RFR (T) 8231395: Backout JDK-8231249

[Thomas Schatzl]

Hi,

On 24.09.19 09:43, Aleksey Shipilev wrote:
> Bug:
>   https://bugs.openjdk.java.net/browse/JDK-8231395
> 
> JDK-8231249 caused some testing failures, notably in:
>    gc/shenandoah/oom/TestClassLoaderLeak.java failed (JDK-8231389)
>    gc/shenandoah/TestAllocHumongousFragment.java
> 
> The reason is that those tests expect us to eventually come to Full GC, and JDK-8231249 prevents
> that. It requires more comprehensive fix. Let's backout the bad fix meanwhile.
> 
> Fix, produced by "hg backout"

   looks like a legit backout :) Ship it.

Thomas

> 
> diff -r ef8c8cf9256a src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
> --- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp        Fri Sep 20 10:28:48 2019 +0200
> +++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp        Tue Sep 24 09:42:57 2019 +0200
> @@ -810,10 +810,20 @@
>       // other threads have already depleted the free storage. In this case, a better
>       // strategy is to try again, as long as GC makes progress.
> -
> -    if (result == NULL) {
> -      do {
> -        control_thread()->handle_alloc_failure(req.size());
> -        result = allocate_memory_under_lock(req, in_new_region);
> -      } while (result == NULL && _progress_last_gc.is_set());
> +    //
> +    // Then, we need to make sure the allocation was retried after at least one
> +    // Full GC, which means we want to try more than ShenandoahFullGCThreshold times.
> +
> +    size_t tries = 0;
> +
> +    while (result == NULL && _progress_last_gc.is_set()) {
> +      tries++;
> +      control_thread()->handle_alloc_failure(req.size());
> +      result = allocate_memory_under_lock(req, in_new_region);
> +    }
> +
> +    while (result == NULL && tries <= ShenandoahFullGCThreshold) {
> +      tries++;
> +      control_thread()->handle_alloc_failure(req.size());
> +      result = allocate_memory_under_lock(req, in_new_region);
>       }
> 
> 
> Testing: hotspot_gc_shenandoah
>