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Netbeans 6.8 (no updates applied) JDK 6 update 18 32-bit When I run my application under the profiler I see the following warnings: *** Profiler engine warning: class sun.reflect.GeneratedSerializationConstructorAccessor1 that should be instrumented is not loaded by target VM *** Requested classloader: sun.reflect.DelegatingClassLoader@f3ce62, its class = class sun.reflect.DelegatingClassLoader, index = 4, hashcode = 15978082 *** Profiler engine warning: target VM cannot load class to instrument sun.reflect.GeneratedSerializationConstructorAccessor1 *** probably it has been unloaded recently Later on, I hit the "take snapshot" button and the JVM crashes. I don't know if the two are related but I thought I would mention it because I believe Netbeans used to have special handling for "sun.reflect.GeneratedSerializationConstructorAccessor*" in the past but it no longer seems to. Please see the attached logs and let me know if you need any more information. PS: I am using "Profile main application".
Created attachment 96249 [details] normal stdout output
Created attachment 96250 [details] stdout output with JVM -verbose option
Created attachment 96251 [details] JVM crash log
Created attachment 96252 [details] Netbeans messages log
You can reproduce the problem with for following simple testcase: public class Main { public static void main(String[] args) throws InterruptedException { while (true) { Thread.sleep(1000); } } } The key seems to be to enable "Record stack trace for allocations". The crash goes away with this feature disabled.
Upon further examination, I suspect these are two separate issues: 1. sun.reflect.GeneratedSerializationConstructorAccessor warnings are probably a Netbeans issue. 2. The crash is probably a JVM issue.
Profiler engine warning should be harmless. The JVM crash looks similar to issue #62919. Can try to reproduce it on latest JDK7 build (https://jdk7.dev.java.net/). You try workaround from issue #62919 - run your profiled application with JVM option -Xnoclassgc
I am not able to reproduce it on Windows 7 64bit, with 32bit JDK 1.6.0_18 and NetBeans 6.8. I used memory profiling with allocation stack traces and I used your testcase.
Thomas, Was bug #62919 ever fixed in the JDK? Or did you only work around it in Netbeans? Regarding this bug: 1. You must launch memory profiling with "Record both object creations and garbage collection" and "record stack trace for allocations". The default "Record object creations only" will not do it. 2. This problem does not occur under JDK7 b87. In spite of #2, I hope that you agree that this needs to be fixed in Java6.
I was able to reproduce it. It looks like a JVM problem, which is different from issue #62919.
Tomas, Do you plan on filing a bug report against the JDK?
Yes, once I know what is going on. I am still investigating it.
There is an easy workaround - create custom configuration and uncheck 'Run garbage collection when getting memory results' in Advanced settings. Lowering priority to P2.
Problem reported as JDK bug #6949515
Closing as wontfix. The crash is caused by JDK bug. The fix for the JDK bug is in progress and the bug will be fixed in OpenJDK 6, JDK 7 and it will be back-ported to JDK 6 update release. Until the problem is fixed in JDK, please, use JDK 6u17 or use workaround from comment #13.
Any idea why JDK bug #6949515 isn't visible on BugParade? It's been a long time since it was filed.
JDK bug #6949515 is fixed in 1.6.0_21, which was released on July 7th 2010.
I encountered the same problem with netbean 6.9, i.e the same error message, and same output message telling cannot load some classes...
Apparently, the bug is not fixed properly. JDK 6u21 crashes every time I try to dynamically attach the profiler to it. Both NetBeans and the WebLogic server run on JDK 6u21. -- NetBeans 6.9 JDK 6u21 Windows XP Professional (version 2002) (32-bit), Service Pack 3 Intel Core 2 Quad CPU -- # # A fatal error has been detected by the Java Runtime Environment: # # EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x6d951e2b, pid=2224, tid=1572 # # JRE version: 6.0_21-b06 # Java VM: Java HotSpot(TM) Client VM (17.0-b16 mixed mode windows-x86 ) # Problematic frame: # V [jvm.dll+0xa1e2b] # # If you would like to submit a bug report, please visit: # http://java.sun.com/webapps/bugreport/crash.jsp # --------------- T H R E A D --------------- Current thread (0x45f32800): JavaThread "*** Profiler Agent Special Execution Thread 2" daemon [_thread_in_vm, id=1572, stack(0x48300000,0x48350000)] siginfo: ExceptionCode=0xc0000005, reading address 0x00000004 ...
(In reply to comment #19) > Apparently, the bug is not fixed properly. JDK 6u21 crashes every time I try to > dynamically attach the profiler to it. Both NetBeans and the WebLogic server > run on JDK 6u21. This is probably something different. Please open new bug.