Please Daren advice , multi-threaded concurrent reads

  package tt;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  public class ParaTest {
  	/**
  	 * @param args
  	 */
  	public static void main(String[] args) throws Exception {
  
      /**
       *  目的: 比较两种方法的速率快慢
       *  第一种方法: 单独一个线程串行的向日志文件中写入2048个元素
       *  第二种方法: 两个线程并行，一个线程生成2048个元素后，另外一个获取该容器的锁，并写入日志文件。
       *  	 	 
       */
  
  		/**
  		 * case 1:
  		 */
  		PThread_1 p1 = new PThread_1();
  		Thread t1 = new Thread(p1);
  		long startTime = System.currentTimeMillis();
  		t1.start();
  		t1.join();
  		long endTime = System.currentTimeMillis();
  		System.out.println("The T1 running time is :" + (endTime - startTime));
  
  		/**
  		 * case 2:
  		 */
  		PThread_2 p2 = new PThread_2();
  		PThread_3 p3 = new PThread_3();
  		Thread t2 = new Thread(p2);
  		Thread t3 = new Thread(p3);
  		t2.start();
  		t2.join();
  		
  		startTime = System.currentTimeMillis();
   		t3.start();
   		t3.join();
  		endTime = System.currentTimeMillis();
  		System.out.println("The T3 running time is :"
  				+ (endTime - startTime));
  	}
  
  }
  
  class PThread_1 implements Runnable {
  
  	public static List<Long> lt = new ArrayList<Long>();
  	public static final Log pThread_1 = LogFactory.getLog(PThread_1.class);
  
  	PThread_1() {
  	}
  
  	@Override
  	public void run() {
  		// TODO Auto-generated method stub
  		while (lt.size() < 2048) {
  			lt.add(System.currentTimeMillis());
  		}
  
  		for (int i = 0; i < 2048 ; i++) {
  			pThread_1.info(lt.get(i));
  		}
  		 
  		lt.clear();
  	}
  }
  
  class PThread_2 implements Runnable {
  
  	public static List<Long> lt = new ArrayList<Long>();
  
  	PThread_2() {
  	}
  
  	@Override
  	public void run() {
  		synchronized (lt) {
  			while (lt.size() < 2048) {
  				lt.add(System.currentTimeMillis());
  			}
  //			lt.notifyAll();
  		}
  	}
  }
  
  class PThread_3 implements Runnable {
  
  	public static final Log pThread_3 = LogFactory.getLog(PThread_3.class);
  
  	PThread_3() {
  	}
  
  	@Override
  	public void run() {
  		// TODO Auto-generated method stub
  		synchronized (PThread_2.lt) {
  //				try {
  //					if(PThread_2.lt.size()<2048)
  //					PThread_2.lt.wait();
  //				} catch (InterruptedException e) {
  //					// TODO Auto-generated catch block
  //					e.printStackTrace();
  //				}
  			
  			while (PThread_2.lt.size() >= 2048) {
  				for (int i = 0; i < PThread_2.lt.size(); i++)
  					pThread_3.info(PThread_2.lt.get(i));
  			}
  			PThread_2.lt.clear();
  		}
  	}
  }
  

log4j configuration file is as follows:

  log4j.rootLogger=WARN
  
  log4j.logger.pThread_1=INFO,p1
  log4j.appender.p1=org.apache.log4j.FileAppender
  log4j.appender.p1.File=D://log4j/pThread_1.log 
  log4j.appender.p1.layout=org.apache.log4j.PatternLayout
  log4j.appender.p1.layout.ConversionPattern=%d %p [%c] - %m%n
  
  log4j.logger.pThread_3=INFO,p3
  log4j.appender.p3=org.apache.log4j.FileAppender
  log4j.appender.p3.File=D://log4j/pThread_3.log 
  log4j.appender.p3.layout=org.apache.log4j.PatternLayout
  log4j.appender.p3.layout.ConversionPattern=%d %p [%c] - %m%n
  

two problems :
1. t3 thread behind the delay in the end .
2. two are not the contents of the log file output .
I do not know what the reasons are . Great God seeking guidance.
------ Solution ---------------------------------------- ----
PThread_3 a while did not enter it, you PThread_2 a while the cycle is dead , right ? lt.size () == 0
------ Solution ---------------------------- ----------------
roof . . .
------ Solution ---------------------------------------- ----

  
PThread_3 synchronization part wrong, change if enough   
if (PThread_2.lt.size ()> = 2048) {   
for (int i = 0; i pThread_3.info (PThread_2.lt.get (i));   
}   
  
just log or not the content written into ...  

Oh, right right.
log your side is LogFactory.getLog (PThread_3.class) obtained , PThread_3.class is the complete package path , then your configuration file should log4j.logger. package path
------ For reference only ---------------------------------------


loop every time plus one , ah !
while (lt.size () <2048) {
lt.add (System.currentTimeMillis ());
}

------ For reference only ---------------------------------- -----


PThread_3 synchronization part wrong, change if enough
if (PThread_2.lt.size ()> = 2048) {
for (int i = 0; i pThread_3.info (PThread_2.lt.get (i));
}

just log or not the content written into ...
------ For reference only ------------------------ ---------------
I remember how log4j itself on multiple threads to synchronize concurrent writes a
------ For reference only ---- -----------------------------------

    
PThread_3 synchronization part wrong, change if enough     
if (PThread_2.lt.size ()> = 2048) {     
for (int i = 0; i pThread_3.info (PThread_2.lt.get (i));     
}     
    
just log or not the content written into ...          
  
Oh, right right.   
log your side is LogFactory.getLog (PThread_3.class) obtained , PThread_3.class is the complete package path , then your configuration file should log4j.logger. package path  
Yes