java - Tomcat8 配置 "maxThreads"不工作

Question

您可以找到 maxThreads限制是 350在下方server.xml .

然后，我使用下面的命令来检查当前的 java pid

$ps uax | grep tomcat
ruyi     25802  0.0  0.0  10436   420 ?        Ss   Oct14   0:00 jsvc.exec -jvm server -java-home /usr/java/jdk1.8.0_51 -user ruyi -pidfile /data/tomcat/logs/catalina-daemon.pid -wait 10 -outfile /data/tomcat/logs/catalina-daemon.out -errfile &1 -classpath /data/tomcat/bin/bootstrap.jar:/data/tomcat/bin/commons-daemon.jar:/data/tomcat/bin/tomcat-juli.jar -Djava.util.logging.config.file=/data/tomcat/conf/logging.properties -server -Djava.net.preferIPv4Stack=true -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Dfile.encoding=UTF8 -Xmx4096m -XX:PermSize=256m -XX:MaxPermSize=512m -Djava.endorsed.dirs= -Dcatalina.base=/data/tomcat -Dcatalina.home=/data/tomcat -Djava.io.tmpdir=/data/tomcat/temp org.apache.catalina.startup.Bootstrap
ruyi     25803  0.6 18.5 9458412 3015712 ?     Sl   Oct14  33:24 jsvc.exec -jvm server -java-home /usr/java/jdk1.8.0_51 -user ruyi -pidfile /data/tomcat/logs/catalina-daemon.pid -wait 10 -outfile /data/tomcat/logs/catalina-daemon.out -errfile &1 -classpath /data/tomcat/bin/bootstrap.jar:/data/tomcat/bin/commons-daemon.jar:/data/tomcat/bin/tomcat-juli.jar -Djava.util.logging.config.file=/data/tomcat/conf/logging.properties -server -Djava.net.preferIPv4Stack=true -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Dfile.encoding=UTF8 -Xmx4096m -XX:PermSize=256m -XX:MaxPermSize=512m -Djava.endorsed.dirs= -Dcatalina.base=/data/tomcat -Dcatalina.home=/data/tomcat -Djava.io.tmpdir=/data/tomcat/temp org.apache.catalina.startup.Bootstrap
ruyi     30257  0.0  0.0 103304   892 pts/1    S+   11:29   0:00 grep tomcat

然后，我使用命令 watch -n 5 -d "ps -eL <java_pid> | wc -l"检查当前线程号是1429 ，比 maxThreads 大限制 350 .

所以，我的问题是为什么要配置maxThreads不起作用，以及如何检查正在运行的 tomcat 的配置(以查看我的配置是否设置正确)。

这是 server.xml

<?xml version='1.0' encoding='utf-8'?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You under the Apache License, Version 2.0
  (the "License"); you may not use this file except in compliance with
  the License.  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
-->
<!-- Note:  A "Server" is not itself a "Container", so you may not
     define subcomponents such as "Valves" at this level.
     Documentation at /docs/config/server.html
 -->
<Server port="8005" shutdown="SHUTDOWN">
  <Listener className="org.apache.catalina.startup.VersionLoggerListener" />
  <!-- Security listener. Documentation at /docs/config/listeners.html
  <Listener className="org.apache.catalina.security.SecurityListener" />
  -->
  <!--APR library loader. Documentation at /docs/apr.html -->
  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />
  <!-- Prevent memory leaks due to use of particular java/javax APIs-->
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <!-- Global JNDI resources
       Documentation at /docs/jndi-resources-howto.html
  -->
  <GlobalNamingResources>
    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users
    -->
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
  </GlobalNamingResources>

  <!-- A "Service" is a collection of one or more "Connectors" that share
       a single "Container" Note:  A "Service" is not itself a "Container",
       so you may not define subcomponents such as "Valves" at this level.
       Documentation at /docs/config/service.html
   -->
  <Service name="Catalina">

    <!--The connectors can use a shared executor, you can define one or more named thread pools-->
    <!--
    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="150" minSpareThreads="4"/>
    -->


    <!-- A "Connector" represents an endpoint by which requests are received
         and responses are returned. Documentation at :
         Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
         Java AJP  Connector: /docs/config/ajp.html
         APR (HTTP/AJP) Connector: /docs/apr.html
         Define a non-SSL/TLS HTTP/1.1 Connector on port 8080
    -->

<Connector executor="tomcatThreadPool" port="8080" protocol="org.apache.coyote.http11.Http11AprProtocol"
maxThreads="350" maxHttpHeaderSize="8192" emptySessionPath="true"
   connectionTimeout="20000" enableLookups="false" maxPostSize="0"
                  redirectPort="8443"  URIEncoding="UTF-8" />
<!--
    <Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" /> -->
    <!-- A "Connector" using the shared thread pool-->
    <!--
    <Connector executor="tomcatThreadPool"
               port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    -->
    <!-- Define a SSL/TLS HTTP/1.1 Connector on port 8443
         This connector uses the NIO implementation that requires the JSSE
         style configuration. When using the APR/native implementation, the
         OpenSSL style configuration is required as described in the APR/native
         documentation -->
    <!--
    <Connector port="8443" protocol="org.apache.coyote.http11.Http11NioProtocol"
               maxThreads="150" SSLEnabled="true" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS" />
    -->

    <!-- Define an AJP 1.3 Connector on port 8009 -->
    <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />


    <!-- An Engine represents the entry point (within Catalina) that processes
         every request.  The Engine implementation for Tomcat stand alone
         analyzes the HTTP headers included with the request, and passes them
         on to the appropriate Host (virtual host).
         Documentation at /docs/config/engine.html -->

    <!-- You should set jvmRoute to support load-balancing via AJP ie :
    <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
    -->
    <Engine name="Catalina" defaultHost="localhost">

      <!--For clustering, please take a look at documentation at:
          /docs/cluster-howto.html  (simple how to)
          /docs/config/cluster.html (reference documentation) -->
      <!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
      -->

      <!-- Use the LockOutRealm to prevent attempts to guess user passwords
           via a brute-force attack -->
      <Realm className="org.apache.catalina.realm.LockOutRealm">
        <!-- This Realm uses the UserDatabase configured in the global JNDI
             resources under the key "UserDatabase".  Any edits
             that are performed against this UserDatabase are immediately
             available for use by the Realm.  -->
        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
               resourceName="UserDatabase"/>
      </Realm>

      <Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">

        <!-- SingleSignOn valve, share authentication between web applications
             Documentation at: /docs/config/valve.html -->
        <!--
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
        -->

        <!-- Access log processes all example.
             Documentation at: /docs/config/valve.html
             Note: The pattern used is equivalent to using pattern="common" -->
        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log" suffix=".txt"
               pattern="%h %l %u %t &quot;%r&quot; %s %b" />

      </Host>
    </Engine>
  </Service>
</Server>

更新

谢谢@adamM，我只用 jstack检查当前正在运行的线程，发现它们中的大部分都在线程下面，有什么想法吗？

 "pool-366-thread-1" #1437 prio=5 os_prio=0 tid=0x00007f55ccbb7000 nid=0x2fa9 waiting on condition [0x00007f55b9ffa000]
    java.lang.Thread.State: WAITING (parking)
         at sun.misc.Unsafe.park(Native Method)
         - parking to wait for  <0x00000006f482a018> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
         at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
         at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
         at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
         at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
         at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
         at java.lang.Thread.run(Thread.java:745)

Answer 1

maxThreads 配置 servlet 请求线程(响应请求的线程)的数量。如果将它设置为 350，那应该是那些线程的限制，但是 JVM 中可能有更多的线程在做其他事情。您可以使用分析器查看 JVM 中线程的名称。线程的名称会让您了解导致这些额外线程的原因。

如果您不想使用探查器，您可以通过获取所有当前线程并打印它们的名称在代码中执行此操作。看看这篇文章:

Get a List of all Threads currently running in Java