Tomcat性能调优 | Tomcat Performance Tuning

时间 2019-11-29

标签 tomcat 性能 performance tuning 栏目 Tomcat 繁體版

原文原文链接

Tomcat性能调优

修改Tomcat Connector运行模式，优化Tomcat运行性能

Tomcat Connector(Tomcat链接器)有bio、nio、apr三种运行模式

http://www.365mini.com/page/tomcat-connector-mode.htm
1. bio(blocking I/O)，顾名思义，即阻塞式I/O操做，表示Tomcat使用的是传统的Java I/O操做(即java.io包及其子包)。Tomcat在默认状况下，就是以bio模式运行的。遗憾的是，就通常而言，bio模式是三种运行模式中性能最低的一种。经过 Tomcat Manager来查看服务器的当前状态。
http://server206:8080/manager/status
JVM
Free memory: 355.66 MB Total memory: 466.86 MB Max memory: 1016.12 MB
"ajp-apr-8009"
"http-apr-8080"
2. nio(new I/O)，是Java SE 1.4及后续版本提供的一种新的I/O操做方式(即java.nio包及其子包)。Java nio是一个基于缓冲区、并能提供非阻塞I/O操做的Java API，所以nio也被当作是non-blocking I/O的缩写。它拥有比传统I/O操做(bio)更好的并发运行性能。要让Tomcat以nio模式来运行也比较简单，咱们只须要在Tomcat安装目录 /conf/server.xml文件中将以下配置：
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" />
中的protocol属性值改成org.apache.coyote.http11.Http11NioProtocol便可：
<Connector port="8080" protocol="org.apache.coyote.http11.Http11NioProtocol"
connectionTimeout="20000"
redirectPort="8443" />
此时，咱们就能够在Tomcat Manager中看到当前服务器状态页面的HTTP协议的Connector运行模式已经从http-bio-8080变成了http-nio- 8080。
3. apr(Apache Portable Runtime/Apache可移植运行时)，是Apache HTTP服务器的支持库。你能够简单地理解为，Tomcat将以JNI的形式调用Apache HTTP服务器的核心动态连接库来处理文件读取或网络传输操做，从而大大地提升Tomcat对静态文件的处理性能。 Tomcat apr也是在Tomcat上运行高并发应用的首选模式。与配置nio运行模式同样，也须要将对应的Connector节点的protocol属性值改成 org.apache.coyote.http11.Http11AprProtocol。php

Tomcat官方关于三种运行模式的对比

https://tomcat.apache.org/tomcat-7.0-doc/config/http.html#Connector_Comparisonhtml

Java Blocking Connector   Java Non Blocking Connector   APR/native Connector
                                 BIO                         NIO                       APR
    Classname              Http11Protocol             Http11NioProtocol         Http11AprProtocol
    Tomcat Version           3.x onwards                 6.x onwards              5.5.x onwards
    Support Polling              NO                          YES                       YES
    Polling Size                 N/A                   maxConnections             maxConnections
    Read Request Headers      Blocking                  Non Blocking                 Blocking
    Read Request Body         Blocking                    Blocking                   Blocking
    Write Response            Blocking                    Blocking                   Blocking
    Wait for next Request     Blocking                  Non Blocking               Non Blocking
    SSL Support               Java SSL                    Java SSL                   OpenSSL
    SSL Handshake             Blocking                  Non blocking                 Blocking
    Max Connections        maxConnections              maxConnections             maxConnections

如何选择BIO or NIO以及默认设置

https://tomcat.apache.org/tomcat-8.0-doc/config/http.htmljava

When to prefer NIO vs BIO depends on the use case.linux

If you mostly have regular request-response usage, then it doesn’t matter, and even BIO might be a better choice (as seen in my previous benchmarks).
If you have long-living connections, then NIO is the better choice, because it can server more concurrent users without the need to dedicate a blocked thread to each. The poller threads handle the sending of data back to the client, while the worker threads handle new requests. In other words, neither poller, nor worker threads are blocked and reserved by a single user.

Tomcat7和Tomcat8默认设置都是http1.1，Tomcat7默认使用BIO，Tomcat8根据状况自动选择BIO仍是NIO，甚至NIO2.web

The default value is always “HTTP/1.1″, but in Tomcat 7 that “uses an auto-switching mechanism to select either a blocking Java based connector or an APR/native based connector”, while in Tomcat 8 “uses an auto-switching mechanism to select either a non blocking Java NIO based connector or an APR/native based connector”. And to make things even harder, they introduced a NIO2 connector. And to be honest, I don’t know which one of the two NIO connectors is used by default.apache

NIO比BIO并无明显的性能提高 centos

http://techblog.bozho.net/non-blocking-benchmark/ api

“non-blocking doesn’t have visible benefits and one should not force himself to use the possibly unfriendly callback programming model for the sake of imaginary performance gains”tomcat

使用SSL时的APR vs. NIO/BIO服务器

https://blog.eveoh.nl/2012/04/some-notes-on-tomcat-connector-performance/

Tomcat ships with 3 HTTP(s) connectors:

Blocking IO (org.apache.coyote.Http11Protocol): this is the default and most stable connector.
Non-blocking IO (org.apache.coyote.Http11NioProtocol): this is a non-blocking IO connector, which you will need for Comet/WebSockets and should offer slightly better performance in most cases.
APR (org.apache.coyote.Http11AprProtocol): this connector uses Apache Portable Runtime and OpenSSL instead of their Java counterparts. Because of this, performance is generally better, especially when using SSL.

Some conclusions we can draw from these results:

Apache Tomcat performs on a level comparable to Apache HTTPD. This is at least the case for dynamic requests, but I have seen similar results for static requests.
When using SSL: use keep-alive, unless you have a specific reason not to.
When using SSL on Tomcat: use APR.
Don’t expect NIO to give a better performance than BIO out of the box. Benchmark, benchmark, benchmark.

关于Keep-alive设置

maxKeepAliveRequests 　　　If not specified, this attribute is set to 100. 通常设置100~200.

keepAliveTimeout　　　　　　 The default value is to use the value that has been set for the connectionTimeout attribute.

NIO运行模式启动的log

...

INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
Aug 16, 2016 1:38:31 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-nio-8080"]
Aug 16, 2016 1:38:31 PM org.apache.tomcat.util.net.NioSelectorPool getSharedSelector
INFO: Using a shared selector for servlet write/read
Aug 16, 2016 1:38:31 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-nio-8443"]
Aug 16, 2016 1:38:31 PM org.apache.tomcat.util.net.NioSelectorPool getSharedSelector
INFO: Using a shared selector for servlet write/read
Aug 16, 2016 1:38:31 PM org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]

...

Tomcat性能调优之线程池配置

http://jiangzhengjun.iteye.com/blog/852924
线程池配置
<Service name="Catalina">
<Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="500" minSpareThreads="20" maxIdleTime="60000" /> http://zyycaesar.iteye.com/blog/299818
最大线程500（通常服务器足以），最小空闲线程数20，线程最大空闲时间60秒。
<Connector executor="tomcatThreadPool" port="8090" protocol="org.apache.coyote.http11.Http11AprProtocol"
               connectionTimeout="45000" redirectPort="8445" />
or
<Connector executor="tomcatThreadPool" port="80" protocol="HTTP/1.1"
maxThreads="600"
minSpareThreads="100"
maxSpareThreads="300"
               connectionTimeout="60000"
               keepAliveTimeout="15000"
               maxKeepAliveRequests="1"
               redirectPort="443"
               ....../>

http://192.168.1.155:8090/manager/status
默认：
JVM
    Free memory: 74.17 MB Total memory: 149.12 MB Max memory: 227.56 MB
"ajp-apr-8109"
    Max threads: 200 Current thread count: 0 Current thread busy: 0 Keeped alive sockets count: 0
     Max processing time: 0 ms Processing time: 0.0 s Request count: 0 Error count: 0 Bytes received: 0.00 MB Bytes sent: 0.00 MB

"http-apr-8090"
    Max threads: 200 Current thread count: 10 Current thread busy: 1 Keeped alive sockets count: 2
     Max processing time: 702 ms Processing time: 3.743 s Request count: 83 Error count: 3 Bytes received: 0.00 MB Bytes sent: 0.35 MB
配置线程池以后：
JVM
    Free memory: 76.36 MB Total memory: 153.81 MB Max memory: 227.56 MB
"ajp-apr-8109"
    Max threads: 200 Current thread count: 0 Current thread busy: 0 Keeped alive sockets count: 0
    Max processing time: 0 ms Processing time: 0.0 s Request count: 0 Error count: 0 Bytes received: 0.00 MB Bytes sent: 0.00 MB
"http-apr-8090"
    Max threads: 500 Current thread count: 2 Current thread busy: 1 Keeped alive sockets count: 0
    Max processing time: 0 ms Processing time: 0.0 s Request count: 0 Error count: 0 Bytes received: 0.00 MB Bytes sent: 0.00 MB

Linux下查看tomcat链接数
netstat -na | grep ESTAB | grep 8080 | wc -l
$ netstat -na | grep ESTAB | grep 8090 | wc -l
2
$ netstat -na | grep ESTAB | grep 8090
tcp        0      0 123.56.104.184:8090         111.205.208.29:50634        ESTABLISHED
tcp        0      0 123.56.104.184:8090         111.205.208.29:50635        ESTABLISHED
tcp        0      0 123.56.104.184:8090         111.205.208.29:50633        ESTABLISHED
查看Manager Status： "http-bio-8090"，显示thread count为3，是一致，以下：
Max threads: 500 Current thread count: 20 Current thread busy: 3

Tomcat性能调优之APR （Apache Portable Runtime）配置

allows Tomcat to use certain native resources for performance
http://tomcat.apache.org/native-doc/
若是没装启动Tomcat时候，Catalina.out:
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/lib
1. install APR
In rpm based Linux those dependencies could be installed by something like:
yum install apr-devel openssl-devel
==========================================================================================================================
Package                            Arch                  Version                            Repository              Size
==========================================================================================================================
Installing:
apr-devel                          x86_64                1.3.9-5.el6_2                      base                   176 k
openssl-devel                      x86_64                1.0.1e-30.el6_6.4                  updates                1.2 M
Installing for dependencies:
apr                                x86_64                1.3.9-5.el6_2                      base                   123 k
keyutils-libs-devel                x86_64                1.4-5.el6                          base                    29 k
krb5-devel                         x86_64                1.10.3-33.el6                      base                   498 k
libcom_err-devel                   x86_64                1.41.12-21.el6                     base                    32 k
libselinux-devel                   x86_64                2.0.94-5.8.el6                     base                   137 k
libsepol-devel                     x86_64                2.0.41-4.el6                       base                    64 k
zlib-devel                         x86_64                1.2.3-29.el6                       base                    44 k
Updating for dependencies:
e2fsprogs                          x86_64                1.41.12-21.el6                     base                   553 k
e2fsprogs-libs                     x86_64                1.41.12-21.el6                     base                   121 k
keyutils-libs                      x86_64                1.4-5.el6                          base                    20 k
krb5-libs                          x86_64                1.10.3-33.el6                      base                   765 k
libcom_err                         x86_64                1.41.12-21.el6                     base                    37 k
libselinux                         x86_64                2.0.94-5.8.el6                     base                   108 k
libselinux-utils                   x86_64                2.0.94-5.8.el6                     base                    82 k
libss                              x86_64                1.41.12-21.el6                     base                    41 k
openssl                            x86_64                1.0.1e-30.el6_6.4                  updates                1.5 M

Transaction Summary
==========================================================================================================================
Install       9 Package(s)
Upgrade       9 Package(s)

Total download size: 5.4 M
Is this ok [y/N]: y
Downloading Packages:
(1/18): apr-1.3.9-5.el6_2.x86_64.rpm                                                               | 123 kB     00:00
(2/18): apr-devel-1.3.9-5.el6_2.x86_64.rpm                                                         | 176 kB     00:04
(3/18): e2fsprogs-1.41.12-21.el6.x86_64.rpm                                                        | 553 kB     00:00
(4/18): e2fsprogs-libs-1.41.12-21.el6.x86_64.rpm                                                   | 121 kB     00:02
(5/18): keyutils-libs-1.4-5.el6.x86_64.rpm                                                         | 20 kB     00:00
(6/18): keyutils-libs-devel-1.4-5.el6.x86_64.rpm                                                   | 29 kB     00:00
(7/18): krb5-devel-1.10.3-33.el6.x86_64.rpm                                                        | 498 kB     00:00
(8/18): krb5-libs-1.10.3-33.el6.x86_64.rpm                                                         | 765 kB     00:00
(9/18): libcom_err-1.41.12-21.el6.x86_64.rpm                                                       | 37 kB     00:00
(10/18): libcom_err-devel-1.41.12-21.el6.x86_64.rpm                                                | 32 kB     00:00
(11/18): libselinux-2.0.94-5.8.el6.x86_64.rpm                                                      | 108 kB     00:00
(12/18): libselinux-devel-2.0.94-5.8.el6.x86_64.rpm                                                | 137 kB     00:03
(13/18): libselinux-utils-2.0.94-5.8.el6.x86_64.rpm                                                | 82 kB     00:00
(14/18): libsepol-devel-2.0.41-4.el6.x86_64.rpm                                                    | 64 kB     00:00
(15/18): libss-1.41.12-21.el6.x86_64.rpm                                                           | 41 kB     00:00
(16/18): openssl-1.0.1e-30.el6_6.4.x86_64.rpm                                                      | 1.5 MB     00:00
(17/18): openssl-devel-1.0.1e-30.el6_6.4.x86_64.rpm                                                | 1.2 MB     00:41
(18/18): zlib-devel-1.2.3-29.el6.x86_64.rpm                                                        | 44 kB     00:00
--------------------------------------------------------------------------------------------------------------------------
Total                                                                                      43 kB/s | 5.4 MB     02:09

[root@iZ94gt8lzgnZ logs]# rpm -ql apr
/usr/lib64/libapr-1.so.0
/usr/lib64/libapr-1.so.0.3.9
/usr/share/doc/apr-1.3.9
/usr/share/doc/apr-1.3.9/CHANGES
/usr/share/doc/apr-1.3.9/LICENSE
/usr/share/doc/apr-1.3.9/NOTICE

[root@iZ94gt8lzgnZ native]# rpm -ql apr-devel
/usr/bin/apr-1-config
/usr/include/apr-1
/usr/include/apr-1/apr-x86_64.h
/usr/include/apr-1/apr.h
/usr/include/apr-1/apr_allocator.h
/usr/include/apr-1/apr_atomic.h
/usr/include/apr-1/apr_dso.h
/usr/include/apr-1/apr_env.h
/usr/include/apr-1/apr_errno.h
/usr/include/apr-1/apr_file_info.h
/usr/include/apr-1/apr_file_io.h
/usr/include/apr-1/apr_fnmatch.h
/usr/include/apr-1/apr_general.h
/usr/include/apr-1/apr_getopt.h
/usr/include/apr-1/apr_global_mutex.h
/usr/include/apr-1/apr_hash.h
/usr/include/apr-1/apr_inherit.h
/usr/include/apr-1/apr_lib.h
/usr/include/apr-1/apr_mmap.h
/usr/include/apr-1/apr_network_io.h
/usr/include/apr-1/apr_poll.h
/usr/include/apr-1/apr_pools.h
/usr/include/apr-1/apr_portable.h
/usr/include/apr-1/apr_proc_mutex.h
/usr/include/apr-1/apr_random.h
/usr/include/apr-1/apr_ring.h
/usr/include/apr-1/apr_shm.h
/usr/include/apr-1/apr_signal.h
/usr/include/apr-1/apr_strings.h
/usr/include/apr-1/apr_support.h
/usr/include/apr-1/apr_tables.h
/usr/include/apr-1/apr_thread_cond.h
/usr/include/apr-1/apr_thread_mutex.h
/usr/include/apr-1/apr_thread_proc.h
/usr/include/apr-1/apr_thread_rwlock.h
/usr/include/apr-1/apr_time.h
/usr/include/apr-1/apr_user.h
/usr/include/apr-1/apr_version.h
/usr/include/apr-1/apr_want.h
/usr/lib64/apr-1
/usr/lib64/apr-1/build
/usr/lib64/apr-1/build/apr_rules.mk
/usr/lib64/apr-1/build/libtool
/usr/lib64/apr-1/build/make_exports.awk
/usr/lib64/apr-1/build/make_var_export.awk
/usr/lib64/apr-1/build/mkdir.sh
/usr/lib64/libapr-1.la
/usr/lib64/libapr-1.so
/usr/lib64/pkgconfig/apr-1.pc
/usr/share/aclocal/find_apr.m4
/usr/share/doc/apr-devel-1.3.9
/usr/share/doc/apr-devel-1.3.9/APRDesign.html
/usr/share/doc/apr-devel-1.3.9/canonical_filenames.html
/usr/share/doc/apr-devel-1.3.9/incomplete_types
/usr/share/doc/apr-devel-1.3.9/non_apr_programs

http://wander312.iteye.com/blog/1132975
/usr/lib64已经在path里面了，不用加了：
vi /etc/profile
# 后面添加如下内容
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib64
# 使profile生效，
source /etc/profile
2. install Tomcat Native Connector
wget http://mirrors.cnnic.cn/apache/tomcat/tomcat-connectors/native/1.1.32/source/tomcat-native-1.1.32-src.tar.gz
tar zxvf tomcat-native-1.1.32-src.tar.gz
cd tomcat-native-1.1.32-src/jni/native
./configure --with-apr=/usr/bin/apr-1-config --with-java-home=/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.65.x86_64 --with-ssl=/usr/bin/openssl --prefix=/root/apache-tomcat-7.0.57

[root@iZ94gt8lzgnZ ~]# ls /usr/lib/jvm
java-1.7.0-openjdk-1.7.0.65.x86_64 jre jre-1.7.0 jre-1.7.0-openjdk.x86_64 jre-openjdk
[root@iZ94gt8lzgnZ native]# ls /usr/bin/open*
/usr/bin/open /usr/bin/openssl /usr/bin/openvt

3. 启动 tomcat 后，看日志：
bin/startup.sh
head logs/catalina.out
能够看到如下结果：
信息: Loaded APR based Apache Tomcat Native library 1.1.14.
2009-1-13 11:12:51 org.apache.catalina.core.AprLifecycleListener init
信息: APR capabilities: IPv6 [true], sendfile [true], accept filters [false], random [true].

Linux下查看tomcat链接数
netstat -na | grep ESTAB | grep 8080 | wc -l
$ netstat -na | grep ESTAB | grep 8090 | wc -l
2
$ netstat -na | grep ESTAB | grep 8090
tcp        0      0 123.56.104.184:8090         111.205.208.29:50634        ESTABLISHED
tcp        0      0 123.56.104.184:8090         111.205.208.29:50635        ESTABLISHED
tcp        0      0 123.56.104.184:8090         111.205.208.29:50633        ESTABLISHED
查看Manager Status： "http-bio-8090"，显示thread count为3，是一致，以下：
Max threads: 500 Current thread count: 20 Current thread busy: 3

Tomcat JVM性能调优

关于JVM

整个JVM内存大小=年轻代大小 + 年老代大小 + 持久代大小.(1536+512=2g)

Sun官方推荐年轻代配置为整个堆的3/8。

JVM内存构成说明

JVM Heap memory elements	JVM Non-Heap memory parts
Eden Space: The pool from which memory is initially allocated for most objects.	Permanent Generation: The pool containing all the reflective data of the virtual machine itself, such as class and method objects. With Java VMs that use class data sharing, this generation is divided into read-only and read-write areas.
Survivor Space: The pool containing objects that have survived the garbage collection of the Eden space. This space is divided to ‘From Space’ and ‘To Space’ (for example in jmap output).	Code Cache: The HotSpot Java VM also includes a code cache, containing memory that is used for compilation and storage of native code.
Tenured Generation/PS Old Gen: The pool containing objects that have existed for some time in the survivor space.

JVM内存构成图解

Below diagram illustrates JVM memory parts and JVM (java) related command line switches used to preset/limit some of them.

- See more at: http://www.jvmhost.com/articles/how-can-i-monitor-memory-usage-of-my-tomcat-jvm#sthash.Ctd36Kca.dpuf

NewRatio在不一样平台的推荐值

https://blogs.oracle.com/jonthecollector/entry/the_second_most_important_gc

If your application has a large proportion of long lived data, the value of NewRatio may not put enough of the space into the tenured generation.

Something to add here is that the default value of NewRatio is platform dependent and runtime compiler (JIT) dependent. Below are the values as we get ready for the JDK6 release.

-server on amd64 2

-server on ia32 8

-server on sparc 2

-client on ia32 12

-client on sparc 8

IBM的Heap Analyser

G1GC

JDK7新特性之

http://dongliu.net/post/404142

Garbage-first garbage collector，简称G1 GC，是最终将用于代替Concurrent Mark-Sweep garbage collector(CMS GC)的新一代垃圾回收器。

目前JDK1.6update14及之后版本的jvm中已经继承了G1 GC，可使用参数-XX:+UnlockExperimentalVMOptions -XX:+UseG1GC来启用。

https://blogs.oracle.com/g1gc/

JVM内存限制(最大值)

在命令行下用 java -XmxXXXXM -version 命令来进行测试，而后逐渐的增大XXXX的值，若是执行正常就表示指定的内存大小可用，不然会打印错误信息。

http://unixboy.iteye.com/blog/174173

Tomcat JVM 调优记录

Tomcat 20150616配置和状态

整个JVM内存大小=年轻代大小 + 年老代大小 + 持久代大小

Note：Tomcat从20150604启动，20150612 reload DDTService。

$ cat /opt/tomcat-ddtservice/bin/setenv.sh

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms512m -Xmx2048m -XX:PermSize=128m -XX:MaxPermSize=768m"

admin@.184:~]

$ ps -auxw --sort=%cpu

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

root 17733 0.1 0.1 991520 10048 ? Sl May20 76:51 /usr/local/aegis/alihids/AliHids

root 18847 0.2 0.1 793852 13936 ? Sl Apr03 249:44 /usr/local/aegis/aegis_client/aegis_00_73/AliYunDun

admin 20880 0.8 33.3 5557668 2686652 ? Sl Jun04 146:14 /opt/jdk1.7.0_71/bin/java -Djava.util.logging.config.file=/opt/tomca

admin 2480 3.0 7.2 3926212 584256 ? Sl Jan06 7151:06 /opt/jdk1.7.0_71/bin/java -Djava.util.logging.config.file=/opt/apac

admin@.184:~]

$ free

total used free shared buffers cached

Mem: 8058260 7873136 185124 0 149520 4179732

-/+ buffers/cache: 3543884 4514376

Swap: 0 0 0

http://.28:8161/admin/subscribers.jsp

Active Durable Topic Subscribers

http://.184:8090/manager/status

*Server Information*
Tomcat Version	JVM Version	JVM Vendor	OS Name	OS Version	OS Architecture	Hostname	IP Address
Apache Tomcat/7.0.57	1.7.0_71-b14	Oracle Corporation	Linux	2.6.32-358.6.2.el6.x86_64	amd64	iZ25f12r4xgZ	10.170.207.50

"ajp-bio-8209"

Max threads: 200 Current thread count: 0 Current thread busy: 0
Max processing time: 0 ms Processing time: 0.0 s Request count: 0 Error count: 0 Bytes received: 0.00 MB Bytes sent: 0.00 MB

"http-bio-8090"

Max threads: 500 Current thread count: 28 Current thread busy: 18
Max processing time: 1320993 ms Processing time: 24161.775 s Request count: 380932 Error count: 63077 Bytes received: 55.11 MB Bytes sent: 3862.71 MB

JVM

Free memory: 1377.64 MB Total memory: 1899.50 MB Max memory: 1899.50 MB

Memory Pool	Type	Initial	Total	Maximum	Used
PS Eden Space	Heap memory	129.00 MB	530.50 MB	674.50 MB	26.95 MB (3%)
PS Old Gen	Heap memory	341.50 MB	1365.00 MB	1365.00 MB	446.50 MB (32%)
PS Survivor Space	Heap memory	21.00 MB	4.00 MB	4.00 MB	0.00 MB (0%)
Code Cache	Non-heap memory	2.43 MB	45.37 MB	48.00 MB	44.79 MB (93%)
PS Perm Gen	Non-heap memory	128.00 MB	310.00 MB	768.00 MB	309.57 MB (40%)

Tomcat 20150616 问题

系统剩余内存太少。（185M）
Code Cache used太高，接近上限。（ReservedCodeCacheSize and InitialCodeCacheSize）
PS Perm Gen（Permanent Generation）只用到一半不到，基本不会再增加。
Heap memory整体使用不到一半。
服务器通常设置-Xms、-Xmx相等以免在每次GC 后调整堆的大小。

Tomcat 20150616 调整

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms512m -Xmx2048m -XX:PermSize=128m -XX:MaxPermSize=768m"

调整为：

export JAVA_OPTS="-Dfile.encoding=UTF-8 –Xms1024m -Xmx1536m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:ReservedCodeCacheSize=128m"

Tomcat 20150616 调整后跟踪

20150618上线以后测试完毕22：00

JVM

Free memory: 1245.49 MB Total memory: 1436.00 MB Max memory: 1436.00 MB

Memory Pool	Type	Initial	Total	Maximum	Used
PS Eden Space	Heap memory	384.00 MB	311.50 MB	311.50 MB	61.70 MB (19%)
PS Old Gen	Heap memory	1024.00 MB	1024.00 MB	1024.00 MB	121.35 MB (11%)
PS Survivor Space	Heap memory	64.00 MB	100.50 MB	100.50 MB	7.44 MB (7%)
Code Cache	Non-heap memory	2.43 MB	9.43 MB	128.00 MB	9.24 MB (7%)
PS Perm Gen	Non-heap memory	256.00 MB	256.00 MB	512.00 MB	74.74 MB (14%)

20150619上线以后测试完毕16：47

JVM

Free memory: 1199.51 MB Total memory: 1508.50 MB Max memory: 1508.50 MB

Memory Pool	Type	Initial	Total	Maximum	Used
PS Eden Space	Heap memory	384.00 MB	456.50 MB	456.50 MB	53.91 MB (11%)
PS Old Gen	Heap memory	1024.00 MB	1024.00 MB	1024.00 MB	247.09 MB (24%)
PS Survivor Space	Heap memory	64.00 MB	28.00 MB	28.00 MB	7.96 MB (28%)
Code Cache	Non-heap memory	2.43 MB	19.62 MB	128.00 MB	18.88 MB (14%)
PS Perm Gen	Non-heap memory	256.00 MB	256.00 MB	512.00 MB	98.51 MB (19%)

20150629 10:30(6月19日晚上重启过)上线后10天

JVM

Free memory: 1180.61 MB Total memory: 1470.50 MB Max memory: 1470.50 MB

Memory Pool	Type	Initial	Total	Maximum	Used
PS Eden Space	Heap memory	384.00 MB	420.00 MB	439.00 MB	16.91 MB (3%)
PS Old Gen	Heap memory	1024.00 MB	1024.00 MB	1024.00 MB	246.81 MB (24%)
PS Survivor Space	Heap memory	64.00 MB	26.50 MB	26.50 MB	26.15 MB (98%)
Code Cache	Non-heap memory	2.43 MB	27.00 MB	128.00 MB	26.58 MB (20%)
PS Perm Gen	Non-heap memory	256.00 MB	256.00 MB	512.00 MB	121.63 MB (23%)

20150629 10:33

Free memory: 972.35 MB Total memory: 1492.00 MB Max memory: 1492.00 MB

Memory Pool	Type	Initial	Total	Maximum	Used
PS Eden Space	Heap memory	384.00 MB	421.50 MB	421.50 MB	274.89 MB (65%)
PS Old Gen	Heap memory	1024.00 MB	1024.00 MB	1024.00 MB	244.74 MB (23%)
PS Survivor Space	Heap memory	64.00 MB	46.50 MB	46.50 MB	0.00 MB (0%)
Code Cache	Non-heap memory	2.43 MB	27.00 MB	128.00 MB	26.59 MB (20%)
PS Perm Gen	Non-heap memory	256.00 MB	256.00 MB	512.00 MB	121.57 MB (23%)

整个JVM内存大小=年轻代大小 + 年老代大小 + 持久代大小.(1536+512=2g)

Sun官方推荐年轻代配置为整个堆的3/8。

-Xmn2g：设置年轻代大小为2G。

-XX:NewRatio=4:设置年轻代（包括Eden和两个Survivor区）与年老代的比值（除去持久代）。设置为4，则年轻代与年老代所占比值为1：4，年轻代占整个堆栈的1/5

-XX:SurvivorRatio=4：设置年轻代中Eden区与Survivor区的大小比值。设置为4，则两个Survivor区与一个Eden区的比值为2:4，一个Survivor区占整个年轻代的1/6

-Xss128k：设置每一个线程的堆栈大小。JDK5.0之后每一个线程堆栈大小为1M，之前每一个线程堆栈大小为256K。

-XX:NewRation=1设为1是由于PS Eden Space上下浮动很大，同时PS Old Gen却无变化，说明建立了不少新对象以后很快被回收；所以应该调大Eden Space.

Tomcat 再次调整

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms512m -Xmx2048m -XX:PermSize=128m -XX:MaxPermSize=768m"

调整为：

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms1024m -Xmx1536m -XX:PermSize=256m -XX:MaxPermSize=512m -XX:ReservedCodeCacheSize=128m"

调整为：

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms1536m -Xmx1536m -XX:NewRatio=1 -XX:PermSize=256m -XX:MaxPermSize=512m -XX:ReservedCodeCacheSize=128m –Xss256k "

export JAVA_OPTS="-Dfile.encoding=UTF-8 -Xms1536m -Xmx1536m -XX:NewRatio=1 -XX:SurvivorRatio=6 -XX:PermSize=256m -XX:MaxPermSize=512m -Xss256k -XX:ReservedCodeCacheSize=128m "

tomcat+java的web程序持续占cpu问题调试

解决方法：
一、先用top查看占用cpu的进程id
二、再用ps -ef | grep PID定位具体的进程主体；如是不是tomcat启动的java程序
三、用ps -mp pid -o THREAD,tid,time打印出该进程下的线程占用cpu状况
       找到了耗时最高的线程28802，占用CPU时间快两个小时了！
四、其次将须要的线程ID转换为16进制格式：printf "%x\n" tid
五、最后打印线程的堆栈信息：jstack pid | grep tid -A 30
       找到出现问题的代码，并分析具体函数中是否有可能出现死循环的代码段。
       一般问题出如今while， for之类的循环代码片断。

jstack command not found on centos
[root@yfddt5Z logs]# sudo updatedb
[root@yfddt5Z logs]# locate jstack
/usr/java/jdk1.7.0_79/bin/jstack
/usr/java/jdk1.7.0_79/man/ja_JP.UTF-8/man1/jstack.1
/usr/java/jdk1.7.0_79/man/man1/jstack.1

Reference:

http://blog.csdn.net/netdevgirl/article/details/53943224 jstack(查看线程)、jmap(查看内存)和jstat(性能分析)命令

Tomcat性能调优 | Tomcat Performance Tuning

Tomcat性能调优

修改Tomcat Connector运行模式，优化Tomcat运行性能

Tomcat Connector(Tomcat链接器)有bio、nio、apr三 种运行模式

Tomcat官方关于三种运行模式的对比

如何选择BIO or NIO以及默认设置

NIO运行模式启动的log

Tomcat性能调优之线程池配置

Tomcat性能调优之APR （Apache Portable Runtime）配置

Tomcat JVM性能调优

关于JVM

JVM内存构成说明

JVM内存构成图解

NewRatio在不一样平台的推荐值

IBM的Heap Analyser

G1GC

JVM内存限制(最大值)

Tomcat JVM 调优记录

Tomcat 20150616配置和状态

Tomcat 20150616 问题

Tomcat 20150616 调整

Tomcat 20150616 调整后跟踪

20150618上线以后测试完毕22：00

20150619上线以后测试完毕16：47

20150629 10:30(6月19日晚上重启过)上线后10天

20150629 10:33

Tomcat 再次调整

tomcat+java的web程序持续占cpu问题调试

Tomcat Connector(Tomcat链接器)有bio、nio、apr三种运行模式