RFR (XS) 8224880: ShenandoahRootScanner::roots_do assert is too strong

[Zhengyu Gu]

On 5/29/19 7:19 AM, Aleksey Shipilev wrote:
> Bug:
>    https://bugs.openjdk.java.net/browse/JDK-8224970
> 
> It reliably happens with x86_32 and gc/shenandoah/oom tests that enter the heap inspection on OOM.
> That operation is done under its own VM op. So, the fix is to relax the assert to accept
> non-Shenandoah safepoints.
> 
> diff -r 785a12e0f89b src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.inline.hpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.inline.hpp        Wed May 29 12:01:21
> 2019 +0200
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.inline.hpp        Wed May 29 12:57:03
> 2019 +0200
> @@ -28,4 +28,5 @@
>   #include "gc/shenandoah/shenandoahRootProcessor.hpp"
>   #include "gc/shenandoah/shenandoahTimingTracker.hpp"
> +#include "gc/shenandoah/shenandoahUtils.hpp"
>   #include "memory/resourceArea.hpp"
> 
> @@ -91,7 +92,8 @@
>   template <typename ITR>
>   void ShenandoahRootScanner<ITR>::roots_do(uint worker_id, OopClosure* oops, CLDClosure* clds,
> CodeBlobClosure* code, ThreadClosure *tc) {
> -  assert(!ShenandoahHeap::heap()->unload_classes() ||
> +  assert(!ShenandoahSafepoint::is_at_shenandoah_safepoint() ||
> +         !ShenandoahHeap::heap()->unload_classes() ||
>             ShenandoahHeap::heap()->heuristics()->can_do_traversal_gc(),
> -          "No class unloading or traversal GC");
> +          "Expect class unloading or traversal when Shenandoah cycle is running");
>     ShenandoahParallelOopsDoThreadClosure tc_cl(oops, code, tc);
>     ResourceMark rm;
Okay.

-Zhengyu

> 
> 
> Testing: hotspot_gc_shenandoah + failing test
>