On Wed, 20 Dec 2023 19:37:52 GMT, Kim Barrett <kbarr...@openjdk.org> wrote:
>> [JDK-8247755](https://bugs.openjdk.org/browse/JDK-8247755) introduced the >> `GrowableArrayCHeap`. This duplicates the current C-Heap allocation >> capability in `GrowableArray`. I now remove that from `GrowableArray` and >> move all usages to `GrowableArrayCHeap`. >> >> This has a few advantages: >> - Clear separation between arena (and resource area) allocating array and >> C-heap allocating array. >> - We can prevent assigning / copying between arrays of different allocation >> strategies already at compile time, and not only with asserts at runtime. >> - We should not have multiple implementations of the same thing (C-Heap >> backed array). >> - `GrowableArrayCHeap` is NONCOPYABLE. This is a nice restriction, we now >> know that C-Heap backed arrays do not get copied unknowingly. >> >> **Bonus** >> We can now restrict `GrowableArray` element type `E` to be >> `std::is_trivially_destructible<E>::value == true`. The idea is that arena / >> resource allocated arrays get abandoned, often without being even cleared. >> Hence, the elements in the array are never destructed. But if we only use >> elements that are trivially destructible, then it makes no difference if the >> destructors are ever called, or the elements simply abandoned. >> >> For `GrowableArrayCHeap`, we expect that the user eventually calls the >> destructor for the array, which in turn calls the destructors of the >> remaining elements. Hence, it is up to the user to ensure the cleanup. And >> so we can allow non-trivial destructors. >> >> **Testing** >> Tier1-3 + stress testing: pending > > src/hotspot/share/cds/metaspaceShared.cpp line 840: > >> 838: >> 839: #if INCLUDE_CDS_JAVA_HEAP >> 840: void >> VM_PopulateDumpSharedSpace::dump_java_heap_objects(GrowableArrayCHeap<Klass*, >> mtClassShared>* klasses) { > > pre-existing: Perhaps the argument should be const. pre-existing and can't attach comment to line#50: `int i;` is dead variable. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/17160#discussion_r1433116120
