tomcat性能调优
性能调优:主要从以下几个方面入手
- 应用代码:假如代码开发的不好,它会导致性能问题,比如数据库的连接在该关闭的时候没有适当的关闭,将会导致应用运行慢。
- 数据库的调优:如果数据库的响应比较慢,那么应用也肯定就会回应的比较慢了。
- JVM的调优:假如应用需要较多的内存来运行,而你分配比较小的内存,那么就会导致内存溢出,因而也会导致性能问题。
- 中间件服务:比如我们在选择消息队列,缓存或者设计好时,也会导致性能问题。
- 基础架构和OS:比如,网络丢包,系统配置不合理等。
适当的日志记录和监控:日志和监控有助于分析和排错。
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Tomcat连接器的类型:
Java HTTP 连接器:
是基于HTTP协议,支持HTTP1.1,它使tomcat服务器扮演一个独立 服务器和JSP/servlet功能的服务器。
Java AJP 连接器:
JAVA AJP是基于Apache JServ 协议的,该连接器常常是在你不想暴露自己的Java servlet容器到Internet.
APR(AJP/HTTP)连接器:
Apache Portable Runtime(APR)是在扩容,性能和不同web服务器之间的兼容最好 的。它提供了比如OPENSSL,共享内存,Unix大套接字等。
线程调优:
线程沲定义了web服务器连接请求连接的数量,可以定义两种线程沲:一是共享沲,二是专用沲。该配置在TOMCAT_HOME/conf/server.xml文件中定义的。
共享线程沲:
假如你配置了四个连接器,那么你可以共享使用这个线程沲。
配置如下:
(1)定义线程沲
(2)引用定义的线程沲
专用线程沲:也是在server.xml文件中进行定义的
下表是专用线程沲和共享线程沲经常使用场景对比
- Features Shared thread pool Dedicated thread pool
- Number of users less High
- Environment Development Production
- Performance low Good
maxThreads:
默认定义的最大线程沲是150个,在生产环境中,可以根据服务器的性能来调下该参数。
maxKeepAlive:
也相当于并发数一样,默认值是1,也就是相当于关闭。
JVM的调优:
JMAP(内存映射)
JMAP显示共享JAVA虚拟机内存信息,对查看共享内存的状态有用的。下面是一些常用选项:
Options Description
- -dump Dumps the Java heap in hprof binary format
- -finalizer info Prints information on objects awaiting finalization
- -heap Prints a heap summary
- -histo Prints a histogram of the heap
- -permstat Prints class loader-wise statistics of permanent generation of the Java heap
jmap的语法:
./jmap --heap
比如我们的JAVA的ID是4306,那么就执行./jmap -heap 4306
Attaching to process ID 4306, please wait...
Debugger attached successfully.
Client compiler detected.
JVM version is 19.1-b02
using thread-local object allocation.
Mark Sweep Compact GC
Heap Configuration:
MinHeapFreeRatio = 40
MaxHeapFreeRatio = 70
MaxHeapSize = 268435456 (256.0MB)
NewSize = 1048576 (1.0MB)
MaxNewSize = 4294901760 (4095.9375MB)
OldSize = 4194304 (4.0MB)
NewRatio = 2
SurvivorRatio = 8
PermSize = 12582912 (12.0MB)
MaxPermSize = 67108864 (64.0MB)
Heap Usage:
New Generation (Eden + 1 Survivor Space):
capacity = 5111808 (4.875MB)
used = 3883008 (3.703125MB)
free = 1228800 (1.171875MB)
75.96153846153847% used
Eden Space:
capacity = 4587520 (4.375MB)
used = 3708360 (3.5365676879882812MB)
free = 879160 (0.8384323120117188MB)
80.83583286830357% used
From Space:
capacity = 524288 (0.5MB)
used = 174648 (0.16655731201171875MB)
free = 349640 (0.33344268798828125MB)
33.31146240234375% used
To Space:
capacity = 524288 (0.5MB)
used = 0 (0.0MB)
free = 524288 (0.5MB)
0.0% used
tenured generation:
capacity = 11206656 (10.6875MB)
used = 3280712 (3.1287307739257812MB)
free = 7925944 (7.558769226074219MB)
29.274673908077485% used
Perm Generation:
capacity = 12582912 (12.0MB)
used = 6639016 (6.331459045410156MB)
free = 5943896 (5.668540954589844MB)
52.762158711751304% used
从上面看可以看到如下主要信息:
- 应用的堆配置
- 每个JVM组件的堆内存利用率
- 垃圾收集器使用的算法
堆内存的配置:
在catalina.sh中JAVA_OPTS的选项。JAVA_OPTS="-Xms128m -Xmx512m -XX:MaxPermSize=256m"
垃圾收集器主要有三种方式:
- 串行收集
- 并行收集
- 并发低暂停收集
串行收集的特征如下:
- Features Serial collector
- Process Single thread is used for GC
- GC pause High
- Threading Single threaded
- Application Small application (data less than 100 MB)
- Advantage There is single thread communication
并行收集的特征如下:
- Features Parallel collector
- Process Parallel thread does minor GC
- GC pause Less than Serial
- Threading Multithreaded
- Application Mid-large
- Advantage Used in applications when peak performance is needed
并发收集的特征如下:
- Features Concurrent collector
- Process GC is done concurrently
- GC pause Short pause
- Threading Multithreaded
- Application Mid-large
- Advantage Used in applications when a response is needed
JVM的选项分为标准和非标准:
主要有以下选项:
- Options Parameter Description
- Behavioral Options -XX:+ScavengeBeforeFullGC Do young generation GC prior to a full GC
- Behavioral Options --XX:-UseParallelGC Use parallel garbage collection for scavenges
- Performance Options -XX:MaxNewSize=size Maximum size of new generation (in bytes)
- Performance Options -XX:MaxPermSize=64m Size of the Permanent Generation (after exceeding Xmxvalue)
- Performance Options -Xms Minimum heap memory for the startup of Tomcat
- Performance Options Xmx Maximum memory allocated to the instance
- Performance Options -Xss Stack size for the heap
- Debugging Options -XX:-CITime Prints time spent in the JIT Compiler
- Debugging Options -XX:ErrorFile=./hs_err_pid
.log If an error occurs, save the error data to this file - Debugging Options -XX:HeapDumpPath=./java_pid
.hprof Path to the directory or filename for the heap dump - Debugging Options -XX:-HeapDumpOnOutOfMemoryError Dump the heap to the file whenjava.lang.OutOfMemoryError is thrown
- Options Parameter Description
- Debugging Options -XX:OnError="
; " Run user-defined commands on fatal error - Debugging Options -XX:OnOutOfMemoryError="
; Run user-defined commands when an OutOfMemoryError is first thrown - Debugging Options -XX:-PrintClassHistogram Print a histogram of class instances on Ctrl-Break
- Parameters displayed in the logs for GC
- GC prints the output of the garbage collection to the stdout stream. At every garbage collection, the following five fields are printed:
[%T %B->%A(%C), %D]
- %T: This is "GC" when the garbage collection is a scavenge, and "Full GC:" is performed, then scavenge collects live objects from the new generation only, whereas a full garbage collection collects objects from all spaces in the Java heap.
- %B: It is the size of the Java heap used before the garbage collection, in KB.
- %A: It is the size of the Java heap after the garbage collection, in KB.
- %C: It is the current capacity of the entire Java heap, in KB.
%D: It is the duration of the collection in seconds.
- SurvivorRatio
- It is defined as a ratio of eden to the survivor space size. The default value is 8, meaning that eden is 8 times bigger than from and to, each. The syntax for the SurvivorRatio is -XX:SurvivorRatio=
. - The following are some examples:
系统调优:
- 建议选择64位系统
- 文件尺寸限制
- 打开连接限制
- 大页面尺寸
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