计算机二级辅导:Java虚拟机支持的最大内存限制
发布时间：2010/3/13 9:11:22 来源：城市学习网 编辑：MOON
没想到第一个实验的程序，跑了几个小时，就遇到了Out of Memory Exception了。看看自己的虚拟机设置，我设置的是-Xms512M -Xmx1024M。想都没想，直接改成-Xms512M -Xmx2048M，结果直接就Could not reserve enough space for object heap。程序都起不来了。这才发现原来最大内存还有限制。上网搜了一下，发现很多讨论这个问题的文章。最终在BEA的DEV2DEV发现了最有用的一篇http://dev2dev.bea.com.cn/bbs/thread.jspa?forumID=121&threadID= 35704&start=0&tstart=0
这里的版主YuLimin 做了测试，得出结论：
公司 JVM版本 最大内存(兆)client 最大内存(兆)server
SUN 1.5.x 1492 1520
SUN 1.5.5(Linux) 2634 2660
SUN 1.4.2 1564 1564
SUN 1.4.2(Linux) 1900 1260
IBM 1.4.2(Linux) 2047 N/A
BEA JRockit 1.5 (U3) 1909 1902
我现在用的是JDK1.6. 0_05，测试了一下。在Client状态下最大是，我的JDK不认-Server参数，测试不了Server状态。估计差不多。
SUN 1.6.0 1442 N/a
看样子用Java想用大内存也是不可能的了。而且一般的说法是内存太大了，垃圾收集的时间就会长。这也可以理解，一般是内存不够用了才收集的，扫描2G内存比1G当然要慢多了，而且内存对象多了，估计关系是指数上升的。
下面附上YuLimin的测试方法和测试记录。
测试方法：在命令行下用 java -XmxXXXXM -version 命令来进行测试，然后逐渐的增大XXXX的值，如果执行正常就表示指定的内存大小可用，否则会打印错误信息。
测试记录：
我在Windows 2000 ADS上面测试内存使用的结果如下
SUN的1.2.2、1.3.1、1.4.2、1.5.0、IBM1.4.2、BEA JRockit 1.4.2
F:“JDK“1.2.2“binjava -Xmx700000255M -version
java version “1.2.2″
Classic VM (build JDK-1.2.2_017， native threads， symcjit)
F:“JDK“1.2.2“binjava -Xmx700000256M -version
Bad max heap size: -Xmx700000256M
Could not create the Java virtual machine.
=
F:“JDK“1.3.1“binjava -version
java version “1.3.1_18″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.3.1_18-b01)
Java HotSpot(TM) Client VM (build 1.3.1_18-b01， mixed mode)
F:“JDK“1.3.1“binREM If present， the option to select the VM must be first.
F:“JDK“1.3.1“binREM The default VM is -hotspot.
F:“JDK“1.3.1“binjava -hotspot -Xmx1554M -version
java version “1.3.1_18″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.3.1_18-b01)
Java HotSpot(TM) Client VM (build 1.3.1_18-b01， mixed mode)
F:“JDK“1.3.1“binjava -hotspot -Xmx1555M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
F:“JDK“1.3.1“binjava -server -Xmx1522M -version
java version “1.3.1_18″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.3.1_18-b01)
Java HotSpot(TM) Server VM (build 1.3.1_18-b01， mixed mode)
F:“JDK“1.3.1“binjava -server -Xmx1523M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
F:“JDK“1.3.1“binjava -classic -Xmx2047M -version
java version “1.3.1_18″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.3.1_18-b01)
Classic VM (build 1.3.1_18-b01， native threads， nojit)
F:“JDK“1.3.1“binjava -classic -Xmx2048M -version
Bad max heap size: -Xmx2048M
Could not create the Java virtual machine.
=
F:“JDK“1.4.2“binjava -version
java version “1.4.2_12″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_12-b03)
Java HotSpot(TM) Client VM (build 1.4.2_12-b03， mixed mode)
F:“JDK“1.4.2“binREM The default VM is client.
F:“JDK“1.4.2“binjava -client -Xmx1308M -version
java version “1.4.2_12″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_12-b03)
Java HotSpot(TM) Client VM (build 1.4.2_12-b03， mixed mode)
F:“JDK“1.4.2“binjava -client -Xmx1309M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
F:“JDK“1.4.2“binjava -server -Xmx1308M -version
java version “1.4.2_12″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_12-b03)
Java HotSpot(TM) Server VM (build 1.4.2_12-b03， mixed mode)
F:“JDK“1.4.2“binjava -server -Xmx1309M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
F:“JDK“1.4.2“binREM -hotspot is a synonym for the “client” VM [deprecated]
F:“JDK“1.4.2“binjava -hotspot -Xmx1308M -version
java version “1.4.2_12″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_12-b03)
Java HotSpot(TM) Client VM (build 1.4.2_12-b03， mixed mode)
F:“JDK“1.4.2“binjava -hotspot -Xmx1309M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
=
F:“JDK“1.5.0“binjava -version
java version “1.5.0_07″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.5.0_07-b03)
Java HotSpot(TM) Client VM (build 1.5.0_07-b03， mixed mode， sharing)
F:“JDK“1.5.0“binjava -client -Xmx1492M -version
java version “1.5.0_07″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.5.0_07-b03)
Java HotSpot(TM) Client VM (build 1.5.0_07-b03， mixed mode)
F:“JDK“1.5.0“binjava -client -Xmx1493M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
F:“JDK“1.5.0“binjava -server -Xmx1504M -version
java version “1.5.0_07″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.5.0_07-b03)
Java HotSpot(TM) Server VM (build 1.5.0_07-b03， mixed mode)
F:“JDK“1.5.0“binjava -server -Xmx1505M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
F:“JDK“1.5.0“binREM -hotspot is a synonym for the “client” VM [deprecated]
F:“JDK“1.5.0“binjava -hotspot -Xmx1492M -version
java version “1.5.0_07″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.5.0_07-b03)
Java HotSpot(TM) Client VM (build 1.5.0_07-b03， mixed mode)
F:“JDK“1.5.0“binjava -hotspot -Xmx1493M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
=
F:“JDK“IBM142“binjava -version
java version “1.4.2″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2)
Classic VM (build 1.4.2， J2RE 1.4.2 IBM Windows 32 build cn1420-20040626 (JIT enabled: jitc))
F:“JDK“IBM142“binREM The default VM is client.
F:“JDK“IBM142“binjava -Xmx2047M -version
java version “1.4.2″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2)
Classic VM (build 1.4.2， J2RE 1.4.2 IBM Windows 32 build cn1420-20040626 (JIT enabled: jitc))
F:“JDK“IBM142“binjava -Xmx2048M -version
[ Unable to allocate an initial java heap of 2147483648 bytes. ]
[ **Out of memory， aborting** ]
[ ]
[ *** panic: JVMST016: Cannot allocate memory for initial java heap ]
abnormal program termination
=
F:“BEA“JRockit“binjava -version
java version “1.4.2_05″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_05-b04)
BEA WebLogic JRockit(TM) 1.4.2_05 JVM R24.4.0-1 (build ari-38120-20041118-1131-win-ia32， Native Threads， GC strategy: parallel)
F:“BEA“JRockit“binREM The default VM is jrockit.
F:“BEA“JRockit“binjava -Xmx1617M -version
java version “1.4.2_05″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_05-b04)
BEA WebLogic JRockit(TM) 1.4.2_05 JVM R24.4.0-1 (build ari-38120-20041118-1131-win-ia32， Native Threads， GC strategy: parallel)
F:“BEA“JRockit“binjava -Xmx1618M -version
Unable to acquire some virtual address space - reduced from 1656832 to 1640260 KB!
java version “1.4.2_05″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_05-b04)
BEA WebLogic JRockit(TM) 1.4.2_05 JVM R24.4.0-1 (build ari-38120-20041118-1131-win-ia32， Native Threads， GC strategy: parallel)
F:“BEA“JRockit“binREM -jrockit to select the “jrockit” VM
F:“BEA“JRockit“binjava -jrockit -Xmx1617M -version
java version “1.4.2_05″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_05-b04)
BEA WebLogic JRockit(TM) 1.4.2_05 JVM R24.4.0-1 (build ari-38120-20041118-1131-win-ia32， Native Threads， GC strategy: parallel)
F:“BEA“JRockit“binjava -jrockit -Xmx1618M -version
Unable to acquire some virtual address space - reduced from 1656832 to 1640260 KB!
java version “1.4.2_05″
Java(TM) 2 Runtime Environment， Standard Edition (build 1.4.2_05-b04)
BEA WebLogic JRockit(TM) 1.4.2_05 JVM R24.4.0-1 (build ari-38120-20041118-1131-win-ia32， Native Threads， GC strategy: parallel)
我的测试记录：
C:“java -client -Xmx1441M -version
java version “1.6.0_05″
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
Java HotSpot(TM) Client VM (build 10.0-b19， mixed mode)
C:“java -client -Xmx1442M -version
java version “1.6.0_05″
Java(TM) SE Runtime Environment (build 1.6.0_05-b13)
Java HotSpot(TM) Client VM (build 10.0-b19， mixed mode)
C:“java -client -Xmx1443M -version
Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
C:“java -server -Xmx1443M -version
Error: no `server’ JVM at `C:“Program Files“Java“jre1.6.0_05“bin“server“jvm.dll’.
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