Tomcat maxThreads maxConnections acceptCount参数说明

首先看官网对这个三个参数的说明:
http://tomcat.apache.org/tomcat-7.0-doc/config/http.html

Attribute Description
acceptCount 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.
maxConnections 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 maxConnections 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 acceptCount setting. The default value varies by connector type. For BIO the default is the value of maxThreads unless an Executor is used in which case the default will be the value of maxThreads from the executor. For NIO the default is 10000. For APR/native, the default is 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.
maxThreads The maximum number of request processing threads to be created by this 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. Note that if an executor is configured any value set for this attribute will be recorded correctly but it will be reported (e.g. via JMX) as -1 to make clear that it is not used.

用httpClient作为客户端对不同配置分别发10个请求,服务端死循环让请求一直没有返回,然后查看连接情况。
注意,在用httpClient发送请求的时候一定要设置这个参数,否则默认最多只能发送两个并发请求。
// Increase default max connection per route to 20
cm.setDefaultMaxPerRoute(20);

一##

tomcat配置:
<Connector port="8090" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" maxConnections="3" maxThreads="2" acceptCount="4" />

连接情况7个为ESTABLISHED,3个为SYN_SENT:

netstat -an | grep 8090##

tcp4 158 0 127.0.0.1.8090 127.0.0.1.61515 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61514 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61513 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61512 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61511 ESTABLISHED
tcp4 0 0 127.0.0.1.8090 127.0.0.1.61510 ESTABLISHED
tcp4 0 0 127.0.0.1.8090 127.0.0.1.61509 ESTABLISHED
tcp4 0 0 127.0.0.1.61510 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61511 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61512 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61513 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61514 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61515 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61517 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61509 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61518 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61516 127.0.0.1.8090 SYN_SENT
tcp46 0 0 *.8090 . LISTEN

二##

tomcat配置:
<Connector port="8090" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" maxConnections="5" maxThreads="2" acceptCount="1" />

连接情况6个为ESTABLISHED,4个为SYN_SENT:

netstat -an | grep 8090#

tcp4 0 0 127.0.0.1.61672 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61671 127.0.0.1.8090 SYN_SENT
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61663 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61670 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61669 ESTABLISHED
tcp4 158 0 127.0.0.1.8090 127.0.0.1.61668 ESTABLISHED
tcp4 0 0 127.0.0.1.8090 127.0.0.1.61662 ESTABLISHED
tcp4 0 0 127.0.0.1.8090 127.0.0.1.61661 ESTABLISHED
tcp4 0 0 127.0.0.1.61669 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61668 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61661 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61667 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61662 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61663 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61664 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61670 127.0.0.1.8090 ESTABLISHED
tcp46 0 0 *.8090 . LISTEN

三##

tomcat配置:
<Connector port="8090" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" maxConnections="0" maxThreads="2" acceptCount="1" />

连接情况3个为ESTABLISHED,7个为SYN_SENT:

netstat -an | grep 8090#

tcp4 158 0 127.0.0.1.8090 127.0.0.1.61748 ESTABLISHED
tcp4 0 0 127.0.0.1.8090 127.0.0.1.61743 ESTABLISHED
tcp4 0 0 127.0.0.1.8090 127.0.0.1.61742 ESTABLISHED
tcp4 0 0 127.0.0.1.61744 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61748 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61743 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61742 127.0.0.1.8090 ESTABLISHED
tcp4 0 0 127.0.0.1.61749 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61747 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61750 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61751 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61745 127.0.0.1.8090 SYN_SENT
tcp4 0 0 127.0.0.1.61746 127.0.0.1.8090 SYN_SENT
tcp46 0 0 *.8090 . LISTEN

四##

tomcat配置:
<Connector port="8090" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" maxConnections="0" maxThreads="2" acceptCount="0" />

这次改为发了101个请求,结果连接状态都为ESTABLISHED。

做这几个实验,主要是读文档的时候没有弄清楚acceptCount是当maxThreads达到最大值时起作用还是当maxConnections达到最大值时起作用。

最后通过以上得出结论:##

1)tomcat可接受最大连接数为maxConnections+acceptCount;
2)当maxConnections="0",maxConnections的值等于maxThreads;
3)当acceptCount="0",acceptCount的值不是默认的100,具体多少取决操作系统的配置(后面看下tomcat的源码)。
4)maxThreads就是真正同时在处理请求的业务线程(可以通过看stack日志确定)。

其实上面这些通过看tomcat的源码最为准确了,做这个测试主要是为了打发下时间。另外对tcp的连接状态不太清楚的可以看下tcp/ip详解的第18章。

最后编辑于
©著作权归作者所有,转载或内容合作请联系作者
  • 序言:七十年代末,一起剥皮案震惊了整个滨河市,随后出现的几起案子,更是在滨河造成了极大的恐慌,老刑警刘岩,带你破解...
    沈念sama阅读 148,637评论 1 318
  • 序言:滨河连续发生了三起死亡事件,死亡现场离奇诡异,居然都是意外死亡,警方通过查阅死者的电脑和手机,发现死者居然都...
    沈念sama阅读 63,443评论 1 266
  • 文/潘晓璐 我一进店门,熙熙楼的掌柜王于贵愁眉苦脸地迎上来,“玉大人,你说我怎么就摊上这事。” “怎么了?”我有些...
    开封第一讲书人阅读 99,164评论 0 218
  • 文/不坏的土叔 我叫张陵,是天一观的道长。 经常有香客问我,道长,这世上最难降的妖魔是什么? 我笑而不...
    开封第一讲书人阅读 42,075评论 0 188
  • 正文 为了忘掉前任,我火速办了婚礼,结果婚礼上,老公的妹妹穿的比我还像新娘。我一直安慰自己,他们只是感情好,可当我...
    茶点故事阅读 50,080评论 1 266
  • 文/花漫 我一把揭开白布。 她就那样静静地躺着,像睡着了一般。 火红的嫁衣衬着肌肤如雪。 梳的纹丝不乱的头发上,一...
    开封第一讲书人阅读 39,365评论 1 184
  • 那天,我揣着相机与录音,去河边找鬼。 笑死,一个胖子当着我的面吹牛,可吹牛的内容都是我干的。 我是一名探鬼主播,决...
    沈念sama阅读 30,901评论 2 283
  • 文/苍兰香墨 我猛地睁开眼,长吁一口气:“原来是场噩梦啊……” “哼!你这毒妇竟也来了?” 一声冷哼从身侧响起,我...
    开封第一讲书人阅读 29,649评论 0 176
  • 序言:老挝万荣一对情侣失踪,失踪者是张志新(化名)和其女友刘颖,没想到半个月后,有当地人在树林里发现了一具尸体,经...
    沈念sama阅读 33,122评论 0 223
  • 正文 独居荒郊野岭守林人离奇死亡,尸身上长有42处带血的脓包…… 初始之章·张勋 以下内容为张勋视角 年9月15日...
    茶点故事阅读 29,734评论 2 225
  • 正文 我和宋清朗相恋三年,在试婚纱的时候发现自己被绿了。 大学时的朋友给我发了我未婚夫和他白月光在一起吃饭的照片。...
    茶点故事阅读 31,093评论 1 236
  • 序言:一个原本活蹦乱跳的男人离奇死亡,死状恐怖,灵堂内的尸体忽然破棺而出,到底是诈尸还是另有隐情,我是刑警宁泽,带...
    沈念sama阅读 27,548评论 2 222
  • 正文 年R本政府宣布,位于F岛的核电站,受9级特大地震影响,放射性物质发生泄漏。R本人自食恶果不足惜,却给世界环境...
    茶点故事阅读 32,028评论 3 216
  • 文/蒙蒙 一、第九天 我趴在偏房一处隐蔽的房顶上张望。 院中可真热闹,春花似锦、人声如沸。这庄子的主人今日做“春日...
    开封第一讲书人阅读 25,765评论 0 9
  • 文/苍兰香墨 我抬头看了看天上的太阳。三九已至,却和暖如春,着一层夹袄步出监牢的瞬间,已是汗流浃背。 一阵脚步声响...
    开封第一讲书人阅读 26,291评论 0 178
  • 我被黑心中介骗来泰国打工, 没想到刚下飞机就差点儿被人妖公主榨干…… 1. 我叫王不留,地道东北人。 一个月前我还...
    沈念sama阅读 34,162评论 2 239
  • 正文 我出身青楼,却偏偏与公主长得像,于是被迫代替她去往敌国和亲。 传闻我的和亲对象是个残疾皇子,可洞房花烛夜当晚...
    茶点故事阅读 34,293评论 2 242

推荐阅读更多精彩内容