src/hotspot/share/memory/metaspace/spaceManager.cpp

rev 58565 : 8238358: Implementation of JEP 371: Hidden Classes
Reviewed-by: duke
Contributed-by: mandy.chung@oracle.com, lois.foltan@oracle.com, david.holmes@oracle.com, harold.seigel@oracle.com, serguei.spitsyn@oracle.com, alex.buckley@oracle.com, jamsheed.c.m@oracle.com

*** 1,7 ****
  /*
!  * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
--- 1,7 ----
  /*
!  * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
*** 73,90 ****
    size_t requested;
  
    if (is_class()) {
      switch (type) {
      case Metaspace::BootMetaspaceType:              requested = Metaspace::first_class_chunk_word_size(); break;
!     case Metaspace::UnsafeAnonymousMetaspaceType:   requested = ClassSpecializedChunk; break;
      case Metaspace::ReflectionMetaspaceType:        requested = ClassSpecializedChunk; break;
      default:                                        requested = ClassSmallChunk; break;
      }
    } else {
      switch (type) {
      case Metaspace::BootMetaspaceType:              requested = Metaspace::first_chunk_word_size(); break;
!     case Metaspace::UnsafeAnonymousMetaspaceType:   requested = SpecializedChunk; break;
      case Metaspace::ReflectionMetaspaceType:        requested = SpecializedChunk; break;
      default:                                        requested = SmallChunk; break;
      }
    }
  
--- 73,90 ----
    size_t requested;
  
    if (is_class()) {
      switch (type) {
      case Metaspace::BootMetaspaceType:              requested = Metaspace::first_class_chunk_word_size(); break;
!     case Metaspace::ClassMirrorHolderMetaspaceType: requested = ClassSpecializedChunk; break;
      case Metaspace::ReflectionMetaspaceType:        requested = ClassSpecializedChunk; break;
      default:                                        requested = ClassSmallChunk; break;
      }
    } else {
      switch (type) {
      case Metaspace::BootMetaspaceType:              requested = Metaspace::first_chunk_word_size(); break;
!     case Metaspace::ClassMirrorHolderMetaspaceType: requested = SpecializedChunk; break;
      case Metaspace::ReflectionMetaspaceType:        requested = SpecializedChunk; break;
      default:                                        requested = SmallChunk; break;
      }
    }
  
*** 112,130 ****
    // Decide between a small chunk and a medium chunk.  Up to
    // _small_chunk_limit small chunks can be allocated.
    // After that a medium chunk is preferred.
    size_t chunk_word_size;
  
!   // Special case for unsafe anonymous metadata space.
!   // UnsafeAnonymous metadata space is usually small since it is used for
!   // class loader data's whose life cycle is governed by one class such as an
!   // unsafe anonymous class.  The majority within 1K - 2K range and
    // rarely about 4K (64-bits JVM).
    // Instead of jumping to SmallChunk after initial chunk exhausted, keeping allocation
    // from SpecializeChunk up to _anon_or_delegating_metadata_specialize_chunk_limit (4)
    // reduces space waste from 60+% to around 30%.
!   if ((_space_type == Metaspace::UnsafeAnonymousMetaspaceType || _space_type == Metaspace::ReflectionMetaspaceType) &&
        _mdtype == Metaspace::NonClassType &&
        num_chunks_by_type(SpecializedIndex) < anon_and_delegating_metadata_specialize_chunk_limit &&
        word_size + Metachunk::overhead() <= SpecializedChunk) {
      return SpecializedChunk;
    }
--- 112,130 ----
    // Decide between a small chunk and a medium chunk.  Up to
    // _small_chunk_limit small chunks can be allocated.
    // After that a medium chunk is preferred.
    size_t chunk_word_size;
  
!   // Special case for hidden metadata space.
!   // ClassMirrorHolder metadata space is usually small since it is used for
!   // class loader data's whose life cycle is governed by one class such as a
!   // weak hidden or unsafe anonymous class.  The majority within 1K - 2K range and
    // rarely about 4K (64-bits JVM).
    // Instead of jumping to SmallChunk after initial chunk exhausted, keeping allocation
    // from SpecializeChunk up to _anon_or_delegating_metadata_specialize_chunk_limit (4)
    // reduces space waste from 60+% to around 30%.
!   if ((_space_type == Metaspace::ClassMirrorHolderMetaspaceType || _space_type == Metaspace::ReflectionMetaspaceType) &&
        _mdtype == Metaspace::NonClassType &&
        num_chunks_by_type(SpecializedIndex) < anon_and_delegating_metadata_specialize_chunk_limit &&
        word_size + Metachunk::overhead() <= SpecializedChunk) {
      return SpecializedChunk;
    }