前面几篇中，我们谈论了synchronized、final以及voilate的用法和底层实现，都绕不开一个话题-Java内存模型（java memory model，简称JMM）。Java内存模型是保证线程安全的基础，主要描述了程序中全序的同步动作在不同线程访问共享全局变量时所体现的原子性、可见性和有序性上的限制。1、定义维基百科定义：The Java memory model describes how threads in the Java programming language interact through memory. Together with ...
Understanding Java Memory Management - IBMJava Native Interface (JNI) Objects and CodeJava Native Interface code can directly allocate native memory using system calls:– malloc, calloc, realloc etc.Uses memory from the memory from the process address space– Just like the Java heap doesSome Java Class Library code uses JNI, and therefore allocates native memory– java.lang.Class– java.lang.Threa...
如图所示：频繁出现此种情况，项目太大，导致内存溢出，排除代码问题外，可参照以下方式解决方法一：增大内存，可以解决亲测全局安装increase-memory-limit
npm install -g increase-memory-limit
进入工程目录，执行：
increase-memory-limitOK，解决完毕！方法二：删除 .cnpmr在执行npm -v命令时，报如下错误：FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory解决方...
How to Use DTrace to Troubleshoot Java Native Memory Problems on Oracle Solaris 11Hands-On Labs of the System Admin and Developer Community of OTNby Wang Yu, Vincent Liu, and Gary WangThis lab will introduce the basic concepts of DTrace and provide exercises for using DTrace to identify common Java native memory problems, such as direct buffer overflow, Inflater/Deflater memory leak, and thread st...
ByteBuffer的源码中有这样一段注释：A byte buffer is either direct or non-direct. Given a direct byte buffer, the Java virtual machine will make a best effort to perform native I/O operations directly upon it. That is, it will attempt to avoid copying the buffers content to (or from) an intermediate buffer before (or after) each invocation of one of the underlying operating systems native I/O operat...
Q：第一次提交wordcount案例，OK，一切正常。再次提交，出现下述错误。完整错误粘贴如下：
21/01/27 14:55:48 INFO spark.SecurityManager: Changing modify acls groups to:
21/01/27 14:55:48 INFO spark.SecurityManager: SecurityManager: authentication disabled; ui acls disabled; users with view permissions: Set(hadoop); groups with view permissions: Set(); users with modify permissions: Set(hadoop); group...
典型特性
（1）NMT功能默认关闭
（2）借助jcmd工具可以获取摘要/详细报告
（3）建立基线并比较其变换量
（4）在进程退出时打印内存报告
1.开启方法
启动目录中添加如下参数，默认为off，可以设置为summary或detail来打印概要或详细信息。
-XX:NativeMemoryTracking=[off | summary | detail]
注意：打开NMT会增加5%-10%的性能开销。
2.Jcmd工具获取NMT信息jcmd <pid> VM.native_memory [summary | detail | baseline | summary.d...
问题描述：
Idea编译本地java项目提示：系统资源部不足，java:OutOfMemoryError:insufficient memory
原因分析：idea编译进程堆尺寸太小，增大尺寸即可解决方案：
idea设置：file---->settings---->Build,Exception,Deployment---->Compiler,将build process heap size 增大即可，我原先是700，增大了一倍就可以正常编译了
ERROR spark.SparkContext: Error initializing SparkContext.
java.lang.IllegalArgumentException: Required executor memory (1024), overhead (384 MB), and PySpark memory (0 MB) is above the max threshold (1024 MB) of this cluster! Please check the values of yarn.scheduler.maximum-allocation-mb and/or yarn.nodemanager.resource.memory-mb.
at org.apache.spark.deploy.yarn.Client.verifyClusterResources(Cli...
我们在Windows上使用JBoss_4_0_4_GA和JDK 1.5.0(无更新)
JBoss服务器在Wrapper(版本3.2.3)http://wrapper.tanukisoftware.org中运行.
由于JVM太老了,我甚至无法在JVM上使用-XX：HeapDumpOnOutOfMemoryError选项.
找出问题有什么选择？
像往常一样,Out of Memory异常发生在应用程序的不同部分.
我没有权利立即升级JVM.The current VM settingsJava Additional Parameterswrapper.java.additional.1=-Xms512mwrapper.java.additional...
我使用了Out Of Memory help from sun’s site.它被引用为Out Of Memory : Requested array size exceeds VM limit
This indicates that the application attempted to allocate an array that is larger than the heap size. Forexample, if an application tries to allocate an array of 512MB but the maximum heap size is 256MB,then this error will be thrown. In most cases the problem is likely to be either that the...
我存储了1.11亿个键值对(一个键可以有多个值 – 最大值为2/3),其键为50位整数,值为32位(最大值)整数.现在,我的要求是：Fast Insertion of (Key, Value) pair [allowing duplicates]
Fast retrieving of value/values based on key.一个很好的解决方案是基于MultiMap给出here.但是,我想在主内存中存储更多的键值对,没有/小的性能损失.我从网络文章中研究过B Tree,R Tree,B Tree,Compact Multimap等可以很好地解决这个问题.有谁能够帮...
我应该如何从内存中清理TableView实例,
从我学到的,
>删除附加到表的所有侦听器. (它是否适用于相应表的列和行？)>清除所有列.和>没有对表实例的强引用.
从外部参考我做了以下,
>将焦点模型设置为null.>设置鼠标,键侦听器为null.> setSelectionModel为null.> setItems为空的ObservableArraylist.
最后,我的代码如下所示.//I gave a try for, RowFactory and ColumnFactory to null. tableView.setRowFactory(null);for (TableCo...
我正在使用Lucene v4.10.4.我有相当大的索引,它可能超过几GB.所以我在初始化IndexSearcher时得到OutOfMemoryError：try (Directory dir = FSDirectory.open(new File(indexPath))) { //Out of Memory here!IndexSearcher searcher = new IndexSearcher(DirectoryReader.open(indexDir));如何告诉Lucene的DirectoryReader不能一次加载到256 MB以上的内存？
日志Caused by: java.lang.OutOfMemoryError: Java heap spaceat org.apach...
在给出错误tomcat退出(关闭)之后,我的tomcat中的一个我的应用程序被部署的连续内存错误.
我拿了日志文件,发现了这个SEVERE: Error allocating socket processor
java.lang.OutOfMemoryError: unable to create new native threadat java.lang.Thread.start0(Native Method)at java.lang.Thread.start(Thread.java:597)at org.apache.tomcat.util.net.JIoEndpoint$Worker.start(JIoEndpoint.java:513)at org.apache.tomcat.util.net...