tomcat7 优化

快来打我* 2022-06-17 02:21 162阅读 0赞

最近面试的时候遇到了这个问题，在这里进行一个简单总结，希望对小伙伴们以后的工作有帮助。

# 1. **目的** #

通过优化tomcat提高网站的并发能力。

# 2. **服务器资源** #

服务器所能提供CPU、内存、硬盘的性能对处理能力有决定性影响。

# 3. **优化配置** #

## 3.1. **配置tomcat管理员账户** ##

在conf/ tomcat-users.xml下添加用户：

启动tomcat，登录查看信息：

[http://127.0.0.1:8080/][http_127.0.0.1_8080]

## 3.1 **tomcat的3种运行模式** ##

tomcat的运行模式有3种：

1、 bio  
默认的模式,性能非常低下,没有经过任何优化处理和支持.

2、 nio  
利用java的异步io护理技术,no blocking IO技术.

3、 apr  
安装起来最困难,但是从操作系统级别来解决异步的IO问题,大幅度的提高性能.

### 3.2.1. **启动NIO模式** ###

修改server.xml里的Connector节点,修改protocol为org.apache.coyote.http11.Http11NioProtocol

![Image 1][]

## 3.3 **执行器（线程池）** ##

在tomcat中每一个用户请求都是一个线程，所以可以使用线程池提高性能。

### 3.3.1. **开启并且使用** ###

配置：

![Image 1][]

3.3.2**参数说明**

3.3.3**最佳实践**

**![Image 1][]**

###  ###

## 3.4 **连接器（Connector）** ##

## Connector是Tomcat接收请求的入口，每个Connector有自己专属的监听端口 ##

##  Connector有两种：HTTP Connector和AJP Connector ##

### 3.4.1. **通用属性（高亮的是重点）** ###

### 3.4.2 **标准实现（高亮的是重点）** ###

除了上面列出的常见的连接器属性，标准的HTTP连接器（BIO，NIO和APR/native）都支持以下属性。

<table> 
 <tbody> 
 <tr> 
 <td style="background:rgb(2,50,100)"> Attribute </td> 
 <td style="background:rgb(2,50,100)"> Description </td> 
 </tr> 
 <tr> 
 <td> acceptCount </td> 
 <td> The maximum queue length for incoming connection requests when all possible request processing threads are in use. Any requests received when the queue is full will be refused. The default value is 100. 当所有可能的请求处理线程都在使用时，传入连接请求的最大队列长度。当队列满时收到的任何请求将被拒绝。默认值是100。 </td> 
 </tr> 
 <tr> 
 <td> acceptorThreadCount </td> 
 <td> The number of threads to be used to accept connections. Increase this value on a multi CPU machine, although you would never really need more than&nbsp;2. Also, with a lot of non keep alive connections, you might want to increase this value as well. Default value is&nbsp;1. 用于接受连接的线程的数量。在一个多CPU的机器上，增加该值，虽然你可能不会真正需要超过2个。此外，有很多非保持活动连接，您可能需要增加这个值。默认值是 1。 </td> 
 </tr> 
 <tr> 
 <td> acceptorThreadPriority </td> 
 <td> The priority of the acceptor threads. The threads used to accept new connections. The default value is&nbsp;5&nbsp;(the value of the&nbsp;java.lang.Thread.NORM_PRIORITY&nbsp;constant). See the JavaDoc for the&nbsp;java.lang.Thread&nbsp;class for more details on what this priority means. 接收器线程的优先级。该线程用来接受新的连接。默认值是5（java.lang.Thread.NORM_PRIORITY常量）。更多这个优先级是什么意思的详细信息，请查看java.lang.Thread的类的JavaDoc 。 </td> 
 </tr> 
 <tr> 
 <td> address </td> 
 <td> For servers with more than one IP address, this attribute specifies which address will be used for listening on the specified port. By default, this port will be used on all IP addresses associated with the server. 对于拥有多个IP地址的服务器，该属性指定哪个地址将被用于在指定端口上监听。默认情况下，该端口将被用于与服务器相关联的所有IP地址。 </td> 
 </tr> 
 <tr> 
 <td> bindOnInit </td> 
 <td> Controls when the socket used by the connector is bound. By default it is bound when the connector is initiated and unbound when the connector is destroyed. If set to&nbsp;false, the socket will be bound when the connector is started and unbound when it is stopped. 控制连接器绑定时套接字的使用。缺省情况，当连接器被启动时套接字被绑定和当连接器被销毁时套接字解除绑定。如果设置为false，连接器启动时套接字被绑定，连接器停止时套接字解除绑定。 </td> 
 </tr> 
 <tr> 
 <td> compressableMimeType </td> 
 <td> The value is a comma separated list of MIME types for which HTTP compression may be used. The default value is&nbsp;text/html,text/xml,text/plain. 该值是一个被用于HTTP压缩的逗号分隔的MIME类型列表。默认值是text / html类型，为text / xml，text / plain。 </td> 
 </tr> 
 <tr> 
 <td> compression </td> 
 <td> The&nbsp;Connector&nbsp;may use HTTP/1.1 GZIP compression in an attempt to save server bandwidth. The acceptable values for the parameter is "off" (disable compression), "on" (allow compression, which causes text data to be compressed), "force" (forces compression in all cases), or a numerical integer value (which is equivalent to "on", but specifies the minimum amount of data before the output is compressed). If the content-length is not known and compression is set to "on" or more aggressive, the output will also be compressed. If not specified, this attribute is set to "off". Note: There is a tradeoff between using compression (saving your bandwidth) and using the sendfile feature (saving your CPU cycles). If the connector supports the sendfile feature, e.g. the NIO connector, using sendfile will take precedence over compression. The symptoms will be that static files greater that 48 Kb will be sent uncompressed. You can turn off sendfile by setting&nbsp;useSendfile&nbsp;attribute of the connector, as documented below, or change the sendfile usage threshold in the configuration of the&nbsp;<a href="http://127.0.0.1:8080/docs/default-servlet.html" rel="nofollow">DefaultServlet</a>&nbsp;in the defaultconf/web.xml&nbsp;or in the&nbsp;web.xml&nbsp;of your web application. 为了节省服务器带宽，连接器可以使用HTTP/1.1 GZIP压缩。可接受的参数的值是“off ”（禁用压缩），“on ”（允许压缩，这会导致文本数据被压缩），“force ”（强制在所有的情况下压缩），或者一个整数值（这是相当于为“on”，但指定了输出之前被压缩的数据最小量）。如果不知道内容长度但被设置为“on”或更积极的压缩，输出的数据也将被压缩。如果没有指定，该属性被设置为“关”。 注意：这是使用压缩（节省您的带宽）和使用sendfile功能（节省你的CPU周期）之间的权衡。如果连接器支持sendfile功能，例如NIO连接，则使用sendfile将优先于压缩。症状是48 KB的静态文件将未压缩就发送。你可以如下文所述通过设置连接器的useSendfile属性来关闭sendfile，或在默认的conf/web.xml或者你的web应用的web.xml中配置DefaultServlet来改变sendfile的使用量阈值。 </td> 
 </tr> 
 <tr> 
 <td> compressionMinSize </td> 
 <td> If&nbsp;compression&nbsp;is set to "on" then this attribute may be used to specify the minimum amount of data before the output is compressed. If not specified, this attribute is defaults to "2048". 如果压缩被设置为“on”，那么该属性可以用于指定在输出之前被压缩的数据的最小量。如果未指定，此属性默认为“2048”。 </td> 
 </tr> 
 <tr> 
 <td> connectionLinger </td> 
 <td> The number of seconds during which the sockets used by this&nbsp;Connector&nbsp;will linger when they are closed. The default value is&nbsp;-1&nbsp;which disables socket linger. 连接器的套接字被关闭时的逗留秒数。如果没有指定，将使用默认的JVM。 </td> 
 </tr> 
 <tr> 
 <td> connectionTimeout </td> 
 <td> The number of milliseconds this&nbsp;Connector&nbsp;will wait, after accepting a connection, for the request URI line to be presented. Use a value of -1 to indicate no (i.e. infinite) timeout. The default value is 60000 (i.e. 60 seconds) but note that the standard server.xml that ships with Tomcat sets this to 20000 (i.e. 20 seconds). UnlessdisableUploadTimeout&nbsp;is set to&nbsp;false, this timeout will also be used when reading the request body (if any). 在将提交的请求URI行呈现之后，连接器将等待接受连接的毫秒数。使用值-1表示没有超时（即无限）。默认值是60000（60秒），但请注意，Tomcat的标准server.xml中，设置为20000（即20秒）。 </td> 
 </tr> 
 <tr> 
 <td> connectionUploadTimeout </td> 
 <td> Specifies the timeout, in milliseconds, to use while a data upload is in progress. This only takes effect if&nbsp;disableUploadTimeout&nbsp;is set to&nbsp;false. 上传数据过程中，指定的以毫秒为单位超时时间。只有在设置disableUploadTimeout为false有效。 </td> 
 </tr> 
 <tr> 
 <td> disableUploadTimeout </td> 
 <td> This flag allows the servlet container to use a different, usually longer connection timeout during data upload. If not specified, this attribute is set to&nbsp;true&nbsp;which disables this longer timeout. 此标志允许servlet容器在数据上传时使用不同的连接超时，通常较长。如果没有指定，该属性被设置为true，禁用上传超时。 </td> 
 </tr> 
 <tr> 
 <td> executor </td> 
 <td> A reference to the name in an&nbsp;<a href="http://127.0.0.1:8080/docs/config/executor.html" rel="nofollow">Executor</a>&nbsp;element. If this attribute is set, and the named executor exists, the connector will use the executor, and all the other thread attributes will be ignored. Note that if a shared executor is not specified for a connector then the connector will use a private, internal executor to provide the thread pool. 指向Executor元素的引用。如果这个属性被设置，并且被命名的executor存在，连接器将使用这个executor，而其他所有线程相关属性将被忽略。请注意共享的executor如果没有指定到一个连接器，则该连接器将使用一个私有的，内部的executor来提供线程池。 </td> 
 </tr> 
 <tr> 
 <td> executorTerminationTimeoutMillis </td> 
 <td> The time that the private internal executor will wait for request processing threads to terminate before continuing with the process of stopping the connector. If not set, the default is&nbsp;0&nbsp;(zero) for the BIO connector and&nbsp;5000&nbsp;(5 seconds) for the NIO and APR/native connectors. </td> 
 </tr> 
 <tr> 
 <td> keepAliveTimeout </td> 
 <td> The number of milliseconds this&nbsp;Connector&nbsp;will wait for another HTTP request before closing the connection. The default value is to use the value that has been set for theconnectionTimeout&nbsp;attribute. Use a value of -1 to indicate no (i.e. infinite) timeout. 此连接器在关闭连接之前将等待另一个HTTP请求的毫秒数。默认值是使用已设置的connectionTimeout属性的值。使用值-1表示没有超时（即无限）。 </td> 
 </tr> 
 <tr> 
 <td> maxConnections </td> 
 <td> The maximum number of connections that the server will accept and process at any given time. When this number has been reached, the server will accept, but not process, one further connection. This additional connection be blocked until the number of connections being processed falls below&nbsp;maxConnections&nbsp;at which point the server will start accepting and processing new connections again. Note that once the limit has been reached, the operating system may still accept connections based on the&nbsp;acceptCount&nbsp;setting. The default value varies by connector type. For BIO the default is the value of&nbsp;maxThreads&nbsp;unless an<a href="http://127.0.0.1:8080/docs/config/executor.html" rel="nofollow">Executor</a>&nbsp;is used in which case the default will be the value of maxThreads from the executor. For NIO the default is&nbsp;10000. For APR/native, the default is&nbsp;8192. Note that for APR/native on Windows, the configured value will be reduced to the highest multiple of 1024 that is less than or equal to maxConnections. This is done for performance reasons. If set to a value of -1, the maxConnections feature is disabled and connections are not counted. 在任何给定的时间服务器接受并处理的最大连接数。当这个数字已经达到了，服务器将不会接受任何连接，直到连接的数量降到低于此值。基于acceptCount的设置，操作系统可能仍然接受连接。默认值根据不同的连接器类型而不同。对于BIO，默认的是maxThreads的值，除非使用了Executor，在这种情况下默认值是executor的maxThreads值 。对于NIO的默认值是10000。APR /native的默认值是8192。 需要注意的是Windows系统的APR/native，所配置的值将减少到小于或等于maxConnections的1024的倍数的最大值。这样做是出于性能方面的考虑。 如果设置的值-1，maxConnections功能被禁用，而且连接数将不做计算。 </td> 
 </tr> 
 <tr> 
 <td> maxExtensionSize </td> 
 <td> Limits the total length of chunk extensions in chunked HTTP requests. If the value is&nbsp;-1, no limit will be imposed. If not specified, the default value of&nbsp;8192&nbsp;will be used. </td> 
 </tr> 
 <tr> 
 <td> maxHttpHeaderSize </td> 
 <td> The maximum size of the request and response HTTP header, specified in bytes. If not specified, this attribute is set to 8192 (8 KB). 请求和响应的HTTP头的（以字节为单位的）最大尺寸。如果没有指定，该属性被设置为8192（8 KB）。 </td> 
 </tr> 
 <tr> 
 <td> maxKeepAliveRequests </td> 
 <td> The maximum number of HTTP requests which can be pipelined until the connection is closed by the server. Setting this attribute to 1 will disable HTTP/1.0 keep-alive, as well as HTTP/1.1 keep-alive and pipelining. Setting this to -1 will allow an unlimited amount of pipelined or keep-alive HTTP requests. If not specified, this attribute is set to 100. HTTP请求最大长连接个数。将此属性设置为1，将禁用HTTP/1.0、以及HTTP/1.1的长连接。设置为-1，不禁用。如果没有指定，该属性被设置为100。 </td> 
 </tr> 
 <tr> 
 <td> maxSwallowSize </td> 
 <td> The maximum number of request body bytes (excluding transfer encoding overhead) that will be swallowed by Tomcat for an aborted upload. An aborted upload is when Tomcat knows that the request body is going to be ignored but the client still sends it. If Tomcat does not swallow the body the client is unlikely to see the response. If not specified the default of 2097152 (2 megabytes) will be used. A value of less than zero indicates that no limit should be enforced. </td> 
 </tr> 
 <tr> 
 <td> maxThreads </td> 
 <td> The maximum number of request processing threads to be created by this&nbsp;Connector, which therefore determines the maximum number of simultaneous requests that can be handled. If not specified, this attribute is set to 200. If an executor is associated with this connector, this attribute is ignored as the connector will execute tasks using the executor rather than an internal thread pool. 最多同时处理的连接数，Tomcat使用线程来处理接收的每个请求。这个值表示Tomcat可创建的最大的线程数。如果没有指定，该属性被设置为200。如果使用了execute将忽略此连接器的该属性，连接器将使用execute，而不是一个内部线程池来处理请求。 </td> 
 </tr> 
 <tr> 
 <td> maxTrailerSize </td> 
 <td> Limits the total length of trailing headers in the last chunk of a chunked HTTP request. If the value is&nbsp;-1, no limit will be imposed. If not specified, the default value of&nbsp;8192will be used. 限制一个分块的HTTP请求中的最后一个块的尾随标头的总长度。如果该值是-1，没有限制的被强加。如果没有指定，默认值是8192。 </td> 
 </tr> 
 <tr> 
 <td> minSpareThreads </td> 
 <td> The minimum number of threads always kept running. If not specified, the default of&nbsp;10&nbsp;is used. 始终保持运行最小线程数。如果没有指定，则默认为10。 </td> 
 </tr> 
 <tr> 
 <td> noCompressionUserAgents </td> 
 <td> The value is a regular expression (using&nbsp;java.util.regex) matching the&nbsp;user-agent&nbsp;header of HTTP clients for which compression should not be used, because these clients, although they do advertise support for the feature, have a broken implementation. The default value is an empty String (regexp matching disabled). 该值是一个正则表达式（使用java.util.regex），匹配不应该使用压缩的HTTP客户端的用户代理标头。因为这些客户端，虽然他们宣称支持压缩功能，但实现不完整。默认值是一个空字符串（正则表达式匹配禁用）。 </td> 
 </tr> 
 <tr> 
 <td> processorCache </td> 
 <td> The protocol handler caches Processor objects to speed up performance. This setting dictates how many of these objects get cached.&nbsp;-1&nbsp;means unlimited, default is&nbsp;200. If not using Servlet 3.0 asynchronous processing, a good default is to use the same as the maxThreads setting. If using Servlet 3.0 asynchronous processing, a good default is to use the larger of maxThreads and the maximum number of expected concurrent requests (synchronous and asynchronous). 协议处理器缓存Processor对象以提高性能。此设置规定了这些对象有多少能得到缓存。-1意味着无限制，默认为200。如果不使用Servlet 3.0的异步处理，一个好的默认是使用maxThreads设置。如果使用Servlet 3.0的异步处理，一个好的默认是使用maxThreads和最大预期的并发请求（同步和异步）的最大值中的较大值。 </td> 
 </tr> 
 <tr> 
 <td> restrictedUserAgents </td> 
 <td> The value is a regular expression (using&nbsp;java.util.regex) matching the&nbsp;user-agent&nbsp;header of HTTP clients for which HTTP/1.1 or HTTP/1.0 keep alive should not be used, even if the clients advertise support for these features. The default value is an empty String (regexp matching disabled). 该值是一个正则表达式（使用java.util.regex），匹配用户代理头的HTTP浏览器将不能使用HTTP/1.1或HTTP/1.0长连接，即使该浏览器宣称支持这些功能的。默认值是一个空字符串（正则表达式匹配禁用）。 </td> 
 </tr> 
 <tr> 
 <td> server </td> 
 <td> Overrides the Server header for the http response. If set, the value for this attribute overrides the Tomcat default and any Server header set by a web application. If not set, any value specified by the application is used. If the application does not specify a value then&nbsp;Apache-Coyote/1.1&nbsp;is used. Unless you are paranoid, you won't need this feature. 覆盖服务器的HTTP响应头。如果设置了这个属性的值将覆盖Web应用程序设置的Tomcat的默认头和任何服务器头。如果没有设置，应用程序指定的任何值将被使用。如果应用程序没有指定一个值，那么Apache-Coyote/1.1将被使用。除非你是偏执狂，你将不再需要此功能。 </td> 
 </tr> 
 <tr> 
 <td> socketBuffer </td> 
 <td> The size (in bytes) of the buffer to be provided for socket output buffering. -1 can be specified to disable the use of a buffer. By default, a buffers of 9000 bytes will be used. 为套接字输出缓冲而提供的缓冲区的大小（以字节为单位）。-1可以被指定来禁止使用的缓冲区。默认情况下，一个9000个字节的缓冲区将被使用。 </td> 
 </tr> 
 <tr> 
 <td> SSLEnabled </td> 
 <td> Use this attribute to enable SSL traffic on a connector. To turn on SSL handshake/encryption/decryption on a connector set this value to&nbsp;true. The default value is&nbsp;false. When turning this value&nbsp;true&nbsp;you will want to set the&nbsp;scheme&nbsp;and the&nbsp;secureattributes as well to pass the correct&nbsp;request.getScheme()&nbsp;and&nbsp;request.isSecure()&nbsp;values to the servlets See&nbsp;<a rel="nofollow">SSL Support</a>&nbsp;for more information. 在连接器上使用此属性来启用SSL加密传输。如果要打开SSL握手/加密/解密，请设置true。默认值是false。当设置这个值为true时，为了传递正确的request.getScheme（）和 request.isSecure（）到servlets，你需要设置scheme和secure属性。更多信息请查看SSL支持。 </td> 
 </tr> 
 <tr> 
 <td> tcpNoDelay </td> 
 <td> If set to&nbsp;true, the TCP_NO_DELAY option will be set on the server socket, which improves performance under most circumstances. This is set to&nbsp;true&nbsp;by default. 如果设置为true，TCP_NO_DELAY选项将被设置在服务器上的套接字上，在大多数情况下，这样可以提高性能。默认设置为true。 </td> 
 </tr> 
 <tr> 
 <td> threadPriority </td> 
 <td> The priority of the request processing threads within the JVM. The default value is&nbsp;5(the value of the&nbsp;java.lang.Thread.NORM_PRIORITY&nbsp;constant). See the JavaDoc for thejava.lang.Thread&nbsp;class for more details on what this priority means. 在JVM中请求处理线程的优先级。默认值是5（java.lang.Thread.NORM_PRIORITY常量值）。关于优先级的更多详细信息，请查看java.lang.Thread的类的JavaDoc 。 </td> 
 </tr> 
 <tr> 
 <td> upgradeAsyncWriteBufferSize </td> 
 <td> The default size of the buffer to allocate to for asynchronous writes that can not be completed in a single operation. Data that can't be written immediately will be stored in this buffer until it can be written. If more data needs to be stored than space is available in the buffer than the size of the buffer will be increased for the duration of the write. If not specified the default value of 8192 will be used. </td> 
 </tr> 
 </tbody> 
</table>

### 3.4.3 **NIO的具体配置** ###

### 3.4.4 **最佳实践** ###

![Image 1][]

# 4. **禁用AJP连接器** #

AJP（Apache JServer Protocol）

AJPv13协议是面向包的。WEB服务器和Servlet容器通过TCP连接来交互；为了节省SOCKET创建的昂贵代价，WEB服务器会尝试维护一个永久TCP连接到servlet容器，并且在多个请求和响应周期过程会重用连接。

![Image 1][]

我们一般是使用Nginx+tomcat的架构，所以用不着AJP协议，所以把AJP连接器禁用。

![Image 1][]

# 5. **JVM参数的优化** #

适当调整Tomcat的运行JVM参数可以提升整体性能。

## 5.1**JVM内存模型** ##

![Image 1][]

## 5.2. **JVM参数** ##

修改文件：bin/catalina.sh

JAVA\_OPTS="-Dfile.encoding=UTF-8 -server -Xms1024m -Xmx1024m -XX:NewSize=512m -XX:MaxNewSize=512m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:NewRatio=2 -XX:MaxTenuringThreshold=50 -XX:+DisableExplicitGC"

参数说明：

1、 file.encoding 默认文件编码

2、 -Xmx1024m  设置JVM最大可用内存为1024MB

3、 -Xms1024m  设置JVM最小内存为1024m。此值可以设置与\-Xmx相同，以避免每次垃圾回收完成后JVM重新分配内存。

4、 -XX:NewSize  设置年轻代大小

5、 XX:MaxNewSize 设置最大的年轻代大小

6、 -XX:PermSize  设置永久代大小

7、 -XX:MaxPermSize 设置最大永久代大小

8、 -XX:NewRatio=4:设置年轻代（包括Eden和两个Survivor区）与终身代的比值（除去永久代）。设置为4，则年轻代与终身代所占比值为1：4，年轻代占整个堆栈的1/5

9、 -XX:MaxTenuringThreshold=0：设置垃圾最大年龄，默认为：15。如果设置为0的话，则年轻代对象不经过Survivor区，直接进入年老代。对于年老代比较多的应用，可以提高效率。如果将此值设置为一个较大值，则年轻代对象会在Survivor区进行多次复制，这样可以增加对象再年轻代的存活时间，增加在年轻代即被回收的概论。

10、 -XX:+DisableExplicitGC这个将会忽略手动调用GC的代码使得 System.gc()的调用就会变成一个空调用，完全不会触发任何GC

## 5.3. **在tomcat中设置JVM参数** ##

### 5.3.1. **windows** ###

修改bin/catalina.bat文件设置参数（第一行）

set JAVA\_OPTS=-Dfile.encoding=UTF-8 -server -Xms1024m -Xmx2048m -XX:NewSize=512m -XX:MaxNewSize=1024m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:MaxTenuringThreshold=10 -XX:NewRatio=2 -XX:+DisableExplicitGC

![Image 1][]

### 5.3.2. **linux** ###

修改bin/catalina.sh文件参数（第一行）

JAVA\_OPTS="-Dfile.encoding=UTF-8 -server -Xms1024m -Xmx2048m -XX:NewSize=512m -XX:MaxNewSize=1024m -XX:PermSize=256m -XX:MaxPermSize=256m -XX:MaxTenuringThreshold=10 -XX:NewRatio=2 -XX:+DisableExplicitGC"

![Image 1][]

到此，全部介绍结束，希望对小伙伴们有所帮助。

[http_127.0.0.1_8080]: http://127.0.0.1:8080/
[Image 1]: