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href="/tags/Lowest-Common-Ancestor-of-a-Binary-Tree/" rel="tag">Lowest Common Ancestor of a Binary Tree</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/MQ/" rel="tag">MQ</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Mac/" rel="tag">Mac</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Maven/" rel="tag">Maven</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Mybatis/" rel="tag">Mybatis</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Mysql/" rel="tag">Mysql</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/NameServer/" rel="tag">NameServer</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/PHP/" rel="tag">PHP</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Preorder-Traversal/" rel="tag">Preorder Traversal</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/RPC/" rel="tag">RPC</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Redis/" rel="tag">Redis</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/RocketMQ/" rel="tag">RocketMQ</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Rotate-Image/" rel="tag">Rotate Image</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Rust/" rel="tag">Rust</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/SPI/" rel="tag">SPI</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Servlet/" rel="tag">Servlet</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Singleton/" rel="tag">Singleton</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Spring/" rel="tag">Spring</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/SpringBoot/" rel="tag">SpringBoot</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Sql%E6%B3%A8%E5%85%A5/" rel="tag">Sql注入</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Stream/" rel="tag">Stream</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Synchronized/" rel="tag">Synchronized</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Thread-dump/" rel="tag">Thread dump</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/ThreadLocal/" rel="tag">ThreadLocal</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/ThreadPool/" rel="tag">ThreadPool</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Tomcat/" rel="tag">Tomcat</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Trapping-Rain-Water/" rel="tag">Trapping Rain Water</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/WeakReference/" rel="tag">WeakReference</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Web/" rel="tag">Web</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/Webhook/" rel="tag">Webhook</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/aqs/" rel="tag">aqs</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/await/" rel="tag">await</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/bloom-filter/" rel="tag">bloom filter</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/c/" rel="tag">c++</a><span class="tag-list-count">14</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/cgroup/" rel="tag">cgroup</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/cluster/" rel="tag">cluster</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/condition/" rel="tag">condition</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/docker/" rel="tag">docker</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/dp/" rel="tag">dp</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/echo/" rel="tag">echo</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/environment/" rel="tag">environment</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/gap-lock/" rel="tag">gap lock</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/gc/" rel="tag">gc</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/grep/" rel="tag">grep</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/hadoop/" rel="tag">hadoop</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/icu4c/" rel="tag">icu4c</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/im/" rel="tag">im</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/is-not-null/" rel="tag">is not null</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/is-null/" rel="tag">is null</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/j-u-c/" rel="tag">j.u.c</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/java/" rel="tag">java</a><span class="tag-list-count">16</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/jvm/" rel="tag">jvm</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/leetcode/" rel="tag">leetcode</a><span class="tag-list-count">25</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/leetcode-155/" rel="tag">leetcode 155</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/linked-list/" rel="tag">linked list</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/linux/" rel="tag">linux</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/lock/" rel="tag">lock</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mfc/" rel="tag">mfc</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/min-stack/" rel="tag">min stack</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mq/" rel="tag">mq</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mvcc/" rel="tag">mvcc</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/mysql/" rel="tag">mysql</a><span class="tag-list-count">5</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/namespace/" rel="tag">namespace</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/next-key-lock/" rel="tag">next-key lock</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/nginx/" rel="tag">nginx</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/nullsfirst/" rel="tag">nullsfirst</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/openresty/" rel="tag">openresty</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/php/" rel="tag">php</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/procedure/" rel="tag">procedure</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/python/" rel="tag">python</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/read-view/" rel="tag">read view</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/redis/" rel="tag">redis</a><span class="tag-list-count">8</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/signal/" rel="tag">signal</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/sort/" rel="tag">sort</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/spark/" rel="tag">spark</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/stack/" rel="tag">stack</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/string/" rel="tag">string</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/swoole/" rel="tag">swoole</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/top/" rel="tag">top</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/uname/" rel="tag">uname</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/unlock/" rel="tag">unlock</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/value/" rel="tag">value</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/websocket/" rel="tag">websocket</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/zsh/" rel="tag">zsh</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%89%E9%98%B6%E6%AE%B5%E6%8F%90%E4%BA%A4/" rel="tag">三阶段提交</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%8D%E5%8F%AF%E5%8F%98%E5%BC%95%E7%94%A8/" rel="tag">不可变引用</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%A4%E9%98%B6%E6%AE%B5%E6%8F%90%E4%BA%A4/" rel="tag">两阶段提交</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%AD%E5%B1%B1%E8%B7%AF/" rel="tag">中山路</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%AD%E5%BA%8F/" rel="tag">中序</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%B8%AD%E9%97%B4%E4%BB%B6/" rel="tag">中间件</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BA%8C%E5%8F%89%E6%A0%91/" rel="tag">二叉树</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BA%92%E6%96%A5%E9%94%81/" rel="tag">互斥锁</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BB%A3%E7%A0%81%E9%A2%98%E8%A7%A3/" rel="tag">代码题解</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E4%BF%AE%E7%94%B5%E8%84%91%E7%9A%84/" rel="tag">修电脑的</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%81%8F%E5%90%91%E9%94%81/" rel="tag">偏向锁</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%81%A5%E5%BA%B7%E7%A0%81/" rel="tag">健康码</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%85%AC%E4%BA%A4/" rel="tag">公交</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%85%AC%E4%BA%A4%E8%BD%A6/" rel="tag">公交车</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%86%85%E5%AD%98%E5%88%86%E5%B8%83/" rel="tag">内存分布</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%86%85%E5%AD%98%E6%B3%84%E6%BC%8F/" rel="tag">内存泄漏</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%87%86%E5%A4%87/" rel="tag">准备</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%87%8F%E8%82%A5/" rel="tag">减肥</a><span class="tag-list-count">6</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%86%E5%B8%83%E5%BC%8F%E4%BA%8B%E5%8A%A1/" rel="tag">分布式事务</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%86%E5%B8%83%E5%BC%8F%E9%94%81/" rel="tag">分布式锁</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%87%E7%89%87/" rel="tag">切片</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%88%9D%E5%A7%8B%E5%8C%96/" rel="tag">初始化</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%89%8A%E5%B3%B0%E5%A1%AB%E8%B0%B7/" rel="tag">削峰填谷</a><span class="tag-list-count">4</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%89%8D%E5%BA%8F/" rel="tag">前序</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8A%A0%E5%A1%9E/" rel="tag">加塞</a><span class="tag-list-count">3</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8A%A0%E8%BD%BD/" rel="tag">加载</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8D%95%E4%BE%8B/" rel="tag">单例</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8D%9A%E5%AE%A2%EF%BC%8C%E6%96%87%E7%AB%A0/" rel="tag">博客,文章</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8E%A6%E9%97%A8/" rel="tag">厦门</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%8C%E4%BA%B2%E5%A7%94%E6%B4%BE/" rel="tag">双亲委派</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%91%E8%A1%8C%E7%89%88/" rel="tag">发行版</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%A3%E7%BD%A9/" rel="tag">口罩</a><span class="tag-list-count">1</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%8F%AF%E5%8F%98%E5%BC%95%E7%94%A8/" rel="tag">可变引用</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%90%90%E6%A7%BD/" rel="tag">吐槽</a><span class="tag-list-count">2</span></li><li class="tag-list-item"><a class="tag-list-link" href="/tags/%E5%9E%83%E5%9C%BE%E5%9B%9E%E6%94%B6/" rel="tag">垃圾回收</a><span 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<span id="/2019/12/07/JVM-G1-Part-1/" class="post-meta-item leancloud_visitors" data-flag-title="JVM源码分析之G1垃圾收集器分析一" title="Views">
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<p>对 Java 的 gc 实现比较感兴趣,原先一般都是看周志明的书,但其实并没有讲具体的 gc 源码,而是把整个思路和流程讲解了一下<br>特别是 G1 的具体实现<br>一般对 G1 的理解其实就是把原先整块的新生代老年代分成了以 region 为单位的小块内存,简而言之,就是原先对新生代老年代的收集会涉及到整个代的堆内存空间,而G1 把它变成了更细致的小块内存<br>这带来了一个很明显的好处和一个很明显的坏处,好处是内存收集可以更灵活,耗时会变短,但整个收集的处理复杂度就变高了<br>目前看了一点点关于 G1 收集的预期时间相关的代码</p>
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<pre class="line-numbers language-C++" data-language="C++"><code class="language-C++">HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
|
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|
uint gc_count_before,
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bool* succeeded,
|
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GCCause::Cause gc_cause) {
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assert_heap_not_locked_and_not_at_safepoint();
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VM_G1CollectForAllocation op(word_size,
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|
gc_count_before,
|
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|
gc_cause,
|
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false, /* should_initiate_conc_mark */
|
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|
g1_policy()->max_pause_time_ms());
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VMThread::execute(&op);
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HeapWord* result = op.result();
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bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
|
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|
assert(result == NULL || ret_succeeded,
|
|
|
"the result should be NULL if the VM did not succeed");
|
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*succeeded = ret_succeeded;
|
|
|
|
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|
assert_heap_not_locked();
|
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return result;
|
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}<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>
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<p>这里就是收集时需要停顿的,其中<code>VMThread::execute(&op);</code>是具体执行的,真正执行的是<code>VM_G1CollectForAllocation::doit</code>方法</p>
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<pre class="line-numbers language-C++" data-language="C++"><code class="language-C++">void VM_G1CollectForAllocation::doit() {
|
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G1CollectedHeap* g1h = G1CollectedHeap::heap();
|
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|
assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
|
|
|
"only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
|
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|
|
|
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if (_word_size > 0) {
|
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|
// An allocation has been requested. So, try to do that first.
|
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_result = g1h->attempt_allocation_at_safepoint(_word_size,
|
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|
false /* expect_null_cur_alloc_region */);
|
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|
if (_result != NULL) {
|
|
|
// If we can successfully allocate before we actually do the
|
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|
// pause then we will consider this pause successful.
|
|
|
_pause_succeeded = true;
|
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|
return;
|
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|
}
|
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}
|
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GCCauseSetter x(g1h, _gc_cause);
|
|
|
if (_should_initiate_conc_mark) {
|
|
|
// It's safer to read old_marking_cycles_completed() here, given
|
|
|
// that noone else will be updating it concurrently. Since we'll
|
|
|
// only need it if we're initiating a marking cycle, no point in
|
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|
// setting it earlier.
|
|
|
_old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
|
|
|
|
|
|
// At this point we are supposed to start a concurrent cycle. We
|
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|
// will do so if one is not already in progress.
|
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bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
|
|
|
|
|
|
// The above routine returns true if we were able to force the
|
|
|
// next GC pause to be an initial mark; it returns false if a
|
|
|
// marking cycle is already in progress.
|
|
|
//
|
|
|
// If a marking cycle is already in progress just return and skip the
|
|
|
// pause below - if the reason for requesting this initial mark pause
|
|
|
// was due to a System.gc() then the requesting thread should block in
|
|
|
// doit_epilogue() until the marking cycle is complete.
|
|
|
//
|
|
|
// If this initial mark pause was requested as part of a humongous
|
|
|
// allocation then we know that the marking cycle must just have
|
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|
// been started by another thread (possibly also allocating a humongous
|
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// object) as there was no active marking cycle when the requesting
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// thread checked before calling collect() in
|
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// attempt_allocation_humongous(). Retrying the GC, in this case,
|
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// will cause the requesting thread to spin inside collect() until the
|
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|
// just started marking cycle is complete - which may be a while. So
|
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// we do NOT retry the GC.
|
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|
if (!res) {
|
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|
assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
|
|
|
if (_gc_cause != GCCause::_g1_humongous_allocation) {
|
|
|
_should_retry_gc = true;
|
|
|
}
|
|
|
return;
|
|
|
}
|
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|
}
|
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|
// Try a partial collection of some kind.
|
|
|
_pause_succeeded = g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
|
|
|
|
|
|
if (_pause_succeeded) {
|
|
|
if (_word_size > 0) {
|
|
|
// An allocation had been requested. Do it, eventually trying a stronger
|
|
|
// kind of GC.
|
|
|
_result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);
|
|
|
} else {
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|
bool should_upgrade_to_full = !g1h->should_do_concurrent_full_gc(_gc_cause) &&
|
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|
!g1h->has_regions_left_for_allocation();
|
|
|
if (should_upgrade_to_full) {
|
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|
// There has been a request to perform a GC to free some space. We have no
|
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|
// information on how much memory has been asked for. In case there are
|
|
|
// absolutely no regions left to allocate into, do a maximally compacting full GC.
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|
log_info(gc, ergo)("Attempting maximally compacting collection");
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|
_pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
|
|
|
true /* clear_all_soft_refs */);
|
|
|
}
|
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|
}
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|
guarantee(_pause_succeeded, "Elevated collections during the safepoint must always succeed.");
|
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|
} else {
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|
assert(_result == NULL, "invariant");
|
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|
// The only reason for the pause to not be successful is that, the GC locker is
|
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|
// active (or has become active since the prologue was executed). In this case
|
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|
// we should retry the pause after waiting for the GC locker to become inactive.
|
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|
_should_retry_gc = true;
|
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|
}
|
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|
}<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>
|
|
|
<p>这里可以看到核心的是<code>G1CollectedHeap::do_collection_pause_at_safepoint</code>这个方法,它带上了目标暂停时间的值</p>
|
|
|
<pre class="line-numbers language-C++" data-language="C++"><code class="language-C++">G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
|
|
|
assert_at_safepoint_on_vm_thread();
|
|
|
guarantee(!is_gc_active(), "collection is not reentrant");
|
|
|
|
|
|
if (GCLocker::check_active_before_gc()) {
|
|
|
return false;
|
|
|
}
|
|
|
|
|
|
_gc_timer_stw->register_gc_start();
|
|
|
|
|
|
GCIdMark gc_id_mark;
|
|
|
_gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
|
|
|
|
|
|
SvcGCMarker sgcm(SvcGCMarker::MINOR);
|
|
|
ResourceMark rm;
|
|
|
|
|
|
g1_policy()->note_gc_start();
|
|
|
|
|
|
wait_for_root_region_scanning();
|
|
|
|
|
|
print_heap_before_gc();
|
|
|
print_heap_regions();
|
|
|
trace_heap_before_gc(_gc_tracer_stw);
|
|
|
|
|
|
_verifier->verify_region_sets_optional();
|
|
|
_verifier->verify_dirty_young_regions();
|
|
|
|
|
|
// We should not be doing initial mark unless the conc mark thread is running
|
|
|
if (!_cm_thread->should_terminate()) {
|
|
|
// This call will decide whether this pause is an initial-mark
|
|
|
// pause. If it is, in_initial_mark_gc() will return true
|
|
|
// for the duration of this pause.
|
|
|
g1_policy()->decide_on_conc_mark_initiation();
|
|
|
}
|
|
|
|
|
|
// We do not allow initial-mark to be piggy-backed on a mixed GC.
|
|
|
assert(!collector_state()->in_initial_mark_gc() ||
|
|
|
collector_state()->in_young_only_phase(), "sanity");
|
|
|
|
|
|
// We also do not allow mixed GCs during marking.
|
|
|
assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
|
|
|
|
|
|
// Record whether this pause is an initial mark. When the current
|
|
|
// thread has completed its logging output and it's safe to signal
|
|
|
// the CM thread, the flag's value in the policy has been reset.
|
|
|
bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
|
|
|
|
|
|
// Inner scope for scope based logging, timers, and stats collection
|
|
|
{
|
|
|
EvacuationInfo evacuation_info;
|
|
|
|
|
|
if (collector_state()->in_initial_mark_gc()) {
|
|
|
// We are about to start a marking cycle, so we increment the
|
|
|
// full collection counter.
|
|
|
increment_old_marking_cycles_started();
|
|
|
_cm->gc_tracer_cm()->set_gc_cause(gc_cause());
|
|
|
}
|
|
|
|
|
|
_gc_tracer_stw->report_yc_type(collector_state()->yc_type());
|
|
|
|
|
|
GCTraceCPUTime tcpu;
|
|
|
|
|
|
G1HeapVerifier::G1VerifyType verify_type;
|
|
|
FormatBuffer<> gc_string("Pause Young ");
|
|
|
if (collector_state()->in_initial_mark_gc()) {
|
|
|
gc_string.append("(Concurrent Start)");
|
|
|
verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
|
|
|
} else if (collector_state()->in_young_only_phase()) {
|
|
|
if (collector_state()->in_young_gc_before_mixed()) {
|
|
|
gc_string.append("(Prepare Mixed)");
|
|
|
} else {
|
|
|
gc_string.append("(Normal)");
|
|
|
}
|
|
|
verify_type = G1HeapVerifier::G1VerifyYoungNormal;
|
|
|
} else {
|
|
|
gc_string.append("(Mixed)");
|
|
|
verify_type = G1HeapVerifier::G1VerifyMixed;
|
|
|
}
|
|
|
GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
|
|
|
|
|
|
uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
|
|
|
workers()->active_workers(),
|
|
|
Threads::number_of_non_daemon_threads());
|
|
|
active_workers = workers()->update_active_workers(active_workers);
|
|
|
log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
|
|
|
|
|
|
TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
|
|
|
TraceMemoryManagerStats tms(&_memory_manager, gc_cause(),
|
|
|
collector_state()->yc_type() == Mixed /* allMemoryPoolsAffected */);
|
|
|
|
|
|
G1HeapTransition heap_transition(this);
|
|
|
size_t heap_used_bytes_before_gc = used();
|
|
|
|
|
|
// Don't dynamically change the number of GC threads this early. A value of
|
|
|
// 0 is used to indicate serial work. When parallel work is done,
|
|
|
// it will be set.
|
|
|
|
|
|
{ // Call to jvmpi::post_class_unload_events must occur outside of active GC
|
|
|
IsGCActiveMark x;
|
|
|
|
|
|
gc_prologue(false);
|
|
|
|
|
|
if (VerifyRememberedSets) {
|
|
|
log_info(gc, verify)("[Verifying RemSets before GC]");
|
|
|
VerifyRegionRemSetClosure v_cl;
|
|
|
heap_region_iterate(&v_cl);
|
|
|
}
|
|
|
|
|
|
_verifier->verify_before_gc(verify_type);
|
|
|
|
|
|
_verifier->check_bitmaps("GC Start");
|
|
|
|
|
|
#if COMPILER2_OR_JVMCI
|
|
|
DerivedPointerTable::clear();
|
|
|
#endif
|
|
|
|
|
|
// Please see comment in g1CollectedHeap.hpp and
|
|
|
// G1CollectedHeap::ref_processing_init() to see how
|
|
|
// reference processing currently works in G1.
|
|
|
|
|
|
// Enable discovery in the STW reference processor
|
|
|
_ref_processor_stw->enable_discovery();
|
|
|
|
|
|
{
|
|
|
// We want to temporarily turn off discovery by the
|
|
|
// CM ref processor, if necessary, and turn it back on
|
|
|
// on again later if we do. Using a scoped
|
|
|
// NoRefDiscovery object will do this.
|
|
|
NoRefDiscovery no_cm_discovery(_ref_processor_cm);
|
|
|
|
|
|
// Forget the current alloc region (we might even choose it to be part
|
|
|
// of the collection set!).
|
|
|
_allocator->release_mutator_alloc_region();
|
|
|
|
|
|
// This timing is only used by the ergonomics to handle our pause target.
|
|
|
// It is unclear why this should not include the full pause. We will
|
|
|
// investigate this in CR 7178365.
|
|
|
//
|
|
|
// Preserving the old comment here if that helps the investigation:
|
|
|
//
|
|
|
// The elapsed time induced by the start time below deliberately elides
|
|
|
// the possible verification above.
|
|
|
double sample_start_time_sec = os::elapsedTime();
|
|
|
|
|
|
g1_policy()->record_collection_pause_start(sample_start_time_sec);
|
|
|
|
|
|
if (collector_state()->in_initial_mark_gc()) {
|
|
|
concurrent_mark()->pre_initial_mark();
|
|
|
}
|
|
|
|
|
|
g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
|
|
|
|
|
|
evacuation_info.set_collectionset_regions(collection_set()->region_length());
|
|
|
|
|
|
// Make sure the remembered sets are up to date. This needs to be
|
|
|
// done before register_humongous_regions_with_cset(), because the
|
|
|
// remembered sets are used there to choose eager reclaim candidates.
|
|
|
// If the remembered sets are not up to date we might miss some
|
|
|
// entries that need to be handled.
|
|
|
g1_rem_set()->cleanupHRRS();
|
|
|
|
|
|
register_humongous_regions_with_cset();
|
|
|
|
|
|
assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
|
|
|
|
|
|
// We call this after finalize_cset() to
|
|
|
// ensure that the CSet has been finalized.
|
|
|
_cm->verify_no_cset_oops();
|
|
|
|
|
|
if (_hr_printer.is_active()) {
|
|
|
G1PrintCollectionSetClosure cl(&_hr_printer);
|
|
|
_collection_set.iterate(&cl);
|
|
|
}
|
|
|
|
|
|
// Initialize the GC alloc regions.
|
|
|
_allocator->init_gc_alloc_regions(evacuation_info);
|
|
|
|
|
|
G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), collection_set()->young_region_length());
|
|
|
pre_evacuate_collection_set();
|
|
|
|
|
|
// Actually do the work...
|
|
|
evacuate_collection_set(&per_thread_states);
|
|
|
|
|
|
post_evacuate_collection_set(evacuation_info, &per_thread_states);
|
|
|
|
|
|
const size_t* surviving_young_words = per_thread_states.surviving_young_words();
|
|
|
free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
|
|
|
|
|
|
eagerly_reclaim_humongous_regions();
|
|
|
|
|
|
record_obj_copy_mem_stats();
|
|
|
_survivor_evac_stats.adjust_desired_plab_sz();
|
|
|
_old_evac_stats.adjust_desired_plab_sz();
|
|
|
|
|
|
double start = os::elapsedTime();
|
|
|
start_new_collection_set();
|
|
|
g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
|
|
|
|
|
|
if (evacuation_failed()) {
|
|
|
set_used(recalculate_used());
|
|
|
if (_archive_allocator != NULL) {
|
|
|
_archive_allocator->clear_used();
|
|
|
}
|
|
|
for (uint i = 0; i < ParallelGCThreads; i++) {
|
|
|
if (_evacuation_failed_info_array[i].has_failed()) {
|
|
|
_gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
|
|
|
}
|
|
|
}
|
|
|
} else {
|
|
|
// The "used" of the the collection set have already been subtracted
|
|
|
// when they were freed. Add in the bytes evacuated.
|
|
|
increase_used(g1_policy()->bytes_copied_during_gc());
|
|
|
}
|
|
|
|
|
|
if (collector_state()->in_initial_mark_gc()) {
|
|
|
// We have to do this before we notify the CM threads that
|
|
|
// they can start working to make sure that all the
|
|
|
// appropriate initialization is done on the CM object.
|
|
|
concurrent_mark()->post_initial_mark();
|
|
|
// Note that we don't actually trigger the CM thread at
|
|
|
// this point. We do that later when we're sure that
|
|
|
// the current thread has completed its logging output.
|
|
|
}
|
|
|
|
|
|
allocate_dummy_regions();
|
|
|
|
|
|
_allocator->init_mutator_alloc_region();
|
|
|
|
|
|
{
|
|
|
size_t expand_bytes = _heap_sizing_policy->expansion_amount();
|
|
|
if (expand_bytes > 0) {
|
|
|
size_t bytes_before = capacity();
|
|
|
// No need for an ergo logging here,
|
|
|
// expansion_amount() does this when it returns a value > 0.
|
|
|
double expand_ms;
|
|
|
if (!expand(expand_bytes, _workers, &expand_ms)) {
|
|
|
// We failed to expand the heap. Cannot do anything about it.
|
|
|
}
|
|
|
g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
|
|
|
}
|
|
|
}
|
|
|
|
|
|
// We redo the verification but now wrt to the new CSet which
|
|
|
// has just got initialized after the previous CSet was freed.
|
|
|
_cm->verify_no_cset_oops();
|
|
|
|
|
|
// This timing is only used by the ergonomics to handle our pause target.
|
|
|
// It is unclear why this should not include the full pause. We will
|
|
|
// investigate this in CR 7178365.
|
|
|
double sample_end_time_sec = os::elapsedTime();
|
|
|
double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
|
|
|
size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
|
|
|
g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
|
|
|
|
|
|
evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
|
|
|
evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
|
|
|
|
|
|
if (VerifyRememberedSets) {
|
|
|
log_info(gc, verify)("[Verifying RemSets after GC]");
|
|
|
VerifyRegionRemSetClosure v_cl;
|
|
|
heap_region_iterate(&v_cl);
|
|
|
}
|
|
|
|
|
|
_verifier->verify_after_gc(verify_type);
|
|
|
_verifier->check_bitmaps("GC End");
|
|
|
|
|
|
assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
|
|
|
_ref_processor_stw->verify_no_references_recorded();
|
|
|
|
|
|
// CM reference discovery will be re-enabled if necessary.
|
|
|
}
|
|
|
|
|
|
#ifdef TRACESPINNING
|
|
|
ParallelTaskTerminator::print_termination_counts();
|
|
|
#endif
|
|
|
|
|
|
gc_epilogue(false);
|
|
|
}
|
|
|
|
|
|
// Print the remainder of the GC log output.
|
|
|
if (evacuation_failed()) {
|
|
|
log_info(gc)("To-space exhausted");
|
|
|
}
|
|
|
|
|
|
g1_policy()->print_phases();
|
|
|
heap_transition.print();
|
|
|
|
|
|
// It is not yet to safe to tell the concurrent mark to
|
|
|
// start as we have some optional output below. We don't want the
|
|
|
// output from the concurrent mark thread interfering with this
|
|
|
// logging output either.
|
|
|
|
|
|
_hrm.verify_optional();
|
|
|
_verifier->verify_region_sets_optional();
|
|
|
|
|
|
TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
|
|
|
TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
|
|
|
|
|
|
print_heap_after_gc();
|
|
|
print_heap_regions();
|
|
|
trace_heap_after_gc(_gc_tracer_stw);
|
|
|
|
|
|
// We must call G1MonitoringSupport::update_sizes() in the same scoping level
|
|
|
// as an active TraceMemoryManagerStats object (i.e. before the destructor for the
|
|
|
// TraceMemoryManagerStats is called) so that the G1 memory pools are updated
|
|
|
// before any GC notifications are raised.
|
|
|
g1mm()->update_sizes();
|
|
|
|
|
|
_gc_tracer_stw->report_evacuation_info(&evacuation_info);
|
|
|
_gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
|
|
|
_gc_timer_stw->register_gc_end();
|
|
|
_gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
|
|
|
}
|
|
|
// It should now be safe to tell the concurrent mark thread to start
|
|
|
// without its logging output interfering with the logging output
|
|
|
// that came from the pause.
|
|
|
|
|
|
if (should_start_conc_mark) {
|
|
|
// CAUTION: after the doConcurrentMark() call below,
|
|
|
// the concurrent marking thread(s) could be running
|
|
|
// concurrently with us. Make sure that anything after
|
|
|
// this point does not assume that we are the only GC thread
|
|
|
// running. Note: of course, the actual marking work will
|
|
|
// not start until the safepoint itself is released in
|
|
|
// SuspendibleThreadSet::desynchronize().
|
|
|
do_concurrent_mark();
|
|
|
}
|
|
|
|
|
|
return true;
|
|
|
}<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>
|
|
|
<p>往下走就是这一步<code>G1Policy::finalize_collection_set</code>,去处理新生代和老年代</p>
|
|
|
<pre class="line-numbers language-C++" data-language="C++"><code class="language-C++">void G1Policy::finalize_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) {
|
|
|
double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms, survivor);
|
|
|
_collection_set->finalize_old_part(time_remaining_ms);
|
|
|
}<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span></span></code></pre>
|
|
|
<p>这里分别调用了两个方法,可以看到剩余时间是往下传的,来看一下具体的方法</p>
|
|
|
<pre class="line-numbers language-C++" data-language="C++"><code class="language-C++">double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors) {
|
|
|
double young_start_time_sec = os::elapsedTime();
|
|
|
|
|
|
finalize_incremental_building();
|
|
|
|
|
|
guarantee(target_pause_time_ms > 0.0,
|
|
|
"target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
|
|
|
|
|
|
size_t pending_cards = _policy->pending_cards();
|
|
|
double base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards);
|
|
|
double time_remaining_ms = MAX2(target_pause_time_ms - base_time_ms, 0.0);
|
|
|
|
|
|
log_trace(gc, ergo, cset)("Start choosing CSet. pending cards: " SIZE_FORMAT " predicted base time: %1.2fms remaining time: %1.2fms target pause time: %1.2fms",
|
|
|
pending_cards, base_time_ms, time_remaining_ms, target_pause_time_ms);
|
|
|
|
|
|
// The young list is laid with the survivor regions from the previous
|
|
|
// pause are appended to the RHS of the young list, i.e.
|
|
|
// [Newly Young Regions ++ Survivors from last pause].
|
|
|
|
|
|
uint survivor_region_length = survivors->length();
|
|
|
uint eden_region_length = _g1h->eden_regions_count();
|
|
|
init_region_lengths(eden_region_length, survivor_region_length);
|
|
|
|
|
|
verify_young_cset_indices();
|
|
|
|
|
|
// Clear the fields that point to the survivor list - they are all young now.
|
|
|
survivors->convert_to_eden();
|
|
|
|
|
|
_bytes_used_before = _inc_bytes_used_before;
|
|
|
time_remaining_ms = MAX2(time_remaining_ms - _inc_predicted_elapsed_time_ms, 0.0);
|
|
|
|
|
|
log_trace(gc, ergo, cset)("Add young regions to CSet. eden: %u regions, survivors: %u regions, predicted young region time: %1.2fms, target pause time: %1.2fms",
|
|
|
eden_region_length, survivor_region_length, _inc_predicted_elapsed_time_ms, target_pause_time_ms);
|
|
|
|
|
|
// The number of recorded young regions is the incremental
|
|
|
// collection set's current size
|
|
|
set_recorded_rs_lengths(_inc_recorded_rs_lengths);
|
|
|
|
|
|
double young_end_time_sec = os::elapsedTime();
|
|
|
phase_times()->record_young_cset_choice_time_ms((young_end_time_sec - young_start_time_sec) * 1000.0);
|
|
|
|
|
|
return time_remaining_ms;
|
|
|
}<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>
|
|
|
<p>下面是老年代的部分</p>
|
|
|
<pre class="line-numbers language-C++" data-language="C++"><code class="language-C++">void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
|
|
|
double non_young_start_time_sec = os::elapsedTime();
|
|
|
double predicted_old_time_ms = 0.0;
|
|
|
|
|
|
if (collector_state()->in_mixed_phase()) {
|
|
|
cset_chooser()->verify();
|
|
|
const uint min_old_cset_length = _policy->calc_min_old_cset_length();
|
|
|
const uint max_old_cset_length = _policy->calc_max_old_cset_length();
|
|
|
|
|
|
uint expensive_region_num = 0;
|
|
|
bool check_time_remaining = _policy->adaptive_young_list_length();
|
|
|
|
|
|
HeapRegion* hr = cset_chooser()->peek();
|
|
|
while (hr != NULL) {
|
|
|
if (old_region_length() >= max_old_cset_length) {
|
|
|
// Added maximum number of old regions to the CSet.
|
|
|
log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached max). old %u regions, max %u regions",
|
|
|
old_region_length(), max_old_cset_length);
|
|
|
break;
|
|
|
}
|
|
|
|
|
|
// Stop adding regions if the remaining reclaimable space is
|
|
|
// not above G1HeapWastePercent.
|
|
|
size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
|
|
|
double reclaimable_percent = _policy->reclaimable_bytes_percent(reclaimable_bytes);
|
|
|
double threshold = (double) G1HeapWastePercent;
|
|
|
if (reclaimable_percent <= threshold) {
|
|
|
// We've added enough old regions that the amount of uncollected
|
|
|
// reclaimable space is at or below the waste threshold. Stop
|
|
|
// adding old regions to the CSet.
|
|
|
log_debug(gc, ergo, cset)("Finish adding old regions to CSet (reclaimable percentage not over threshold). "
|
|
|
"old %u regions, max %u regions, reclaimable: " SIZE_FORMAT "B (%1.2f%%) threshold: " UINTX_FORMAT "%%",
|
|
|
old_region_length(), max_old_cset_length, reclaimable_bytes, reclaimable_percent, G1HeapWastePercent);
|
|
|
break;
|
|
|
}
|
|
|
|
|
|
double predicted_time_ms = predict_region_elapsed_time_ms(hr);
|
|
|
if (check_time_remaining) {
|
|
|
if (predicted_time_ms > time_remaining_ms) {
|
|
|
// Too expensive for the current CSet.
|
|
|
|
|
|
if (old_region_length() >= min_old_cset_length) {
|
|
|
// We have added the minimum number of old regions to the CSet,
|
|
|
// we are done with this CSet.
|
|
|
log_debug(gc, ergo, cset)("Finish adding old regions to CSet (predicted time is too high). "
|
|
|
"predicted time: %1.2fms, remaining time: %1.2fms old %u regions, min %u regions",
|
|
|
predicted_time_ms, time_remaining_ms, old_region_length(), min_old_cset_length);
|
|
|
break;
|
|
|
}
|
|
|
|
|
|
// We'll add it anyway given that we haven't reached the
|
|
|
// minimum number of old regions.
|
|
|
expensive_region_num += 1;
|
|
|
}
|
|
|
} else {
|
|
|
if (old_region_length() >= min_old_cset_length) {
|
|
|
// In the non-auto-tuning case, we'll finish adding regions
|
|
|
// to the CSet if we reach the minimum.
|
|
|
|
|
|
log_debug(gc, ergo, cset)("Finish adding old regions to CSet (old CSet region num reached min). old %u regions, min %u regions",
|
|
|
old_region_length(), min_old_cset_length);
|
|
|
break;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
// We will add this region to the CSet.
|
|
|
time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0);
|
|
|
predicted_old_time_ms += predicted_time_ms;
|
|
|
cset_chooser()->pop(); // already have region via peek()
|
|
|
_g1h->old_set_remove(hr);
|
|
|
add_old_region(hr);
|
|
|
|
|
|
hr = cset_chooser()->peek();
|
|
|
}
|
|
|
if (hr == NULL) {
|
|
|
log_debug(gc, ergo, cset)("Finish adding old regions to CSet (candidate old regions not available)");
|
|
|
}
|
|
|
|
|
|
if (expensive_region_num > 0) {
|
|
|
// We print the information once here at the end, predicated on
|
|
|
// whether we added any apparently expensive regions or not, to
|
|
|
// avoid generating output per region.
|
|
|
log_debug(gc, ergo, cset)("Added expensive regions to CSet (old CSet region num not reached min)."
|
|
|
"old: %u regions, expensive: %u regions, min: %u regions, remaining time: %1.2fms",
|
|
|
old_region_length(), expensive_region_num, min_old_cset_length, time_remaining_ms);
|
|
|
}
|
|
|
|
|
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cset_chooser()->verify();
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}
|
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stop_incremental_building();
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log_debug(gc, ergo, cset)("Finish choosing CSet. old: %u regions, predicted old region time: %1.2fms, time remaining: %1.2f",
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old_region_length(), predicted_old_time_ms, time_remaining_ms);
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double non_young_end_time_sec = os::elapsedTime();
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phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
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QuickSort::sort(_collection_set_regions, _collection_set_cur_length, compare_region_idx, true);
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}<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>
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<p>上面第三行是个判断,当前是否是 mixed 回收阶段,如果不是的话其实是没有老年代什么事的,所以可以看到代码基本是从这个 if 判断<br><code>if (collector_state()->in_mixed_phase()) {</code>开始往下走的<br>先写到这,偏向于做笔记用,有错轻拍</p>
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