brouter/brouter-util/src/main/java/btools/util/StackSampler.java

package btools.util;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.Map;
import java.util.Random;

public class StackSampler extends Thread
{
  private DateFormat df = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss,SSS", new Locale( "en", "US" ) );
  private BufferedWriter bw;
  private Random rand = new Random();

  private int interval;
  private int flushCnt = 0;
  
  private volatile boolean stopped;

  public StackSampler( File logfile, int interval )
  {
    this.interval = interval;
    try
    {
      bw = new BufferedWriter( new OutputStreamWriter( new FileOutputStream( logfile, true ) ) );
    }
    catch (Exception e)
    {
      printError( "StackSampler: " + e.getMessage() );
    }
  }

  protected void printError( String msg )
  {
    System.out.println( msg );
  }

  @Override
  public void run()
  {
    while( !stopped )
    {
      dumpThreads();
    }
    if ( bw != null )
    {
      try
      {
        bw.close();
      }
      catch( Exception e ) {}
    }
  }

  public void dumpThreads()
  {
    try
    {
      int wait1 = rand.nextInt( interval );
      int wait2 = interval - wait1;
      Thread.sleep( wait1 );
      StringBuilder sb = new StringBuilder( df.format( new Date() ) + " THREADDUMP\n" );
      Map<Thread, StackTraceElement[]> allThreads = Thread.getAllStackTraces();
      for ( Map.Entry<Thread, StackTraceElement[]> e : allThreads.entrySet() )
      {
        Thread t = e.getKey();
        if ( t == Thread.currentThread() )
        {
          continue; // not me
        }

        StackTraceElement[] stack = e.getValue();
        if ( !matchesFilter( stack ) )
        {
          continue;
        }

        sb.append( " (ID=" ).append( t.getId() ).append( " \"" ).append( t.getName() ).append( "\" " ).append( t.getState() ).append( "\n" );
        for ( StackTraceElement line : stack )
        {
          sb.append( "    " ).append( line.toString() ).append( "\n" );
        }
        sb.append( "\n" );
      }
      bw.write( sb.toString() );
      if ( flushCnt++ >= 0 )
      {
        flushCnt = 0;
        bw.flush();
      }
      Thread.sleep( wait2 );
    }
    catch (Exception e)
    {
      // ignore
    }
  }

  public void close()
  {
    stopped = true;
    interrupt();
  }

  private boolean matchesFilter( StackTraceElement[] stack )
  {
    boolean positiveMatch = false;
    for ( StackTraceElement e : stack )
    {
      String s = e.toString();
      if ( s.indexOf( "btools" ) >= 0 )
      {
        positiveMatch = true;
      }
      if ( s.indexOf( "Thread.sleep" ) >= 0 )
      {
        return false;
      }
    }
    return positiveMatch;
  }

  public static void main( String[] args ) throws Exception
  {
    System.out.println( "StackSampler..." );
    Class<?> clazz = Class.forName( args[0] );
    String[] args2 = new String[args.length - 1];
    for ( int i = 1; i < args.length; i++ )
    {
      args2[i - 1] = args[i];
    }
    StackSampler t = new StackSampler( new File( "stacks.log" ), 1000 );
    t.start();
    try
    {
      clazz.getMethod( "main", String[].class ).invoke( null, new Object[]{ args2 } );
    }
    finally
    {
      t.close();
    }
  }
}