tomcat内存设置及jvm参数调优

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设置tomcat的内存

1、修改 start.bat 中的

call "%EXECUTABLE%" start %CMD_LINE_ARGS%

为 call "%EXECUTABLE%" run %CMD_LINE_ARGS%

2、 catalina.bat 首行加入

set JAVA_OPTS=-server -Xms512m -Xmx512m -XX:NewSize=64m -XX:MaxNewSize=512m -XX:PermSize=256m

-XX:MaxPermSize=256m -XX:+UseParallelGC -XX:ParallelGCThreads=2

-server 以server的模式启动

-Xms 初始化堆内存大小（initial heap size）

-Xmx 最大堆内存大小（maximum heap size）

-XX:NewSize 新生代内存大小

-XX:MaxNewSize 最大新生代内存大小

-XX:PermSize 持久带内存初始化大小

-XX:MaxPermSize持久带内存最大大小

下面三个图很好的阐述了堆内存的分布：新生代eden (young) 老年代tenure（old）持久代（perm）分布示意图如下：

tomcat内存设置及jvm参数调优 - gubaojian - 去创新去开创为世界之光

调优的参数：

Option and Default ValueDescription-XX:+AggressiveOptsTurn on point performance compiler optimizations that are expected to be default in upcoming releases. (Introduced in 5.0 update 6.)-XX:CompileThreshold=10000Number of method invocations/branches before compiling [-client: 1,500]-XX:LargePageSizeInBytes=4mSets the large page size used for the Java heap. (Introduced in 1.4.0 update 1.) [amd64: 2m.]-XX:MaxHeapFreeRatio=70Maximum percentage of heap free after GC to avoid shrinking.-XX:MaxNewSize=sizeMaximum size of new generation (in bytes). Since 1.4, MaxNewSize is computed as a function of NewRatio. [1.3.1 Sparc: 32m; 1.3.1 x86: 2.5m.]-XX:MaxPermSize=64mSize of the Permanent Generation. [5.0 and newer: 64 bit VMs are scaled 30% larger; 1.4 amd64: 96m; 1.3.1 -client: 32m.]-XX:MinHeapFreeRatio=40Minimum percentage of heap free after GC to avoid expansion.-XX:NewRatio=2Ratio of new/old generation sizes. [Sparc -client: 8; x86 -server: 8; x86 -client: 12.]-client: 4 (1.3) 8 (1.3.1+), x86: 12]-XX:NewSize=2mDefault size of new generation (in bytes) [5.0 and newer: 64 bit VMs are scaled 30% larger; x86: 1m; x86, 5.0 and older: 640k]-XX:ReservedCodeCacheSize=32mReserved code cache size (in bytes) - maximum code cache size. [Solaris 64-bit, amd64, and -server x86: 48m; in 1.5.0_06 and earlier, Solaris 64-bit and amd64: 1024m.]-XX:SurvivorRatio=8Ratio of eden/survivor space size [Solaris amd64: 6; Sparc in 1.3.1: 25; other Solaris platforms in 5.0 and earlier: 32]-XX:TargetSurvivorRatio=50Desired percentage of survivor space used after scavenge.-XX:ThreadStackSize=512Thread Stack Size (in Kbytes). (0 means use default stack size) [Sparc: 512; Solaris x86: 320 (was 256 prior in 5.0 and earlier); Sparc 64 bit: 1024; Linux amd64: 1024 (was 0 in 5.0 and earlier); all others 0.]-XX:+UseBiasedLockingEnable biased locking. For more details, see this tuning example. (Introduced in 5.0 update 6.) [5.0: false]-XX:+UseFastAccessorMethodsUse optimized versions of Get<Primitive>Field.-XX:-UseISMUse Intimate Shared Memory. [Not accepted for non-Solaris platforms.] For details, see Intimate Shared Memory.-XX:+UseLargePagesUse large page memory. (Introduced in 5.0 update 5.) For details, see Java Support for Large Memory Pages.-XX:+UseMPSSUse Multiple Page Size Support w/4mb pages for the heap. Do not use with ISM as this replaces the need for ISM. (Introduced in 1.4.0 update 1, Relevant to Solaris 9 and newer.) [1.4.1 and earlier: false]-XX:+UseStringCacheEnables caching of commonly allocated strings.
-XX:AllocatePrefetchLines=1Number of cache lines to load after the last object allocation using prefetch instructions generated in JIT compiled code. Default values are 1 if the last allocated object was an instance and 3 if it was an array.
-XX:AllocatePrefetchStyle=1Generated code style for prefetch instructions.
0 - no prefetch instructions are generate*d*,
1 - execute prefetch instructions after each allocation,
2 - use TLAB allocation watermark pointer to gate when prefetch instructions are executed.
-XX:+UseCompressedStringsUse a byte[] for Strings which can be represented as pure ASCII. (Introduced in Java 6 Update 21 Performance Release)
-XX:+OptimizeStringConcatOptimize String concatenation operations where possible. (Introduced in Java 6 Update 20)