RFR: 8259008: ArithmeticException was thrown at "Monitor Cache Dump" on HSDB

[David Holmes]

On Wed, 30 Dec 2020 13:51:04 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

> I saw the exception as following when I chose "Monitor Cache Dump" menu on HSDB:
> 
> Exception in thread "AWT-EventQueue-0" java.lang.ExceptionInInitializerError
>         at jdk.hotspot.agent/sun.jvm.hotspot.ui.MonitorCacheDumpPanel.dumpOn(MonitorCacheDumpPanel.java:92)
>         at jdk.hotspot.agent/sun.jvm.hotspot.ui.MonitorCacheDumpPanel.<init>(MonitorCacheDumpPanel.java:59)
>         at jdk.hotspot.agent/sun.jvm.hotspot.HSDB.showMonitorCacheDumpPanel(HSDB.java:1556)
>         at jdk.hotspot.agent/sun.jvm.hotspot.HSDB$16.actionPerformed(HSDB.java:338)
>         at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1972)
>         at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2313)
>         at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
>         at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
>         at java.desktop/javax.swing.AbstractButton.doClick(AbstractButton.java:374)
>         at java.desktop/javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1022)
>         at java.desktop/javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1066)
>         at java.desktop/java.awt.Component.processMouseEvent(Component.java:6617)
>         at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
>         at java.desktop/java.awt.Component.processEvent(Component.java:6382)
>         at java.desktop/java.awt.Container.processEvent(Container.java:2264)
>         at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4993)
>         at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2322)
>         at java.desktop/java.awt.Component.dispatchEvent(Component.java:4825)
>         at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4934)
>         at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4563)
>         at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4504)
>         at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2308)
>         at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2773)
>         at java.desktop/java.awt.Component.dispatchEvent(Component.java:4825)
>         at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
>         at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
>         at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
>         at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
>         at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
>         at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
>         at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
>         at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
>         at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
>         at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
>         at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
>         at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
>         at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
>         at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
>         at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
>         at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
>         at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
> Caused by: java.lang.ArithmeticException: / by zero
>         at jdk.hotspot.agent/sun.jvm.hotspot.runtime.ObjectSynchronizer.initialize(ObjectSynchronizer.java:55)
>         at jdk.hotspot.agent/sun.jvm.hotspot.runtime.ObjectSynchronizer$1.update(ObjectSynchronizer.java:40)
>         at jdk.hotspot.agent/sun.jvm.hotspot.runtime.VM.registerVMInitializedObserver(VM.java:578)
>         at jdk.hotspot.agent/sun.jvm.hotspot.runtime.ObjectSynchronizer.<clinit>(ObjectSynchronizer.java:38)
>         ... 41 more
> 
> This exception seems to be caused by [JDK-8253064](https://bugs.openjdk.java.net/browse/JDK-8253064). It has changed `ObjectSynchronizer`, but it has not changed SA code.

Hi Yasumasa,

So this makes MonitorList, MonitorList::Iterator and ObjectSynchronizer::_in_use_list, exported top-level entities so that SA can use them as a replacement for the old gBlockList. This seems quite reasonable to me, but @dcubed-ojdk should confirm that.

A couple of minor comments below.

Thanks,
David

test/hotspot/jtreg/serviceability/sa/TestObjectMonitorIterate.java line 52:

> 50:         HotSpotAgent agent = new HotSpotAgent();
> 51:         try {
> 52:             agent.attach(Integer.parseInt(pid));

This should be outside the try block else you will call detach even if attach fails.

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/runtime/ObjectSynchronizer.java line 97:

> 95:     ObjectMonitorIterator() {
> 96:       headAddr = inUseList;
> 97:       block = new ObjectMonitor(headAddr);

The "block" terminology doesn't really make sense any more.

-------------

Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1910