From 316633bb47651f07f513982bba8153ec6d18bffd Mon Sep 17 00:00:00 2001
From: jwilhelm <unknown>
Date: Tue, 9 Jun 2015 20:10:29 +0200
Subject: [PATCH] 8086111: BACKOUT -
 metaspace/shrink_grow/CompressedClassSpaceSize fails with OOM: Compressed
 class space Reviewed-by: brutisso

---
 src/share/vm/memory/metaspace.cpp | 62 ++++---------------------------
 1 file changed, 7 insertions(+), 55 deletions(-)

diff --git a/src/share/vm/memory/metaspace.cpp b/src/share/vm/memory/metaspace.cpp
index b27a8c57f..be680218a 100644
--- a/src/share/vm/memory/metaspace.cpp
+++ b/src/share/vm/memory/metaspace.cpp
@@ -622,7 +622,8 @@ class SpaceManager : public CHeapObj<mtClass> {
   Metachunk* _chunks_in_use[NumberOfInUseLists];
   Metachunk* _current_chunk;
 
-  // Maximum number of small chunks to allocate to a SpaceManager
+  // Number of small chunks to allocate to a manager
+  // If class space manager, small chunks are unlimited
   static uint const _small_chunk_limit;
 
   // Sum of all space in allocated chunks
@@ -736,8 +737,6 @@ class SpaceManager : public CHeapObj<mtClass> {
   // Block allocation and deallocation.
   // Allocates a block from the current chunk
   MetaWord* allocate(size_t word_size);
-  // Allocates a block from a small chunk
-  MetaWord* get_small_chunk_and_allocate(size_t word_size);
 
   // Helper for allocations
   MetaWord* allocate_work(size_t word_size);
@@ -2032,8 +2031,9 @@ void SpaceManager::locked_print_chunks_in_use_on(outputStream* st) const {
 size_t SpaceManager::calc_chunk_size(size_t word_size) {
 
   // 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.
+  // _small_chunk_limit small chunks can be allocated but
+  // once a medium chunk has been allocated, no more small
+  // chunks will be allocated.
   size_t chunk_word_size;
   if (chunks_in_use(MediumIndex) == NULL &&
       sum_count_in_chunks_in_use(SmallIndex) < _small_chunk_limit) {
@@ -2101,7 +2101,7 @@ MetaWord* SpaceManager::grow_and_allocate(size_t word_size) {
                             word_size, words_used, words_left);
   }
 
-  // Get another chunk
+  // Get another chunk out of the virtual space
   size_t grow_chunks_by_words = calc_chunk_size(word_size);
   Metachunk* next = get_new_chunk(word_size, grow_chunks_by_words);
 
@@ -2432,43 +2432,6 @@ Metachunk* SpaceManager::get_new_chunk(size_t word_size,
   return next;
 }
 
-/*
- * The policy is to allocate up to _small_chunk_limit small chunks
- * after which only medium chunks are allocated.  This is done to
- * reduce fragmentation.  In some cases, this can result in a lot
- * of small chunks being allocated to the point where it's not
- * possible to expand.  If this happens, there may be no medium chunks
- * available and OOME would be thrown.  Instead of doing that,
- * if the allocation request size fits in a small chunk, an attempt
- * will be made to allocate a small chunk.
- */
-MetaWord* SpaceManager::get_small_chunk_and_allocate(size_t word_size) {
-  if (word_size + Metachunk::overhead() > small_chunk_size()) {
-    return NULL;
-  }
-
-  MutexLockerEx cl(lock(), Mutex::_no_safepoint_check_flag);
-  MutexLockerEx cl1(expand_lock(), Mutex::_no_safepoint_check_flag);
-
-  Metachunk* chunk = chunk_manager()->chunk_freelist_allocate(small_chunk_size());
-
-  MetaWord* mem = NULL;
-
-  if (chunk != NULL) {
-    // Add chunk to the in-use chunk list and do an allocation from it.
-    // Add to this manager's list of chunks in use.
-    add_chunk(chunk, false);
-    mem = chunk->allocate(word_size);
-
-    inc_used_metrics(word_size);
-
-    // Track metaspace memory usage statistic.
-    track_metaspace_memory_usage();
-  }
-
-  return mem;
-}
-
 MetaWord* SpaceManager::allocate(size_t word_size) {
   MutexLockerEx cl(lock(), Mutex::_no_safepoint_check_flag);
 
@@ -3548,18 +3511,7 @@ MetaWord* Metaspace::allocate(ClassLoaderData* loader_data, size_t word_size,
   }
 
   if (result == NULL) {
-    SpaceManager* sm;
-    if (is_class_space_allocation(mdtype)) {
-      sm = loader_data->metaspace_non_null()->class_vsm();
-    } else {
-      sm = loader_data->metaspace_non_null()->vsm();
-    }
-
-    result = sm->get_small_chunk_and_allocate(word_size);
-
-    if (result == NULL) {
-      report_metadata_oome(loader_data, word_size, type, mdtype, CHECK_NULL);
-    }
+    report_metadata_oome(loader_data, word_size, type, mdtype, CHECK_NULL);
   }
 
   // Zero initialize.
-- 
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