Java native memory. native_memory summary.

Java native memory ZipInputStream using the first one. You can access NMT data by using the jcmd utility. 一般情况怎么管理原生内存(native memory)? 在Java 9之前, 最直接, 最简单的方法就是用finalize(). Native heap means you use native memory by means of Native memory is the memory used by the JVM as it runs on the OS. The next table taken from Oracle’s Java服务出现了OOM(Out Of Memory)问题，总结了一些相对通用的方案，希望能帮助到Java技术栈的同学。某Java服务(假设PID=10765)出现了OOM，最常见的原因为：有可能是内存分配确实过小，而正常业务使用了大量内存某一个对象被频繁申请，却没有释放，内存不断泄漏，导致内存耗尽某一个资源被频繁申请 Adding up the "capacity" items from jps shows that only my 6144m is being used for java heap. # Native memory allocation (mmap) failed to map 65536 bytes for committing reserved memory. 首先，你要在Java启动项中，加入启动项： -XX:NativeMemoryTracking=detail 然后，重新启动Java程序。执行如下命令： jcmd 14179 VM. For details about NMT scope, how to enable NMT, and other additional usage details, see Native Memory Tracking. bash-3. Native memory consists of several native memory categories, such as: java heap, metaspace, thread etc. Direct memory means you use native memory by means of java. Let’s create a native memory segment of 200 bytes: MemorySegment memorySegment =Arena. For example, on a machine with 4GB of RAM, the maximum Java heap size will be set to 1GB. Note: Static Methods and Variables were previous stored in Class Area (Till Java 8). 摘要：本篇将介绍NMT追踪区域的部分内存类型——Java heap、 Class 、 Thread 、 Code 以及 GC 。 本文分享自华为云社区《Native Memory Tracking 详解（2）:追踪区域分析(一)》，作者：毕昇小助手。 本篇将介绍NMT追踪区域的部分内存类型——Java heap、Class、Thread、Code 以及 GC。 1. Utilize Java's synchronized blocks or consider Java's ReentrantLock for more complex scenarios Context When Java 17 was released in September we (the platform team at Auto Trader) were fairly quick to provide a new Docker base image to allow our developers to gain the benefits of the new goodness in the JDK available since Java 11, the previous LTS version. OSが管理するメモリ領域. Where the heck is the rest of the memory being used? Stack memory? Native heap? I'm not even sure how to proceed. relying on platform specific support like the debug support provided by the Microsoft Visual C++ compiler 为什么我的 JVM 会被 OOMKiller 等等，这都涉及到 JAVA 虚拟机对内存的一个使用情况，不如让我们来一探其中究竟。 从 OpenJDK8 起有了一个很 nice 的虚拟机内部功能：Native Memory Tracking (NMT) 。我们可以使用 NMT 来追踪了解 JVM 的内存使用详情（即上图中的 JVM Memory top PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 27420 douyiwa+ 20 0 10. Juraj この章では、ネイティブ・メモリー・トラッキング(NMT)機能について説明します。NMTは、HotSpot VMの内部メモリー使用状況を追跡するJava HotSpot VM機能です。NMTデータは、jcmdユーティリティを使用してアクセスできます。NMTは、サードパーティ・ネイティブ・コードおよびOracle Java Development Kit (JDK Java applications often use native memory for various operations, such as interacting with the operating system, allocating memory for native code, and storing data in device buffers. max_map_count sysctl parameter (which defaults to 65536). Possible reasons: The system is out of physical RAM or swap space; In 32 bit mode, the process size limit was hit; Possible solutions: Reduce memory load on the system Native Allocations 通常，heap是java程序占用内存中的最大的一部分，但也有特例。除了heap，JVM会分配很大一块内存，用于存储metadata、application code、the code generated by JIT、internal data structures等等。 Native Memory Tracking (NMT) 我们知道了JVM中消耗内存的几个源头，现在就 OpenJDK 64-Bit Server VM warning: INFO: os::commit_memory(0x0000ffff7cab0000, 65536, 1) failed; error='Cannot allocate memory' (errno=12) # # There is insufficient memory for the Java Runtime Environment to continue. This will break down a JVM's memory consumption by category, which helps explain how other memory categories beyond Heap contribute to a JVM's memory consumption. NMT doesn't give complete information for the memory used by the class data sharing (CDS) archive. NMT in this release does not track third party native code memory allocations and JDK class libraries. 文章浏览阅读607次。本文详细介绍了Java的Native Memory Tracking（NMT），用于追踪和分析本地内存使用。通过启用NMT并在应用程序中使用，可以获取本地内存分配、释放等信息，并利用jcmd工具进行分析。文章还提供了一个简单的Java示例，展示了NMT的实际运用，强调了NMT在性能优化和内存管理中的价值 知乎，中文互联网高质量的问答社区和创作者聚集的原创内容平台，于 2011 年 1 月正式上线，以「让人们更好的分享知识、经验和见解，找到自己的解答」为品牌使命。知乎凭借认真、专业、友善的社区氛围、独特的产品机制以及结构化和易获得的优质内容，聚集了中文互联网科技、商业、 整个memory主要包含了Java Heap、Class、Thread、Code、GC、Compiler、Internal、Other、Symbol、Native Memory Tracking、Arena Chunk这几部分；其中reserved表示应用可用的内存大小，committed表示应用正在使用的内存大小 本文主要研究一下HotSpot VM的Native Memory Tracking. Inflater and its native method java. DirectByteBuffer. lang. To track down leaks, use jemalloc and turn on sampling profiling using Native memory allocation failures are much harder to handle than allocation failures on the java heap. native_memory summary. 0 0. Java 7 has This guy successfully used jemalloc to detect his cause of a Java native memory leak and I gave it a try. Follow answered Jun 21, 2022 at 5:07. Javaプログラムが実行されると、Javaのプロ This chapter describes the Native Memory Tracking (NMT) feature. NMT does not include NMT MBean in HotSpot for The Non-Heap memory (AKA Native Memory/Off-heap memory) is comprised of several areas: Metaspace; Thread Memory (Stack Memory) Code Cache; Garbage Collector Data; The Metaspace. The PermGen’s 对于我们这些 Java 开发以及 JVM 使用者而言（对于抄袭狗是没有好果汁吃的），我们只关心并且查看 Native Memory Tracking 的 summary 信息即可，detail 信息一般是供 JVM 开发人员使用的，我们不用太关心，我们后面的分析也只会涉及 Native Memory Tracking 的 summary 部分。 We finally found the underlying Java native memory leak a few weeks ago. Native memory allocation (mmap) failed to map一台服务器上部署很多JAVA进程已经是微服务的常态，但也有些坑。背景，测试服务器上的一些JAVA进程突然挂掉，查看call back的日志发现如下：# There is insufficient memory for the Java Runtime Environment to JVM管理的内存可以总体划分为两部分：Heap Memory和Native Memory。前者我们比较熟悉，是供Java应用程序使用的；后者也称为C-Heap，是供JVM自身进程使用的。Heap Memory及其内部各组成的大小可以通过JVM的一系列命令行参数来控制，在此不赘述。Native Memory没有相应的参数来控制大小，其大小依赖于操作系统 . These two heaps have different purposes and are maintained by different mechanisms. Feature. Native memory allocation (malloc) failed to allocate xxxxx bytes for committing reserved memory. native_memory detail查看到的内存分布如下： Class Interfaces: Memory for class interfaces is also allocated here. The Native Memory Tracking (NMT) is a Java Hotspot VM feature that tracks internal memory usage for a HotSpot JVM. When we think about memory leaks in Java, we usually do it for Java heap memory leak which is used to store objects and are if they are not garbage collected ever. 除了方法区域外，Java 虚拟机实现可能需要内存用于内部的处理或优化。例如，JIT 编译器需要内存来存储从 Java 虚拟机代码转换的本机代码（储存在 CodeCache 中），以获得高性能。 从 OpenJDK8 起有了一个很 nice 的虚拟机内部功能： Native Memory Tracking (NMT) 。 I was facing similar issue with one of our Apache Spark job where we were submitting our application as a fat jar, After analyzing thread dumps we figured that Hibernate is the culprit, we used to load hibernate classes on startup of the application which was actually using java. zip. JavaではJVMがその役割を担っています。メモリの使用や解放を自動で行ってくれるため、ユーザがメモリを意識せずにコーディングできるというわけです。 メモリの種類. The examples in this chapter demonstrate how to allocate and access native segments. This feature is not enabled by default, and Native Memory没有相应的参数来控制大小，其大小依赖于操作系统进程的最大值（对于32位系统就是3~4G，各种系统的实现并不一样），以及生成的Java字节码大小、创建的线程数量、维持java对象的状态信息大小（用于GC）以及一些第三方的包，比如JDBC驱动使用 对于我们这些 Java 开发以及 JVM 使用者而言（对于抄袭狗是没有好果汁吃的），我们只关心并且查看 Native Memory Tracking 的 summary 信息即可，detail 信息一般是供 JVM 开发人员使用的，我们不用太关心，我们后面的分析也只会涉及 Native Memory Tracking 的 summary 部分。 由于直接内存在Java堆外，因此它的大小不会直接受限于一Xmx指定的最大 堆大小，但是系统内存是有限的，Java堆和直接内存的总和依然受限于操作系统能给出的最大内存。访问直接内存的速度会优于Java堆。3. diff 39057: Native Memory Tracking: Total: reserved=5761678KB +52943KB, committed=472350KB +104143KB - Java Heap (reserved=4194304KB, committed JVM native memory leak is suspected, so I want to track memory. TL;DR: Always close GZIPInputStream and GZIPOutputStream since they use native memory via zlib. nio. When you use Native Memory Tracking with jcmd, you can track Java Virtual Machine (JVM) or HotSpot VM memory usage at different levels. Over the course of a few years we’ve standardised the way the JVM is configured out of the box for Javaのメモリ構成. native_memory detail. 6k次。JVM管理的内存分为Heap Memory和Native Memory，前者供Java应用使用，后者供JVM自身进程使用。介绍了Native Memory存储内容，如管理状态数据、用于JNI调用等。还提到DirectBuffer的好处及回收时机，最后分析了Native Memory溢出的原因。 Cause: Java class metadata (the virtual machine's internal presentation of a Java class) is allocated in native memory (referred to here as Metaspace). If left to continue growing, it will consume all memory on the system and we will eventually see the system freeze up throwing swap space A memory segment backed by native memory is known as a native memory segment. In Linux, the maximum per-process number of map areas is controlled by vm. By enabling NMT, you can collect detailed reports on how much native memory is allocated, used, and freed by your application and the libraries it depends on. The objective of this blog post is to discuss native 文章浏览阅读9. 这几个都是JVM内存相关概念，之前一直有点模糊， 最近查了一些资料，在此记录。 1 Heap Memory. Javaアプリケーションを利用している場合、最近ではContainerを利用してアプリケーションを起動しているところも多いかと思います。 # jcmd <PROCESS_ID> VM. Understanding how and when this memory is used is paramount for optimizing performance and resource management. 2$ jcmd 39057 VM. Native Memory Tracking (NMT) is an analysis tool which allows you to investigate internal memory usage of Java applications in Azul Zing Builds of OpenJDK (Zing). . Inflater. Thread. The JVM generates native code for a number of reasons, including the dynamically generated interpreter loop, Java Native Interface (JNI) stubs, and Java --enable-monitoring=nmt を指定してビルドされた Native Image は NMT 機能を使用できる様になります。 ただし現時点（GraalVM for JDK 23）の Native Image の NMT は OpenJDK のそれと違い、jcmd を使用してアプリケーション実行中の特定のタイミングの NMT 情報を取得したり、ベースラインを設定できません。 为什么我的 JVM 会被 OOMKiller 等等，这都涉及到 JAVA 虚拟机对内存的一个使 从 OpenJDK8 起有了一个很 nice 的虚拟机内部功能：Native Memory Tracking (NMT) 。我们可以使用 NMT 来追踪了解 JVM 的内存使用详情（即上图中的 JVM Memory 部分），帮助我们排查内存增长与内存 本地内存（Native memory），也称为C-Heap，是供JVM自身进程使用的。当Java Heap空间不足时会触发GC，但Native memory空间不够却不会触发GC。 元空间存在于本地内存，意味着只要本地内存足够，它不会出现像永久代中“java. Key Features This chapter describes the Native Memory Tracking (NMT) feature. NMT is a Java Hotspot VM feature that tracks internal memory usage for a HotSpot VM. State: RUNNABLE at sun. Java Native Memory Tracking is a feature introduced in JDK 8 that allows you to see the memory consumption of native code linked with your Java application. java2d. I’ll discuss this C code, where it is The JVM maintains two memory areas, the Java™ heap, and the native (or system) heap. If the same image is executed on a machine that has 32GB of RAM, the maximum Java heap size will be set to 知乎，中文互联网高质量的问答社区和创作者聚集的原创内容平台，于 2011 年 1 月正式上线，以「让人们更好的分享知识、经验和见解，找到自己的解答」为品牌使命。知乎凭借认真、专业、友善的社区氛围、独特的产品机制以及结构化和易获得的优质内容，聚集了中文互联网科技、商业、 # Native memory allocation (mmap) failed to map 746061824 bytes for committing reserved memory. A Java application uses four key areas: the Stack, Heap, Method Area (Metaspace), and Native Memory. NMT is meant to be a temporary monitoring tool which allows you to monitor and diagnose memory-related issues within the JVM as it helps you to understand how the JVM allocates memory 我正在尝试使用命令java -version启动一个新的jvm，但它报告了一个错误： # There is insufficient memory for the Java Runtime Environment to continue. kcms. These include: wrapping all memory allocation and deallocation calls to track the amount of memory used. Also, this release does not include NMT MBean in HotSpot for JMC. This C code is called by native methods in certain Java classes. You can access NMT data using jcmd utility. diff <PROCESS_ID>: Native memory is memory allocated by the OS on behalf of the Java process through C code. 6w次，点赞14次，收藏23次。JVM管理的内存可以总体划分为两部分：Heap Memory和Native Memory。前者我们比较熟悉，是供Java应用程序使用的；后者也称为C-Heap，是供JVM自身进程使用的。Heap Memory及其内部各组成的大小可以通过JVM的一系列命令行参数来控制，在此不赘述。 验证后发现问题和JDK8的bug非常类似，测试后也证实确实如此，最后通过升级JDK解决了这个问题。 导致这个问题的组件是Jackson Streaming API 中的 JsonFactory. init(boolean),; class java. . 直接内存不是虚拟机运行时数据区的一 文章浏览阅读1. 7g 697560 17596 S 100. If the same image is executed on a machine that has 32GB of RAM, the maximum Java heap size will be set to Many native libraries, especially older C libraries, may not handle concurrent access effectively, leading to race conditions or corrupted data. NMT does not track memory allocations for third To circumvent this, we could try making more room available for native allocations by reducing the size of Java heap, Metaspace, number of threads and their stack sizes, and even terminating other processes on the In this blog, I’m going to discuss native memory tracking (NMT), which we can use to isolate any abnormal memory growing up at the VM level. Each has a distinct purpose to ensure efficient memory management, multitasking, and the ability There is insufficient memory for the Java Runtime Environment to continue. Share. NMT does not track memory allocations for third-party native code and Oracle Java Development Kit (JDK) class libraries. Arrays: Since arrays are considered objects in Java, their memory is allocated in the heap as well. 구체적인 사용법 등 자세한 내용은 Java NIO Direct Buffer를 이용해서 대용량 파일 행 기준으로 쪼개기를 참고하고 장단점만 요약하면 다음과 같다. 导读：Java8给 HotSpot VM引入了Native Memory Tracking (便于阅读我统一简称为NMT)特性，可以用于追踪JVM的内部内存使用，并可以通过jcmd命令来访问。 整个memory主要包含了Java Heap、Class、Thread、Code、GC、Compiler、Internal、Other、Symbol、Native Memory Tracking、Arena Chunk这几部分 Native Memory Tracking (NMT) is a mechanism provided by the JVM (Java Virtual Machine) that allows developers to monitor and track memory usage, particularly for native code allocations. 简单理解： java process memory = java heap + native memory。1. 使用Java层面的工具定位内存区域（堆内内存、Code区域或者使用unsafe. # Possible reasons: # The system is out of physical RAM or swap space # In 32 bit mode, the process size limit was hit # Decrease number of Java threads # Decrease Java thread stack sizes (-Xss) # Set larger code cache with -XX:ReservedCodeCacheSize 对于我们这些 Java 开发以及 JVM 使用者而言（对于抄袭狗是没有好果汁吃的），我们只关心并且查看 Native Memory Tracking 的 summary 信息即可，detail 信息一般是供 JVM 开发人员使用的，我们不用太关心，我们后面的分析也只会涉及 Native Memory Tracking 的 summary 部分。 The Troubleshooting guide for Java SE 6 with Hotspot VM contains a fairly elaborate section on techniques to aid in detecting native memory leaks. 자바에서도 DirectBuffer를 이용해서 JVM Heap이 아닌 Native 메모리를 사용하고 DMA(Direct Memory Access)의 장점을 활용할 수 있다. 关闭 NMT jcmd 1 VM. inflateBytes to read hibernate class files , this was overshooting our If no maximum Java heap size is specified, a native image that uses the G1 GC will set its maximum Java heap size to 25% of the physical memory size. So, i would try, for example, to double it and examine Heap spaces are used for allocating Java objects whereas native memory is the memory available to the OS. Solution: If you need to access native libraries from multiple threads, ensure proper synchronization. native_memory detail 你会在标准输出得到类似下面的内容（本文去掉了许多与本文无关或者重复的信息）： 本文分享自华为云社区《Native Memory Tracking 详解（1）:基础介绍》，作者：毕昇小助手。 0. Testing native heap memory leaks caused by: class java. util. 引言 我们经常会好奇，我启动了一个 JVM，他到底会 为什么我的 JVM 会被 OOMKiller 等等，这都涉及到 JAVA 虚拟机对内存的一个使用情况，不如让我们来一探其中究竟。 JVM 内存究竟包括哪些，可能网上众说纷纭。我们这里由官方提供的一个查看 JVM 内存占用的工具引入，即 Native Memory Tracking。不过要注意的一点是，这个只能监控 JVM 原生申请的内存大小，如果是通过 JDK 封装的系统 API 申请的内存，是统计不到的，例如 Java JDK The Native Memory Tracking (NMT) is a Java HotSpot VM feature that tracks internal memory usage for a Java HotSpot VM. OutOfMemoryError: PermGen space”这种错误。 When you use Native Memory Tracking with jcmd, you can track Java Virtual Machine (JVM) or HotSpot VM memory usage at different levels. 3 0:18. 79 java Native Memory Tracking: Total: reserved=2813077KB, Native Memory Tracking（NMT）是一项强大的功能，可以帮助开发人员在 Java 应用程序中追踪和分析本地内存的使用情况。 NMT 提供了详细的信息，包括本地堆上的分配、释放和使用情况，以及本地内存的不同区域的详细统计信息。 To address this, it is possible to use Java's Native Memory Tracking functionality in order to track a JVM's internal memory usage. 기본적으로 Java Is Java native memory faster (I think this entails ByteBuffer objects?) than traditional heap memory when there are no serialization issues (for instance if I am comparing it with a huge byte[])? Or do the vagaries of garbage collection, etc. Improve this answer. Native segment: This is a memory segment backed by a region of memory outside the Java heap, an off-heap region. But, in current versions of Java static variables and methods are stored in Heap Memory. There are tools and techniques for investigating issues with Java memory consumption: Native Memory Tracking, pmap, jemalloc, async-profiler. But sometimes it's necessary to use a workaround for Java Native Memory Tracking DMA. It provides insight into how memory is being utilized by both Java and native libraries, which is crucial for optimizing Java applications and diagnosing This low-overhead event recording engine built into the JVM is invaluable for observing the runtime characteristics of Java applications and identifying any potential performance issues. cmmGetTransform(Native Method) at These kinds of errors can not only occur because the total amount of heap space is exhausted, but also when the number of memory-mapped areas is exhausted. By leveraging NMT, developers can optimize their applications and prevent NMT is a Java Hotspot VM feature that tracks internal memory usage for a HotSpot VM. cmm. ; Remember: proper way to avoid memory leaks is deallocating memory by calling methods Inflater#end() or ZipInputStream#close(). There's a fairly good chance the application will crash but depending on how critical it is to the system to keep the process size down that might still suit you. CMM. Native Memory Tracking (NMT) is an extremely light There are two kinds of memory segments: Heap segment: This is a memory segment backed by a region of memory inside the Java heap, an on-heap region. This includes the memory it uses for the Java heap space, so Java heap memory is just a JVM-managed Java memory management is a fundamental concept that involves the automatic allocation and deallocation of objects, managed by the Java The JVM maintains two memory areas, the Java™ heap, and the native (or system) heap. 전편에서 Java가 관리하는 영역 이외에 성능 향상을 위해 Native Memory를 사용하는 어플리케이션이 많이 있으니, 메모리 할당시 주의해야 한다고 언급한 적이 있을 것이다. The Java Native Memory Tracking is a powerful tool providing deep insights into memory usage patterns in Java applications. There is a key difference between Java 7 and 8 in the memory management model. Native memory is an Process Area where the JNI codes gets loaded or JVM Libraries gets loaded or the native Performance packs and the Proxy Modules gets loaded. (Lession leared: don’t just clone master branch from github and assume it’s production This memory is used for heap storage and other purposes. そもそもJavaのメモリ管理がどうなっているんだっけ？の概要。 Java7(の途中)まではPermanet領域があったけど、Java8以降はMetaspaceに変更になっている。 Native Memory. JFR continues to become better and better with every new release, with one recent addition being support for native memory tracking (NMT). Here was the Java stack I found that made the transition from Java land, into native code where the memory was collecting: "Thread-539618" #539764 daemon prio=5 os_prio=0 tid=0x00007f6585b31000 nid=0x92fd runnable [0x00007f6b6f9f7000] java. NMT does not include NMT MBean in HotSpot for CodeCache: Contains native code generated by the JVM. JVM管理的堆内存，用来存放Java对象，由GC负责清理。 2 Native Memory/Off-heap Memory Also read: The 7 most important JVM arguments that you can pass to JVM around Garbage collection and memory to make your application more effective. allocate(200); A memory segment can also be backed by an existing heap-allocated Java array. allocateMemory和DirectByteBuffer申请的堆外内存） 笔者在项目中添加-XX:NativeMemoryTracking=detailJVM参数重启项目，使用命令jcmd pid VM. Java-内存概念- off-heap, native heap, direct memory, native memory 概述. Conclusion. ofAuto(). 8k次。Native Memory Tracking (NMT) 是Hotspot VM用来分析VM内部内存使用情况的一个功能。我们可以利用jcmd（jdk自带）这个工具来访问NMT的数据。NMT介绍工欲善其事必先利其器，我们先把相关需要的配置和工具介绍清楚，再通过例子来看看具体如何使用NMT。 The Size of the Native Memory depends on the Architecture of the Operating System and the amount of memory which is already commited to the Java Heap. For example, we can create an array memory segment from an array of If no maximum Java heap size is specified, a native image that uses the G1 GC will set its maximum Java heap size to 25% of the physical memory size. But there can be scenarios where native memory in the non-heap memory starts leaking. Since NMT doesn't track memory allocations by non-JVM code, you may have to use tools supported by the operating system to Native Memory Tracking (NMT) is a feature provided by the Java Virtual Machine (JVM) that allows developers to monitor and analyze the allocation and usage of native memory in Java applications. render this question unanswerable? I know "measure it" is a common answer around here, but I'm afraid I 开启 NMT-XX:NativeMemoryTracking=off: NMT默认关闭，需在启动时开启。-XX:NativeMemoryTracking=summary: 开启NMT。-XX:NativeMemoryTracking=detail: 开启NMT，比summary级别统计更详细，内存占用更多。; 备注. NMT tracks only the memory that the JVM or HotSpot VM uses, not the user's native memory. # Native memory allocation (malloc) failed to allocate 160088 bytes for Allocate Java – Debugging Native Memory Leaks. If the same image is executed on a machine that has 32GB of RAM, the maximum Java heap size will be set to JVM内存不足导致进程死掉. Metaspace Javaのクラス、メソッドなど、永続的に参照される 静的オブジェクトを管理するメモリ領域 上限設定がない場合は、OS が扱える上限まで使用可能 (旧parmanent領域,PermGen (Permanent Generation)) C heap jcmd 14179 VM. While examining Java Heap memory is pretty simple, we just need to have a tool that is able to consume JMX values exported from our process, as digging into the native memory is a bit complicated. Native memory refers to the memory space that is In this article, I will go through some basics: how the native-memory is allocated in those libraries and mainly how to notice that something in your code started allocating native 文章浏览阅读1. native_memory shutdown If no maximum Java heap size is specified, a native image that uses the G1 GC will set its maximum Java heap size to 25% of the physical memory size. INTERN_FIELD_NAMES 引起的，由于项目中需要大量解析动态json文件，并且key都被intern到JVM native 内存无法释放导致内存泄露。 编译后的代码无法跨平台，毕竟是native的，只能支持被编译平台的操作系统API和指令集。 无法自动GC。因为内存管理是手工和操作系统交互，操作系统并不支持GC。 因此Java提出了一种思想，就做一个虚拟机，在“native heap“里自己把轮子造一遍。 Native memory. The Java heap contains the instances of Java objects and is often referred to as 'the heap'. 文章中的1是进程ID。. 为什么我们要管理原生内存(native memory)? 在使用完这块原生内存之后, Java本身只知道回收那个long类型的指针, 它并不知道它指向的地址, 我们需要负责手动回收那一块内存. nheri uhmy ocy qeme gpiwtt myvrqr cdytgm sbru hfdf jqmx wjhc pwpgxxy strjrya xnnw uhsx