Java 有 39G 的核心转储

Question

我正在 Solarix x86 - 64 位上使用命令行运行 weblogic 服务器：

-Xrs -Xms4096m -Xmx4096m -XX:MaxPermSize=256m -da ...

所以最大堆大小应该是 4G，但是经过一夜，它崩溃并生成了 39G 核心：

-bash-3.00$ ls -l core
-rw-------   1 user group     39017429722 Sep 27 19:47 core

我使用 pmap 转储核心内容：

$ pmap core
core 'core' of 21092:   /opt/middleware/jdk1.6.0_21/bin/amd64/java -Xrs -Xms
0000000000400000         52K r-x--  /opt/middleware/jdk1.6.0_21/bin/amd64/java
000000000041C000          4K rw---  /opt/middleware/jdk1.6.0_21/bin/amd64/java
000000000041D000    2226208K rw---
0000000088225000    2097152K rw---
0000000108225000    4194304K rw---
0000000208225000    8388608K rw---
0000000408225000   16777216K rw---    [ heap ]
FFFFFD7EDF610000        512K rwx--
FFFFFD7EDF77A000         96K rw---    [ stack tid=147 ]
FFFFFD7EDF87B000         96K rw---    [ stack tid=146 ]
FFFFFD7EDF97C000         96K rw---    [ stack tid=145 ]
FFFFFD7EDFA7D000         96K rw---    [ stack tid=144 ]
.....
     total     38102164K

正如你可以看到那里有一个 16G 的堆...为什么会发生这种情况？ java内存泄漏？

jmap dump：

-bash-3.00$ /opt/middleware/jdk1.6.0_21/bin/jmap -heap /opt/middleware/jdk1.6.0_21/bin/java -d64 core
Attaching to core core from executable /opt/middleware/jdk1.6.0_21/bin/java, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 17.0-b16

using thread-local object allocation.
Parallel GC with 4 thread(s)

Heap Configuration:
   MinHeapFreeRatio = 40
   MaxHeapFreeRatio = 70
   MaxHeapSize      = 4294967296 (4096.0MB)
   NewSize          = 1310720 (1.25MB)
   MaxNewSize       = 17592186044415 MB
   OldSize          = 5439488 (5.1875MB)
   NewRatio         = 2
   SurvivorRatio    = 8
   PermSize         = 21757952 (20.75MB)
   MaxPermSize      = 268435456 (256.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 1226899456 (1170.0625MB)
   used     = 396823336 (378.44022369384766MB)
   free     = 830076120 (791.6222763061523MB)
   32.34359050852819% used
From Space:
   capacity = 104726528 (99.875MB)
   used     = 2949120 (2.8125MB)
   free     = 101777408 (97.0625MB)
   2.816020025031289% used
To Space:
   capacity = 100728832 (96.0625MB)
   used     = 0 (0.0MB)
   free     = 100728832 (96.0625MB)
   0.0% used
PS Old Generation
   capacity = 2864709632 (2732.0MB)
   used     = 90771752 (86.56668853759766MB)
   free     = 2773937880 (2645.4333114624023MB)
   3.1686196390043064% used
PS Perm Generation
   capacity = 140509184 (134.0MB)
   used     = 139181296 (132.73362731933594MB)
   free     = 1327888 (1.2663726806640625MB)
   99.05494576069846% used

附加信息：在此核心中加载的so文件：

-bash-3.00$ grep so p.txt|sort -k 4
FFFFFD7FFF3B2000        228K r-x--  /lib/amd64/ld.so.1
FFFFFD7FFF3FB000          8K rwx--  /lib/amd64/ld.so.1
FFFFFD7FFF3FD000          8K rwx--  /lib/amd64/ld.so.1
FFFFFD7EE8100000         32K r-x--  /lib/amd64/libaio.so.1
FFFFFD7EE8118000          4K rw---  /lib/amd64/libaio.so.1
FFFFFD7EE8119000          4K rw---  /lib/amd64/libaio.so.1
FFFFFD7FFF1F0000       1252K r-x--  /lib/amd64/libc.so.1
FFFFFD7FFF339000         36K rw---  /lib/amd64/libc.so.1
FFFFFD7FFF342000         16K rw---  /lib/amd64/libc.so.1
FFFFFD7FFF350000          4K r-x--  /lib/amd64/libdl.so.1
FFFFFD7FFF361000          4K rw---  /lib/amd64/libdl.so.1
FFFFFD7FFE390000          8K r-x--  /lib/amd64/libdoor.so.1
FFFFFD7FFE3A2000          4K rw---  /lib/amd64/libdoor.so.1
FFFFFD7FFE1E0000         28K r-x--  /lib/amd64/libgen.so.1
FFFFFD7FFE1F7000          4K rw---  /lib/amd64/libgen.so.1
FFFFFD7FFE3E0000         16K r-x--  /lib/amd64/libm.so.1
FFFFFD7FFE3F3000          4K rw---  /lib/amd64/libm.so.1
FFFFFD7FFE250000        348K r-x--  /lib/amd64/libm.so.2
FFFFFD7FFE2B6000         24K rw---  /lib/amd64/libm.so.2
FFFFFD7FFE1C0000         48K r-x--  /lib/amd64/libmd.so.1
FFFFFD7FFE1DC000          4K rw---  /lib/amd64/libmd.so.1
FFFFFD7FFE1A0000         16K r-x--  /lib/amd64/libmp.so.2
FFFFFD7FFE1B4000          4K rw---  /lib/amd64/libmp.so.2
FFFFFD7FFE2C0000        664K r-x--  /lib/amd64/libnsl.so.1
FFFFFD7FFE376000         16K rw---  /lib/amd64/libnsl.so.1
FFFFFD7FFE37A000         36K rw---  /lib/amd64/libnsl.so.1
FFFFFD7EE8120000         32K r-x--  /lib/amd64/librt.so.1
FFFFFD7EE8138000          4K rw---  /lib/amd64/librt.so.1
FFFFFD7FFE220000        100K r-x--  /lib/amd64/libscf.so.1
FFFFFD7FFE249000          4K rw---  /lib/amd64/libscf.so.1
FFFFFD7FFF190000         60K r-x--  /lib/amd64/libsocket.so.1
FFFFFD7FFF1AF000          4K rw---  /lib/amd64/libsocket.so.1
FFFFFD7FFF3A0000         20K r-x--  /lib/amd64/libthread.so.1
FFFFFD7FFE200000         36K r-x--  /lib/amd64/libuutil.so.1
FFFFFD7FFE219000          4K rw---  /lib/amd64/libuutil.so.1
FFFFFD7FFF370000         36K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/jli/libjli.so
FFFFFD7FFF388000          8K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/jli/libjli.so
FFFFFD7EE80D0000         64K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libj2pkcs11.so
FFFFFD7EE80EF000          4K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libj2pkcs11.so
FFFFFD7FFDFE0000        188K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libjava.so
FFFFFD7FFE01E000         12K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libjava.so
FFFFFD7EE7DF0000         28K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libmanagement.so
FFFFFD7EE7E06000          4K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libmanagement.so
FFFFFD7EE82A0000         72K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libnet.so
FFFFFD7EE82C1000          8K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libnet.so
FFFFFD7EE8140000         32K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libnio.so
FFFFFD7EE8157000          4K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libnio.so
FFFFFD7FFE030000         68K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libverify.so
FFFFFD7FFE050000          8K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libverify.so
FFFFFD7FFDF70000         64K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libzip.so
FFFFFD7FFDF8F000         12K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/libzip.so
FFFFFD7FFDFC0000         40K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/native_threads/libhpi.so
FFFFFD7FFDFD9000          4K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/native_threads/libhpi.so
FFFFFD7FFDFDA000         20K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/native_threads/libhpi.so
FFFFFD7FFE400000      12932K r-x--  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/server/libjvm.so
FFFFFD7FFF0B2000        628K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/server/libjvm.so
FFFFFD7FFF14F000        112K rw---  /opt/middleware/jdk1.6.0_21/jre/lib/amd64/server/libjvm.so
FFFFFD7FFE3B0000         60K r-x--  /usr/lib/amd64/libCrun.so.1
FFFFFD7FFE3CE000          8K rw---  /usr/lib/amd64/libCrun.so.1
FFFFFD7FFE3D0000         24K rw---  /usr/lib/amd64/libCrun.so.1
FFFFFD7EE8070000         28K r-x--  /usr/lib/amd64/libcryptoutil.so.1
FFFFFD7EE8087000          8K rw---  /usr/lib/amd64/libcryptoutil.so.1
FFFFFD7EE8090000        136K r-x--  /usr/lib/amd64/libpkcs11.so.1
FFFFFD7EE80C2000          4K rw---  /usr/lib/amd64/libpkcs11.so.1
FFFFFD7EE80C3000          4K rw---  /usr/lib/amd64/libpkcs11.so.1
FFFFFD7FFF1C0000          4K r-x--  /usr/lib/amd64/libsched.so.1
FFFFFD7EE8010000        304K r-x--  /usr/lib/security/amd64/pkcs11_softtoken_extra.so.1
FFFFFD7EE806C000         12K rw---  /usr/lib/security/amd64/pkcs11_softtoken_extra.so.1

Answer 1

-Xmx4096m 是java堆的大小。
核心转储是关于整个java虚拟机地址空间进程的。

根据操作系统的不同，您可以获得比预期更大的虚拟寻址空间。所以垃圾场可能会更大。

例如，WindowsXP 为每个进程提供 4GB 地址空间，即使您在 256MB RAM 上运行也是如此。

我认为核心转储大小取决于 Java VM + 操作系统实现。
例如，Solaris 和 Linux 核心转储根本没有任何共同点。

更新：
两种选择：
您是否使用本机库（即非标准的东西）？
如果是这样，请禁用本机扩展并进行一些测试。禁用 Java NIO 也会有所帮助。

如果您使用的是普通的 WebLogic，请尝试一下您的支持：64 位，它在大型部署中还不是很常见，而且您似乎有一个非常大的系统（您的 RAM 比我看到的还多:)