stop and garbage collect a network of threads
Hi,
i have written a p2p network simulator. Each peer is represented by a thread and owns a Mailbox (a Monitor). Threads/peers own references to mailboxes of other threads/peers -and places data there- and their mailboxes are "pointed to" by other threads/peers. A peer/thread is blocking/waiting if its Mailbox is empty. A peer/thread may also be in a sleep state.
The run method of the Peer (implements Runnable) class:
publicvoid run()
{
while (executable_)
{
cat_.info(thisPeerId_+" processing messages ...");
Iterator<MsgInterface> iter=getMessages().iterator();
while (iter.hasNext())
{
MsgInterface msg=iter.next();
processMessage((Msg)msg);
}
try
{
Thread.sleep(DELAY);
}
catch (InterruptedException e)
{
thisMailbox_=null;
thePit_=null;
return;
}
}
}//run
(1) How can i kill all this threads? One method i have used is calling the "setExecutable(boolean flag)" on each peer and changing the flag of the outer while loop of the run() method. This doesn't work since most threads block most of the time and they do not revalidate the while condition.
(2) Another method i have used is calling the interrupt method on each thread/Peer, in order the
thisMailbox_=null;
thePit_=null;
return;
to be executed. However, since it is waiting and not sleeping most of the time, this doesn't work either.
(3) I will probably have to do something with the Monitors and the "waiting" state of the threads.
Can somebody please provide advice? I probably need a combination to handle all (1),(2),(3) above -isn't it?
Another question; in the general case, one does a setExecutable(false) on a thread -and a thread validates the condition and stops running, would the thread get garbage collected?
Thanks a lot!
[2665 byte] By [
uiga] at [2007-11-27 4:24:48]
# 2
Here's the Mailbox code:
package swarm.sys.mail;
import java.util.*;
import java.io.*;
import org.apache.log4j.*;
import swarm.sys.id.*;
import swarm.sys.interfaces.*;
import swarm.sys.common.*;
import swarm.sys.peers.messages.*;
import swarm.sys.farm.*;
import swarm.sys.peers.*;
public abstract class Mailbox implements Serializable
{
/************************************CONSTRUCTOR_FIELDS***************************************/
protected IDInterface id_;
protected String label_;
/************************************CONSTRUCTOR_FIELDS***************************************/
protected boolean empty_=true;
protected Vector<MsgInterface> msgBox_=new Vector<MsgInterface>();
/* to be used by the Peers
*/
protected Mailbox(IDInterface id)
{
label_="no-label";
id_=id;
}//Mailbox
/* to be used by the monitor and the farms;
* label can be: FIN_MAIL, FOUT_MAIL, FPIT_MAIL, MIN_MAIL, SMIN_MAIL
*/
protected Mailbox(String label)
{
id_=new ID("UNSPECIFIED",0);
label_=label;
}//Mailbox
/* label cannot change after Mailbox creation, so method
* doesn't need to be synchronized
*/
public String getLabel()
{
return label_;
}//getLabel
/* id cannot change after Mailbox creation, so method
* doesn't need to be synchronized
*/
public IDInterface getId()
{
return id_;
}//getId
public synchronized boolean isEmpty()
{
return empty_;
}//isEmpty
public abstract Collection<MsgInterface> removeAndGetMessages();
public abstract void addMessage(MsgInterface msg);
public synchronized Collection<MsgInterface> messageSnapshot()
{
Collection<MsgInterface> msgBoxCopy=new HashSet<MsgInterface>();
msgBoxCopy.addAll(msgBox_);
return msgBoxCopy;
}//messageSnapshot
public synchronized String toString()
{
String s="";
s=s+'\n';
s=s+"--"+'\n';
s=s+" Mailbox: "+label_.toString()+'\n';
s=s+"--"+'\n';
if (empty_)
{
s=s+"empty"+'\n';
}
else
{
for (MsgInterface msg: msgBox_)
{
if (msg.getMsgId()!=null)
s=s+msg.toString()+'\n';
else
s=s+msg.getMsgId().toString()+'\n';
}
}
return s;
}//toString
public static Mailbox newMailbox(Object o)
{
if (o instanceof IDInterface)
{
return new PeerMailbox((IDInterface)o);
}//instanceof PeerBasic
else
if (o instanceof String)
{
String type=(String)o;
if (type.equals("FIN_MAIL"))
{
return new FarmInMailbox();
}//FarmInMailbox
else if (type.equals("FOUT_MAIL"))
{
return new FarmOutMailbox();
}//FarmOutMailbox
else if (type.equals("FPIT_MAIL"))
{
return new FarmPitMailbox();
}//FarmPitMailbox
else if (type.equals("MPIT_MAIL"))
{
return new MonitorPitMailbox();
}//MonitorPitMailbox
else if (type.equals("MIN_MAIL"))
{
return new MonitorInMailbox();
}//MonitorInMailbox
else if (type.equals("MOUT_MAIL"))
{
return new MonitorOutMailbox();
}//MonitorOutMailbox
else if (type.equals("MSIN_MAIL"))
{
return new MonitorSInMailbox();
}//MonitorSInMailbox
else if (type.equals("MSOUT_MAIL"))
{
return new MonitorSOutMailbox();
}//MonitorSInMailbox
else if (type.equals("FSOUT_MAIL"))
{
return new FarmSOutMailbox();
}//FarmSOutMailbox
else if (type.equals("FSIN_MAIL"))
{
return new FarmSInMailbox();
}//FarmSInMailbox
}//instanceof String
return null;
}//newMailbox
}
and here's the PeerMailbox code -there are other kind of mailboxes too:
package swarm.sys.mail;
import org.apache.log4j.*;
import java.util.*;
import java.net.*;
import swarm.sys.farm.*;
import swarm.sys.interfaces.*;
import swarm.sys.common.*;
public class PeerMailbox extends Mailbox
{
private static transient Logger cat_=Farm.getLogger();
private String hostname_;
public PeerMailbox(IDInterface id)
{
super(id);
try
{
hostname_= Net.extractHostname(InetAddress.getLocalHost());
}
catch (UnknownHostException ex)
{
ex.printStackTrace();
}
}//PeerMail
public synchronized Vector<MsgInterface> removeAndGetMessages()
{
while (empty_)
{
try
{
wait();
}
catch(InterruptedException e)
{
}
}
Vector<MsgInterface> msgBoxCopy=new Vector<MsgInterface>();
msgBoxCopy.addAll(msgBox_);
//logging
String nsMsgId="";
if (!(cat_.getLevel().equals(Level.OFF)))
{
Iterator<MsgInterface> iMsgBox=msgBox_.iterator();
while (iMsgBox.hasNext())
{
IDInterface anId=iMsgBox.next().getMsgId();
nsMsgId=nsMsgId+ anId.toString()+" ";
}
}
cat_.info(id_+" PeerMail: removing all messages with identifiers: "+nsMsgId);
//logging
msgBox_.clear();
empty_=true;
notifyAll();
return msgBoxCopy;
}//removeAndGetMessages
public synchronized void addMessage(MsgInterface msg)
{
msgBox_.add(msg);
cat_.info(id_+" PeerMail: added message "+ msg.getMsgId());
empty_=false;
notifyAll();
}//addMessage
public synchronized String toString()
{
String s="";
s=s+'\n';
s=s+"--"+'\n';
s=s+" Mailbox: "+id_.toString()+'\n';
s=s+"--"+'\n';
if (empty_)
{
s=s+"empty"+'\n';
}
else
{
Iterator<MsgInterface> iter=msgBox_.iterator();
while (iter.hasNext())
{
s=s+iter.next().getMsgId().toString()+'\n';
}
}
return s;
}//toString
}
uiga at 2007-7-12 9:32:44 >
