Details
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Bug
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Resolution: Fixed
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P1
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1.1.4
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1.1.4
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generic
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generic
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Not verified
Description
ingrid.yao@Eng 1997-08-06
Oracle report the deadlock problem:
==============================================================
Have a look at the sequence of methods calls in the two deadlocked threads;
"Forms-Runform-1" and "AWT-EventQueue-0":
sun.applet.AppletClassLoader.getThreadGroup is synchronized , so the
"Forms-Runform-1" thread is waiting for the AppletClassLoader object's monitor, which is held by the "AWT-EventQueue-0" thread.
sun.applet.AppletSecurity.checkRead is synchronized, so the "AWT-EventQueue-0"
thread is waiting for the AppletSecurity object's monitor, which is held by the
"Forms-Runform-1" thread.
Each thread is blocked waiting for a monitor held by the other thread, so we have a deadlock.
Here is the stack trace and the monitor state with the irrelevant parts removed:
"Forms-Runform-1" (TID:0xf653b0, sys_thread_t:0x874580, Win32ID:0x94, stat4
sun.applet.AppletClassLoader.getThreadGroup(AppletClassLoader.java:597)
sun.applet.AppletSecurity.inThreadGroup(AppletSecurity.java:184)
sun.applet.AppletSecurity.checkAccess(AppletSecurity.java:214)
java.lang.ThreadGroup.checkAccess(ThreadGroup.java:271)
java.lang.Thread.init(Thread.java:261)
java.lang.Thread.<init>(Thread.java:393)
oracle.ewt.timer.Timer.<init>(Timer.java:35)
oracle.ewt.timer.Periodic.<init>(Periodic.java:28)
oracle.ewt.lwAWT.lwText.CursorIdler.<init>(CursorIdler.java:38)
oracle.ewt.lwAWT.lwText.CursorIdler.getCursorIdler(CursorIdler.java:50)
oracle.ewt.lwAWT.lwText.LWTextComponent.addNotify(LWTextComponent.java)
java.awt.Container.addNotify(Container.java:1083)
oracle.forms.uiClient.v1_4.ui.DrawnPanel.addNotify(DrawnPanel.java:447)
java.awt.Container.addNotify(Container.java:1083)
java.awt.Container.addNotify(Container.java:1083)
java.awt.Container.addNotify(Container.java:1083)
oracle.forms.uiClient.v1_4.ui.DrawnPanel.addNotify(DrawnPanel.java:447)
java.awt.Container.addNotify(Container.java:1083)
java.awt.Container.addNotify(Container.java:1083)
java.awt.Container.addNotify(Container.java:1083)
"AWT-EventQueue-0" (TID:0xf5ac08, sys_thread_t:0x872d90, Win32ID:0x8b, sta5
sun.applet.AppletSecurity.checkRead(AppletSecurity.java:436)
java.io.FileInputStream.<init>(FileInputStream.java:103)
java.net.SocketInputStream.<init>(SocketInputStream.java:50)
java.net.PlainSocketImpl.getInputStream(PlainSocketImpl.java:394)
java.net.Socket.getInputStream(Socket.java:290)
sun.net.www.http.HttpClient.parseHTTP(HttpClient.java:484)
sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConn)
sun.applet.AppletClassLoader.loadClass(AppletClassLoader.java:119)
sun.applet.AppletClassLoader.findClass(AppletClassLoader.java:494)
sun.applet.AppletClassLoader.loadClass(AppletClassLoader.java:197)
java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
oracle.ewt.lwAWT.SharedPainter.paint(SharedPainter.java:323)
oracle.ewt.lwAWT.BufferedFrame.paint(BufferedFrame.java:281)
oracle.ewt.lwAWT.BufferedFrame.update(BufferedFrame.java:268)
oracle.forms.uiClient.v1_4.ui.ExtendedFrame.update(ExtendedFrame.java:)
java.awt.Component.dispatchEventImpl(Component.java:1714)
java.awt.Container.dispatchEventImpl(Container.java:897)
java.awt.Window.dispatchEventImpl(Window.java:443)
java.awt.Component.dispatchEvent(Component.java:1693)
java.awt.EventDispatchThread.run(EventDispatchThread.java:63)
Monitor Cache Dump:
sun.applet.AppletSecurity@F56D08/FA8958: owner "Forms-Runform-1" (0x874580)
sun.applet.AppletClassLoader@F59D48/FB9420: owner "AWT-EventQueue-0" (0x87)
If you walk up the stack examining each method in turn, you can see that:
- The AppletSecurity object's monitor is grabbed by the "Forms-Runform-1"
thread in sun.applet.AppletSecurity.checkAccess, because it is synchronized
- The AppletClassLoader object's monitor is grabbed by the "AWT-EventQueue-0"
thread in sun.applet.AppletClassLoader.findClass, because it is synchronized.