1.1 --- a/src/share/vm/memory/defNewGeneration.cpp Wed Aug 06 11:57:31 2008 -0400
1.2 +++ b/src/share/vm/memory/defNewGeneration.cpp Thu Aug 21 23:36:31 2008 -0400
1.3 @@ -1,5 +1,5 @@
1.4 /*
1.5 - * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved.
1.7 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.8 *
1.9 * This code is free software; you can redistribute it and/or modify it
1.10 @@ -172,15 +172,25 @@
1.11 _to_counters = new CSpaceCounters("s1", 2, _max_survivor_size, _to_space,
1.12 _gen_counters);
1.13
1.14 - compute_space_boundaries(0);
1.15 + compute_space_boundaries(0, SpaceDecorator::Clear, SpaceDecorator::Mangle);
1.16 update_counters();
1.17 _next_gen = NULL;
1.18 _tenuring_threshold = MaxTenuringThreshold;
1.19 _pretenure_size_threshold_words = PretenureSizeThreshold >> LogHeapWordSize;
1.20 }
1.21
1.22 -void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size) {
1.23 - uintx alignment = GenCollectedHeap::heap()->collector_policy()->min_alignment();
1.24 +void DefNewGeneration::compute_space_boundaries(uintx minimum_eden_size,
1.25 + bool clear_space,
1.26 + bool mangle_space) {
1.27 + uintx alignment =
1.28 + GenCollectedHeap::heap()->collector_policy()->min_alignment();
1.29 +
1.30 + // If the spaces are being cleared (only done at heap initialization
1.31 + // currently), the survivor spaces need not be empty.
1.32 + // Otherwise, no care is taken for used areas in the survivor spaces
1.33 + // so check.
1.34 + assert(clear_space || (to()->is_empty() && from()->is_empty()),
1.35 + "Initialization of the survivor spaces assumes these are empty");
1.36
1.37 // Compute sizes
1.38 uintx size = _virtual_space.committed_size();
1.39 @@ -214,26 +224,45 @@
1.40 MemRegion fromMR((HeapWord*)from_start, (HeapWord*)to_start);
1.41 MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
1.42
1.43 - eden()->set_bounds(edenMR);
1.44 - if (minimum_eden_size == 0) {
1.45 - // The "minimum_eden_size" is really the amount of eden occupied by
1.46 - // allocated objects -- if this is zero, then we can clear the space.
1.47 - eden()->clear();
1.48 - } else {
1.49 - // Otherwise, we will not have cleared eden. This can cause newly
1.50 - // expanded space not to be mangled if using ZapUnusedHeapArea.
1.51 - // We explicitly do such mangling here.
1.52 + // A minimum eden size implies that there is a part of eden that
1.53 + // is being used and that affects the initialization of any
1.54 + // newly formed eden.
1.55 + bool live_in_eden = minimum_eden_size > 0;
1.56 +
1.57 + // If not clearing the spaces, do some checking to verify that
1.58 + // the space are already mangled.
1.59 + if (!clear_space) {
1.60 + // Must check mangling before the spaces are reshaped. Otherwise,
1.61 + // the bottom or end of one space may have moved into another
1.62 + // a failure of the check may not correctly indicate which space
1.63 + // is not properly mangled.
1.64 if (ZapUnusedHeapArea) {
1.65 - eden()->mangle_unused_area();
1.66 + HeapWord* limit = (HeapWord*) _virtual_space.high();
1.67 + eden()->check_mangled_unused_area(limit);
1.68 + from()->check_mangled_unused_area(limit);
1.69 + to()->check_mangled_unused_area(limit);
1.70 }
1.71 }
1.72 - from()->initialize(fromMR, true /* clear */);
1.73 - to()->initialize( toMR, true /* clear */);
1.74 - // Make sure we compact eden, then from.
1.75 +
1.76 + // Reset the spaces for their new regions.
1.77 + eden()->initialize(edenMR,
1.78 + clear_space && !live_in_eden,
1.79 + SpaceDecorator::Mangle);
1.80 + // If clear_space and live_in_eden, we will not have cleared any
1.81 + // portion of eden above its top. This can cause newly
1.82 + // expanded space not to be mangled if using ZapUnusedHeapArea.
1.83 + // We explicitly do such mangling here.
1.84 + if (ZapUnusedHeapArea && clear_space && live_in_eden && mangle_space) {
1.85 + eden()->mangle_unused_area();
1.86 + }
1.87 + from()->initialize(fromMR, clear_space, mangle_space);
1.88 + to()->initialize(toMR, clear_space, mangle_space);
1.89 +
1.90 + // Set next compaction spaces.
1.91 + eden()->set_next_compaction_space(from());
1.92 // The to-space is normally empty before a compaction so need
1.93 // not be considered. The exception is during promotion
1.94 // failure handling when to-space can contain live objects.
1.95 - eden()->set_next_compaction_space(from());
1.96 from()->set_next_compaction_space(NULL);
1.97 }
1.98
1.99 @@ -256,7 +285,16 @@
1.100
1.101 bool DefNewGeneration::expand(size_t bytes) {
1.102 MutexLocker x(ExpandHeap_lock);
1.103 + HeapWord* prev_high = (HeapWord*) _virtual_space.high();
1.104 bool success = _virtual_space.expand_by(bytes);
1.105 + if (success && ZapUnusedHeapArea) {
1.106 + // Mangle newly committed space immediately because it
1.107 + // can be done here more simply that after the new
1.108 + // spaces have been computed.
1.109 + HeapWord* new_high = (HeapWord*) _virtual_space.high();
1.110 + MemRegion mangle_region(prev_high, new_high);
1.111 + SpaceMangler::mangle_region(mangle_region);
1.112 + }
1.113
1.114 // Do not attempt an expand-to-the reserve size. The
1.115 // request should properly observe the maximum size of
1.116 @@ -268,7 +306,8 @@
1.117 // value.
1.118 if (GC_locker::is_active()) {
1.119 if (PrintGC && Verbose) {
1.120 - gclog_or_tty->print_cr("Garbage collection disabled, expanded heap instead");
1.121 + gclog_or_tty->print_cr("Garbage collection disabled, "
1.122 + "expanded heap instead");
1.123 }
1.124 }
1.125
1.126 @@ -332,16 +371,24 @@
1.127 changed = true;
1.128 }
1.129 if (changed) {
1.130 - compute_space_boundaries(eden()->used());
1.131 - MemRegion cmr((HeapWord*)_virtual_space.low(), (HeapWord*)_virtual_space.high());
1.132 + // The spaces have already been mangled at this point but
1.133 + // may not have been cleared (set top = bottom) and should be.
1.134 + // Mangling was done when the heap was being expanded.
1.135 + compute_space_boundaries(eden()->used(),
1.136 + SpaceDecorator::Clear,
1.137 + SpaceDecorator::DontMangle);
1.138 + MemRegion cmr((HeapWord*)_virtual_space.low(),
1.139 + (HeapWord*)_virtual_space.high());
1.140 Universe::heap()->barrier_set()->resize_covered_region(cmr);
1.141 if (Verbose && PrintGC) {
1.142 size_t new_size_after = _virtual_space.committed_size();
1.143 size_t eden_size_after = eden()->capacity();
1.144 size_t survivor_size_after = from()->capacity();
1.145 - gclog_or_tty->print("New generation size " SIZE_FORMAT "K->" SIZE_FORMAT "K [eden="
1.146 + gclog_or_tty->print("New generation size " SIZE_FORMAT "K->"
1.147 + SIZE_FORMAT "K [eden="
1.148 SIZE_FORMAT "K,survivor=" SIZE_FORMAT "K]",
1.149 - new_size_before/K, new_size_after/K, eden_size_after/K, survivor_size_after/K);
1.150 + new_size_before/K, new_size_after/K,
1.151 + eden_size_after/K, survivor_size_after/K);
1.152 if (WizardMode) {
1.153 gclog_or_tty->print("[allowed " SIZE_FORMAT "K extra for %d threads]",
1.154 thread_increase_size/K, threads_count);
1.155 @@ -486,7 +533,7 @@
1.156 ScanWeakRefClosure scan_weak_ref(this);
1.157
1.158 age_table()->clear();
1.159 - to()->clear();
1.160 + to()->clear(SpaceDecorator::Mangle);
1.161
1.162 gch->rem_set()->prepare_for_younger_refs_iterate(false);
1.163
1.164 @@ -531,8 +578,18 @@
1.165 soft_ref_policy, &is_alive, &keep_alive, &evacuate_followers, NULL);
1.166 if (!promotion_failed()) {
1.167 // Swap the survivor spaces.
1.168 - eden()->clear();
1.169 - from()->clear();
1.170 + eden()->clear(SpaceDecorator::Mangle);
1.171 + from()->clear(SpaceDecorator::Mangle);
1.172 + if (ZapUnusedHeapArea) {
1.173 + // This is now done here because of the piece-meal mangling which
1.174 + // can check for valid mangling at intermediate points in the
1.175 + // collection(s). When a minor collection fails to collect
1.176 + // sufficient space resizing of the young generation can occur
1.177 + // an redistribute the spaces in the young generation. Mangle
1.178 + // here so that unzapped regions don't get distributed to
1.179 + // other spaces.
1.180 + to()->mangle_unused_area();
1.181 + }
1.182 swap_spaces();
1.183
1.184 assert(to()->is_empty(), "to space should be empty now");
1.185 @@ -759,6 +816,15 @@
1.186 }
1.187 }
1.188
1.189 +void DefNewGeneration::reset_scratch() {
1.190 + // If contributing scratch in to_space, mangle all of
1.191 + // to_space if ZapUnusedHeapArea. This is needed because
1.192 + // top is not maintained while using to-space as scratch.
1.193 + if (ZapUnusedHeapArea) {
1.194 + to()->mangle_unused_area_complete();
1.195 + }
1.196 +}
1.197 +
1.198 bool DefNewGeneration::collection_attempt_is_safe() {
1.199 if (!to()->is_empty()) {
1.200 return false;
1.201 @@ -812,11 +878,25 @@
1.202 }
1.203 }
1.204
1.205 + if (ZapUnusedHeapArea) {
1.206 + eden()->check_mangled_unused_area_complete();
1.207 + from()->check_mangled_unused_area_complete();
1.208 + to()->check_mangled_unused_area_complete();
1.209 + }
1.210 +
1.211 // update the generation and space performance counters
1.212 update_counters();
1.213 gch->collector_policy()->counters()->update_counters();
1.214 }
1.215
1.216 +void DefNewGeneration::record_spaces_top() {
1.217 + assert(ZapUnusedHeapArea, "Not mangling unused space");
1.218 + eden()->set_top_for_allocations();
1.219 + to()->set_top_for_allocations();
1.220 + from()->set_top_for_allocations();
1.221 +}
1.222 +
1.223 +
1.224 void DefNewGeneration::update_counters() {
1.225 if (UsePerfData) {
1.226 _eden_counters->update_all();
