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POCan this loop take out 100% CPU?
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2010-05-15T11:22:43.313
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I created a chat application and seems to work just fine except that it takes up 100% cpu. Can this loop take out 100% Cpu? If yes, then what do i do to overcome it? <pre><code> @Override public void run(){ try { _objServerSocket = new ServerSocket(17001, 500); while (true) { try { initializeConnection(); addNewChatClient(); Thread.sleep(1000); } catch (Exception ex) { } } } catch (IOException ex) { System.out.println(ex.getCause() + "\n"+ ex.getMessage() + "\n" + ex.getStackTrace()); } } </code></pre> Thanks in advance :) Hi Bozho, Phil and Starkey. This is the exception that i get. <pre><code>SEVERE: java.util.ConcurrentModificationException at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372) at java.util.AbstractList$Itr.next(AbstractList.java:343) at misc.ChatRoom.cleanUpStreams(ChatRoom.java:34) at misc.ChatServer.cleanUpStreams(ChatServer.java:85) at common.Global.cleanupTasks(Global.java:81) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.sun.ejb.containers.interceptors.BeanCallbackInterceptor.intercept(InterceptorManager.java:1006) at com.sun.ejb.containers.interceptors.CallbackChainImpl.invokeNext(CallbackChainImpl.java:61) at com.sun.ejb.containers.interceptors.CallbackInvocationContext.proceed(CallbackInvocationContext.java:109) at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doCallback(SystemInterceptorProxy.java:133) at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.destroy(SystemInterceptorProxy.java:120) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.sun.ejb.containers.interceptors.CallbackInterceptor.intercept(InterceptorManager.java:961) at com.sun.ejb.containers.interceptors.CallbackChainImpl.invokeNext(CallbackChainImpl.java:61) at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:390) at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:373) at com.sun.ejb.containers.AbstractSingletonContainer$SingletonContextFactory.destroy(AbstractSingletonContainer.java:727) at com.sun.ejb.containers.AbstractSingletonContainer.doConcreteContainerShutdown(AbstractSingletonContainer.java:638) at com.sun.ejb.containers.BaseContainer.onShutdown(BaseContainer.java:4111) at org.glassfish.ejb.startup.SingletonLifeCycleManager.doShutdown(SingletonLifeCycleManager.java:166) at org.glassfish.ejb.startup.EjbApplication.stop(EjbApplication.java:240) at org.glassfish.internal.data.EngineRef.stop(EngineRef.java:165) at org.glassfish.internal.data.ModuleInfo.stop(ModuleInfo.java:268) at org.glassfish.internal.data.ApplicationInfo.stop(ApplicationInfo.java:251) at com.sun.enterprise.v3.server.ApplicationLifecycle.unload(ApplicationLifecycle.java:759) at com.sun.enterprise.v3.server.ApplicationLifecycle.undeploy(ApplicationLifecycle.java:790) at org.glassfish.deployment.admin.UndeployCommand.execute(UndeployCommand.java:184) at com.sun.enterprise.v3.admin.CommandRunnerImpl$1.execute(CommandRunnerImpl.java:305) at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:320) at com.sun.enterprise.v3.admin.CommandRunnerImpl.doCommand(CommandRunnerImpl.java:1176) at com.sun.enterprise.v3.admin.CommandRunnerImpl.access$900(CommandRunnerImpl.java:83) at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1235) at com.sun.enterprise.v3.admin.CommandRunnerImpl$ExecutionContext.execute(CommandRunnerImpl.java:1224) at com.sun.enterprise.v3.admin.AdminAdapter.doCommand(AdminAdapter.java:365) at com.sun.enterprise.v3.admin.AdminAdapter.service(AdminAdapter.java:204) at com.sun.grizzly.tcp.http11.GrizzlyAdapter.service(GrizzlyAdapter.java:166) at com.sun.enterprise.v3.server.HK2Dispatcher.dispath(HK2Dispatcher.java:100) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:245) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:619) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) SEVERE: java.net.SocketException: Socket closed at java.net.SocketInputStream.socketRead0(Native Method) at java.net.SocketInputStream.read(SocketInputStream.java:129) at java.net.SocketInputStream.read(SocketInputStream.java:182) at java.io.ObjectInputStream$PeekInputStream.peek(ObjectInputStream.java:2249) at java.io.ObjectInputStream$BlockDataInputStream.peek(ObjectInputStream.java:2542) at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2552) at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1297) at java.io.ObjectInputStream.readObject(ObjectInputStream.java:351) at misc.ChatClient.run(ChatClient.java:71) </code></pre> And this exception continues endlessly as it is in loop. I would like to add that everything works fine. But this starts if some client is connected to serversocket and i again redeploy my application :d. I know you woulnt't want to do that, but still how should i avoid it? Should i remove the inner try catch? so that once any error comes it is directly thrown out of loop? But this doesn't seem practical. Does it? Since one client may face some problem connecting to the serversocket, does not mean that i should terminate my application only. Now can you all help me? This is my whole ChatRoom class :- <pre><code>package misc; import java.io.IOException; import java.util.ArrayList; public class ChatRoom { private ArrayList<ChatClient> _objChatMembers; private int roomId = 0; public ChatRoom(int roomId){ this.roomId = roomId; this._objChatMembers = new ArrayList<ChatClient>(); System.out.println("Chat ROom created :" + roomId); } public ArrayList<ChatClient> getObjChatMembers() { return _objChatMembers; } public int getRoomId() { return roomId; } public void setRoomId(int roomId) { this.roomId = roomId; } public void setObjChatMembers(ArrayList<ChatClient> _objChatMembers) { this._objChatMembers = _objChatMembers; } public void cleanUpStreams() throws IOException{ for(ChatClient objChatClient : _objChatMembers) objChatClient.releaseStreams(); } } </code></pre> This is my ChatServer's cleanupStreams:- <pre><code>//clean up streams public void cleanUpStreams() throws IOException{ _objServerSocket.close(); for(ChatRoom objChatRoom : _objChatRooms) objChatRoom.cleanUpStreams(); } </code></pre> This is my Singleton bean which starts up as soon as application is deployed :- <pre><code>package common; import entity.UserProfile; import java.util.Date; import java.util.List; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; import javax.annotation.Resource; import javax.ejb.EJB; import javax.ejb.LocalBean; import javax.ejb.SessionContext; import javax.ejb.Singleton; import javax.ejb.Startup; import javax.ejb.Timeout; import javax.ejb.TimerService; import javax.persistence.EntityManager; import javax.persistence.PersistenceContext; import misc.ChatServer; @Startup @Singleton @LocalBean public class Global{ @EJB private EmailManagerRemote _objEmailManager; @EJB private Utils _objUtils; @Resource private SessionContext _objSessionContext; @PersistenceContext private EntityManager _objEntityManager; private TimerService _objTimerService; private ChatServer _objChatServer; @PostConstruct public void init(){ final int TWENTY_FOUR_HOURS = 1000 * 60 * 60 * 24 ; _objTimerService = _objSessionContext.getTimerService(); _objTimerService.createIntervalTimer(new Date(), TWENTY_FOUR_HOURS , null); //start chat server this._objChatServer = new ChatServer(); this._objChatServer.start(); } @Timeout public void sendBirthdayGreetingsAndBackupDatabase(){ //send birthday reminders try{ List<UserProfile> userProfileList = _objEntityManager.createNamedQuery("UserProfile.findByBirthdate").setParameter("birthdate", new Date()).getResultList(); //List<UserProfile> userProfileList = _objEntityManager.createNamedQuery("UserProfile.findAll").getResultList(); for(UserProfile objUserProfile : userProfileList) _objEmailManager.sendMail(EMAIL_TEMPLATE_CONSTANTS.REGISTRATION,objUserProfile.getUser()); } catch(Exception ex){ ex.printStackTrace(); } //backup BMS database try{ _objUtils.backupBMSDB(); } catch(Exception ex){ } } @PreDestroy public void cleanupTasks(){ try{ if(_objChatServer != null) _objChatServer.cleanUpStreams(); } catch(Exception ex){ ex.printStackTrace(); } } } </code></pre> Please ask me if anything else too is needed. This is my ChatClient's releaseStreams :- <pre><code> public void releaseStreams() throws IOException { multicastData(_objChatUser); this._objChatRoom.getObjChatMembers().remove(this); _objObjectOutputStream.close(); _objObjectInputStream.close(); _clientSocket.close(); } </code></pre>
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Can this loop take out 100% CPU?
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