setClob(arg,putclob(val)); };
> 	// ------------------------------------------------------------------------
> 	public static String clean_string(String x) {
> 		return x.replaceAll("[\0\r\\\\]","").replaceAll("'","\\\"").replaceAll(",+",",");
> 	};
> 	// ------------------------------------------------------------------------
> 	public static String make_string(int digits) {
> 		double dl = (Math.random()) * (Math.pow(10.0,digits*Math.random()));
> 		int len = (int) dl;
> 		byte buf[] = new byte[len];
> 		while (len>0) {
> 			double db = 256*Math.random();
> 			buf[--len] = (byte)db;
> 		};
> 		return clean_string(new String(buf));
> 	};
> 	// ------------------------------------------------------------------------
> 	public static void update(java.sql.Connection c, String cmd)
> 		throws java.sql.SQLException {
> 		c.createStatement().execute(cmd);
> 	};
> 	// ------------------------------------------------------------------------
> 	public static final int entries=100000;
> 	public static void fill_db(java.sql.Connection c)
> 		throws java.sql.SQLException {
> 		try { update(c,"drop table mail_raw"); } catch (Exception e) {};
> 		try { update(c,"create table mail_raw ( msg varchar(999), att varchar(100), val clob
)"); } 
> 		catch (Exception e) { log_stacktrace(e); };
> 		java.sql.PreparedStatement pstmt = null;
> 		try { pstmt = c.prepareStatement("insert into mail_raw values ( ?, ?, ? )"); }
> 		catch (Exception e) { log_stacktrace(e); };
> 		for (int i=0; i<entries; i++) {
> 			pstmt.setString(1,make_string(3));
> 			pstmt.setString(2,"5 body");
> 			setLob(pstmt,3,make_string(4));
> 			pstmt.executeUpdate();
> 			if (i%100==0) log("step "+i+"/"+entries);
> 		};
> 	};
> 	// ------------------------------------------------------------------------
> 	public static void dump_db(java.sql.Connection c)
> 		throws java.sql.SQLException {
> 		log("performing dump.");
> 		java.sql.ResultSet rs = c.createStatement().executeQuery("select * from mail_raw");
> 		while (rs.next()) {
> 			String msg = rs.getString(1);
> 			String att = rs.getString(2);
> 			String val = getLob(rs,3);
> 		};
> 	};
> 	// ------------------------------------------------------------------------
> 	public static void main(String args[]) {
> 		start_server();
> 		try {
> 			java.sql.Connection c = con();
> 			fill_db(c);
> 			dump_db(c);
> 		} catch (Exception e) { log_stacktrace(e); };
> 	};
> 	// ------------------------------------------------------------------------
> };

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