Tomcat8 配置 "maxThreads" 不起作用
Tomcat8 configuration "maxThreads" does not work
您可以在下方 server.xml 中找到 maxThreads 限制为 350。
然后，我使用下面的命令来检查当前 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"检查当前线程数是1429，它大于maxThreads限制350。
所以，我的问题是为什么配置 maxThreads 不起作用，以及如何检查 运行 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 "%r" %s %b" />
</Host>
</Engine>
</Service>
</Server>
更新
谢谢@adamM，我只是用 jstack 检查当前 运行 个线程，发现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)
maxThreads 配置servlet 请求线程数（响应请求的线程）。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。看看这个post:
Get a List of all Threads currently running in Java
JVM 中的线程会做很多事情。而不是使用 ps -eL <java_pid> | wc -l、
使用 ps -eL <java_pid> 从列表中获取不同的 运行 线程，然后像下面的示例一样尝试，
ps -eL <java_pid> | grep "/usr/lib/jvm/java-8-oracle/bin/java" | wc -l
ps -eL <java_pid> | grep "/usr/sbin/mysqld" | wc -l
ps -eL <java_pid> | grep "/usr/sbin/apache2" | wc -l
您可以在下方 server.xml 中找到 maxThreads 限制为 350。
然后，我使用下面的命令来检查当前 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"检查当前线程数是1429，它大于maxThreads限制350。
所以，我的问题是为什么配置 maxThreads 不起作用，以及如何检查 运行 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 "%r" %s %b" />
</Host>
</Engine>
</Service>
</Server>
更新
谢谢@adamM，我只是用 jstack 检查当前 运行 个线程，发现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)
maxThreads 配置servlet 请求线程数（响应请求的线程）。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。看看这个post:
Get a List of all Threads currently running in Java
JVM 中的线程会做很多事情。而不是使用 ps -eL <java_pid> | wc -l、
使用 ps -eL <java_pid> 从列表中获取不同的 运行 线程，然后像下面的示例一样尝试，
ps -eL <java_pid> | grep "/usr/lib/jvm/java-8-oracle/bin/java" | wc -l
ps -eL <java_pid> | grep "/usr/sbin/mysqld" | wc -l
ps -eL <java_pid> | grep "/usr/sbin/apache2" | wc -l