RFR(XXS): 8234433: TestUnloadEventClassCount fails with "assert(SafepointSynchronize::is_at_safepoint()) failed: invariant"

[Per Liden]

Looks good to me! Thanks for fixing!

I manually ran the affected test with ZGC and it passes with your patch.

/Per

On 11/21/19 11:26 AM, Markus Gronlund wrote:
> Hi,
> 
> Please help review this small change:
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8234433
> Webrev: http://cr.openjdk.java.net/~mgronlun/8234433/webrev/
> Diff:
> 
> diff -r 7567ce83f3b5 -r f48ca1c7feda src/hotspot/share/jfr/jni/jfrGetAllEventClasses.cpp
> --- a/src/hotspot/share/jfr/jni/jfrGetAllEventClasses.cpp       Thu Nov 21 13:50:11 2019 +0530
> +++ b/src/hotspot/share/jfr/jni/jfrGetAllEventClasses.cpp       Thu Nov 21 11:13:34 2019 +0100
> @@ -33,12 +33,11 @@
>   #include "memory/resourceArea.hpp"
>   #include "runtime/handles.inline.hpp"
>   #include "runtime/mutexLocker.hpp"
> -#include "runtime/safepoint.hpp"
>   #include "runtime/thread.inline.hpp"
>   #include "utilities/growableArray.hpp"
>   #include "utilities/stack.inline.hpp"
> 
> - // incremented during class unloading (safepoint) for each unloaded event class
> + // incremented during class unloading for each unloaded event class
>   static jlong unloaded_event_classes = 0;
> 
>   jlong JfrEventClasses::unloaded_event_classes_count() {
> @@ -46,8 +45,7 @@
>   }
> 
>   void JfrEventClasses::increment_unloaded_event_class() {
> -  // incremented during class unloading (safepoint) for each unloaded event class
> -  assert(SafepointSynchronize::is_at_safepoint(), "invariant");
> +  assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
>     ++unloaded_event_classes;
>   }
> 
> Thanks
> Markus
>