What are the different ways to handle deadlocks?

Question

Hi,
May I know what are the ways to solve a deadlock problem?
Currently, I have the following code to catch the exception:
catch (XmlException ex)
               try
                    ex.printStackTrace();
                    txn.abort();
               } catch (DatabaseException DbEx)
                    System.err.println("txn abort failed.");
               }and the resulting error is:
com.sleepycat.dbxml.XmlException: Error: DB_LOCK_DEADLOCK: Locker killed to resolve a deadlock, errcode = DATABASE_ERROR
Any other more efficient way to handle deadlock?
Or better ways to prevent deadlock from happening?
I am using this environment config
EnvironmentConfig envConf = new EnvironmentConfig();
               envConf.setAllowCreate(true); // If the environment does not exits,
               // create it.
               envConf.setInitializeCache(true); // Turn on the shared memory
               // region.
               // envConf.setCacheSize(25 * 1024 * 1024); // 25MB cache
               envConf.setInitializeLocking(true); // Turn on the locking
               // subsystem.
               envConf.setInitializeLogging(true); // Turn on the logging
               // subsystem.
               envConf.setTransactional(true); // Turn on the transactional
               // subsystem.
               // envConf.setRunRecovery(true); //Turn on run recovery
               // envConf.setTxnNoSync(true); // Cause BDB XML to not synchronously
               // force any log data to disk upon transaction commit
               envConf.setLogInMemory(true); // specify in-memory logging
               envConf.setLogBufferSize(60 * 1024 * 1024); // set logging size.
               // envConf.setTxnWriteNoSync(true); //method. This causes logging
               // data to be synchronously written to the OS's file system buffers
               // upon transaction commit.
               // envConf.setThreaded(true); //default by Java that threaded = true
               // envConf.setMultiversion(true);
               envConf.setLockDetectMode(LockDetectMode.DEFAULT); // Reject a
               // random lock
               // requestThanks in advance for any help!
:)

Answer 1

Hi Vyacheslav,
here is the code:
package ag;
import com.sleepycat.db.DatabaseException;
import com.sleepycat.db.Environment;
import com.sleepycat.db.EnvironmentConfig;
import com.sleepycat.db.LockDetectMode;
import com.sleepycat.dbxml.XmlContainerConfig;
import com.sleepycat.dbxml.XmlDocumentConfig;
import com.sleepycat.dbxml.XmlException;
import com.sleepycat.dbxml.XmlManager;
import com.sleepycat.dbxml.XmlContainer;
import com.sleepycat.dbxml.XmlDocument;
import com.sleepycat.dbxml.XmlManagerConfig;
import com.sleepycat.dbxml.XmlTransaction;
import com.sleepycat.dbxml.XmlUpdateContext;
import inter.DBInterface;
import java.io.*;
import java.util.Properties;
import cp.CheckPointer;
public class SaveMessageinDB implements DBInterface
     Environment myEnv;
     XmlManager myManager;
     XmlContainer myContainer;
     XmlTransaction txn;
     XmlContainerConfig cconfig;
     Properties properties;
     // CheckPointer cp;
     int Counter;
     public SaveMessageinDB()
          try
               properties = new Properties();
               properties.load(ClassLoader
                         .getSystemResourceAsStream("Aggregator.properties"));
               setXmlEnvrionment();
               setXmlManager();
               setXmlContainer();
               // cp = new CheckPointer(myEnv);
               // cp.start();
               // System.out.println("Checkpointer started....");
               Counter = 0;
          } catch (Exception ex)
               ex.printStackTrace();
     public void saveMessage(String docName, String content) throws Exception
          addXMLDocument(docName, content);
     public void setXmlEnvrionment()
          try
               File envHome = new File(properties.getProperty("DATABASE_LOCATION"));
               EnvironmentConfig envConf = new EnvironmentConfig();
               envConf.setAllowCreate(true); // If the environment does not exits,
               // create it.
               envConf.setInitializeCache(true); // Turn on the shared memory
               // region.
               envConf.setCacheSize(100 * 1024 * 1024); // 100MB cache
               envConf.setInitializeLocking(true); // Turn on the locking
               // subsystem.
               envConf.setInitializeLogging(true); // Turn on the logging
               // subsystem.
               envConf.setTransactional(true); // Turn on the transactional
               // subsystem.
               // envConf.setRunRecovery(true); // Turn on run recovery
               // envConf.setTxnNoSync(true); // Cause BDB XML to not synchronously
               // force any log data to disk upon transaction commit
               envConf.setLogInMemory(true); // specify in-memory logging
               envConf.setLogBufferSize(60 * 1024 * 1024); // set logging size.
               // envConf.setTxnWriteNoSync(true);
               // This causes logging
               // data to be synchronously written to the OS's file system buffers
               // upon transaction commit.
               envConf.setMultiversion(true); //Turn on snapshot isolation
               envConf.setLockDetectMode(LockDetectMode.DEFAULT); // Reject a
               // random lock
               // request
               // myEnv = new Environment(envHome, null); //To adopt Environment
               // already set by others
               myEnv = new Environment(envHome, envConf);
               System.out.println("Environment created...");
          } catch (Exception ex)
               ex.printStackTrace();
     // All BDB XML programs require an XmlManager instance.
     // Create it from the DB Environment, but do not adopt the
     // Environment
     public void setXmlManager()
          try
               XmlManagerConfig mconfig = new XmlManagerConfig();
               mconfig.setAllowAutoOpen(true);
               mconfig.setAdoptEnvironment(true);
               mconfig.setAllowExternalAccess(true);
               myManager = new XmlManager(myEnv, mconfig);
               // myManager = new XmlManager (mconfig);
               System.out.println("Manager created...");
          } catch (Exception ex)
               ex.printStackTrace();
     public void setXmlContainer()
          try
               cconfig = new XmlContainerConfig();
               cconfig.setNodeContainer(true);
               cconfig.setIndexNodes(true);
               cconfig.setTransactional(true); // set transaction need an
               // cconfig.setAllowValidation(false);
               // environment
               // cconfig.setReadUncommitted(true); // This container allow
               // uncommitted read (able to read dirty data and not set a deadlock
               // cconfig.setMultiversion(true);
               myContainer = myManager.openContainer(properties
                         .getProperty("DATABASE_LOCATION")
                         + properties.getProperty("CONTAINER_NAME"), cconfig);
               System.out.println("Container Opened...");
          } catch (XmlException XmlE)
               try
                    myContainer = myManager.createContainer(properties
                              .getProperty("DATABASE_LOCATION")
                              + properties.getProperty("CONTAINER_NAME"), cconfig);
                    System.out.println("Container Created...");
               } catch (Exception e)
                    e.printStackTrace();
          } catch (Exception ex)
               ex.printStackTrace();
     public void addXMLDocument(String docName, String content)
          try
               txn = myManager.createTransaction(); // no need to create
               // transaction. auto commit
               // by the environment
               XmlDocumentConfig docConfig = new XmlDocumentConfig();
               docConfig.setGenerateName(true);
               docConfig.setWellFormedOnly(true);
               myContainer.putDocument(txn, docName, content, docConfig);
               // commit the Transaction
               txn.commit();
               System.out.println("documents added.....");
               Counter++;
               System.out.println("Document no: " + Counter);
               txn.delete();
          } catch (XmlException ex)
               try
                    System.out.println("Occuring in addXMLDocument");
                    ex.printStackTrace();
                    txn.abort();
               } catch (DatabaseException DbEx)
                    System.err.println("txn abort failed.");
     public void cleanup()
          try
               if (myContainer != null)
                    myContainer.close();
               if (myManager != null)
                    myManager.close();
               if (myEnv != null)
                    System.out.println("All cleaned up done..in sm");
                    myEnv.close();
          } catch (Exception e)
               // ignore exceptions in cleanup
}Thanks!