CPU 利用率过高定位分析

概述

最近接手的一个项目，服务端的 cpu 利用率一直爆表。不做任何压测，利用率也保持在 200% 左右

 

 

分析

从 top 里面可以看出几个问题
1：负载几乎为 0，可以排除线程过多的问题
2：usr 的 cpu 利用率几乎是 sy 的三倍，初步怀疑代码层面有问题
3：IOwait 几乎没有，可以排除 IO 阻塞的问题

执行 vmstat 1 10

 

1：r+b 的队列不长
2：bi+bo 几乎为 0
3：in+cs 也不高
4：wa 几乎为 0

 

执行 mpstat -P ALL 1
1：逻辑 cpu 的利用率分布均匀
2：逻辑 cpu 的 usr 利用率明显高于 sys，下一步需要去定位线程日志

jstack 6964 | grep 1b5d -A 200

"DubboSaveRegistryCache-thread-1" #45 daemon prio=5 os_prio=0 tid=0x00007f3c24fcc000 nid=0x6fba runnable [0x00007f3c216c1000]
   java.lang.Thread.State: RUNNABLE
    at java.lang.String.substring(String.java:1933)
    at java.io.File.getName(File.java:456)
    at java.io.UnixFileSystem.getBooleanAttributes(UnixFileSystem.java:243)
    at java.io.File.exists(File.java:819)
    at com.alibaba.dubbo.registry.support.AbstractRegistry.doSaveProperties(AbstractRegistry.java:184)
    at com.alibaba.dubbo.registry.support.AbstractRegistry$SaveProperties.run(AbstractRegistry.java:150)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

"ZkClient-EventThread-42-10.10.1.16:2181,10.10.1.17:2181,10.10.1.18:2181" #42 daemon prio=5 os_prio=0 tid=0x00007f3c24fff000 nid=0x6fae waiting on condition [0x00007f3c219c4000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38ff950> (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 org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:67)

"DubboRegistryFailedRetryTimer-thread-1" #41 daemon prio=5 os_prio=0 tid=0x00007f3c24ffc000 nid=0x6fad waiting on condition [0x00007f3c21ac5000]
   java.lang.Thread.State: TIMED_WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38fdc50> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    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)

"DubboSaveRegistryCache-thread-1" #38 daemon prio=5 os_prio=0 tid=0x00007f3c24ff9000 nid=0x6fa3 waiting on condition [0x00007f3c21fc8000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38ffd88> (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)

"localhost-startStop-1-EventThread" #37 daemon prio=5 os_prio=0 tid=0x00007f3c24ff8000 nid=0x6fa2 waiting on condition [0x00007f3c220c9000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c39003b0> (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 org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:494)

"localhost-startStop-1-SendThread(10.200.2.1:2181)" #36 daemon prio=5 os_prio=0 tid=0x00007f3c24fdc000 nid=0x6fa1 runnable [0x00007f3c221ca000]
   java.lang.Thread.State: RUNNABLE
    at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
    at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
    at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:79)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000000c390f150> (a sun.nio.ch.Util$2)
    - locked <0x00000000c390f140> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000000c390ecd8> (a sun.nio.ch.EPollSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
    at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:349)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)

"ZkClient-EventThread-35-10.200.2.1:2181" #35 daemon prio=5 os_prio=0 tid=0x00007f3c24fda800 nid=0x6fa0 waiting on condition [0x00007f3c222cb000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c390d1d0> (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 org.I0Itec.zkclient.ZkEventThread.run(ZkEventThread.java:67)

"DubboRegistryFailedRetryTimer-thread-1" #34 daemon prio=5 os_prio=0 tid=0x00007f3c24fd9800 nid=0x6f9f waiting on condition [0x00007f3c223cc000]
   java.lang.Thread.State: TIMED_WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c3909788> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    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)

"dubbo-remoting-client-heartbeat-thread-2" #33 daemon prio=5 os_prio=0 tid=0x00007f3c24fc1800 nid=0x6f9e waiting on condition [0x00007f3c224cd000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38fa2b0> (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.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    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)

"DubboClientReconnectTimer-thread-2" #31 daemon prio=5 os_prio=0 tid=0x00007f3c24fb1800 nid=0x6f9c waiting on condition [0x00007f3c226cf000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38ced20> (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.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    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)

"Druid-ConnectionPool-Destory-645490863" #16 daemon prio=5 os_prio=0 tid=0x00007f48bcb8d800 nid=0x1b58 waiting on condition [0x00007f48d5b49000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
    at java.lang.Thread.sleep(Native Method)
    at com.alibaba.druid.pool.DruidDataSource$DestroyConnectionThread.run(DruidDataSource.java:1724)

"Druid-ConnectionPool-Create-645490863" #15 daemon prio=5 os_prio=0 tid=0x00007f48bcb90800 nid=0x1b57 waiting on condition [0x00007f48f0160000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c3b35050> (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 com.alibaba.druid.pool.DruidDataSource$CreateConnectionThread.run(DruidDataSource.java:1634)

"dubbo-remoting-client-heartbeat-thread-1" #30 daemon prio=5 os_prio=0 tid=0x00007f3c24f1b000 nid=0x6f9b waiting on condition [0x00007f3c227d0000]
   java.lang.Thread.State: TIMED_WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38fa2b0> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    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)

"localhost-startStop-1-EventThread" #20 daemon prio=5 os_prio=0 tid=0x00007f48bcd84000 nid=0x1b5c waiting on condition [0x00007f48d5345000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c3aac968> (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 org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:494)

"localhost-startStop-1-SendThread(10.200.4.56:2181)" #19 daemon prio=5 os_prio=0 tid=0x00007f48bcd68000 nid=0x1b5b runnable [0x00007f48d5446000]
   java.lang.Thread.State: RUNNABLE
    at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
    at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
    at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:79)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000000c3b2ee38> (a sun.nio.ch.Util$2)
    - locked <0x00000000c3b2ee28> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000000c3b2e9c0> (a sun.nio.ch.EPollSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
    at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:349)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1081)

"Hashed wheel timer #1" #25 prio=5 os_prio=0 tid=0x00007f3c54001800 nid=0x6f99 waiting on condition [0x00007f3c229d2000]
   java.lang.Thread.State: TIMED_WAITING (sleeping)
    at java.lang.Thread.sleep(Native Method)
    at org.jboss.netty.util.HashedWheelTimer$Worker.waitForNextTick(HashedWheelTimer.java:503)
    at org.jboss.netty.util.HashedWheelTimer$Worker.run(HashedWheelTimer.java:401)
    at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
    at java.lang.Thread.run(Thread.java:745)

"DubboClientReconnectTimer-thread-1" #28 daemon prio=5 os_prio=0 tid=0x00007f3c24f13000 nid=0x6f98 runnable [0x00007f3c22ad3000]
   java.lang.Thread.State: TIMED_WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000c38ced20> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1093)
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
    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)

"New I/O boss #4" #26 daemon prio=5 os_prio=0 tid=0x00007f3c24ee1800 nid=0x6f97 runnable [0x00007f3c22bd4000]
   java.lang.Thread.State: RUNNABLE
    at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
    at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
    at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:79)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000000c37d1bf0> (a sun.nio.ch.Util$2)
    - locked <0x00000000c37d1be0> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000000c37d1998> (a sun.nio.ch.EPollSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
    at org.jboss.netty.channel.socket.nio.SelectorUtil.select(SelectorUtil.java:68)
    at org.jboss.netty.channel.socket.nio.AbstractNioSelector.select(AbstractNioSelector.java:409)
    at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:206)
    at org.jboss.netty.channel.socket.nio.NioClientBoss.run(NioClientBoss.java:42)
    at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
    at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

"New I/O worker #3" #24 daemon prio=5 os_prio=0 tid=0x00007f3c24e79800 nid=0x6f96 runnable [0x00007f3c22cd5000]
   java.lang.Thread.State: RUNNABLE
    at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
    at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
    at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:79)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000000c38ce410> (a sun.nio.ch.Util$2)
    - locked <0x00000000c38ce400> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000000c38cba08> (a sun.nio.ch.EPollSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)
    at org.jboss.netty.channel.socket.nio.SelectorUtil.select(SelectorUtil.java:68)
    at org.jboss.netty.channel.socket.nio.AbstractNioSelector.select(AbstractNioSelector.java:409)
    at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:206)
    at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:90)
    at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178)
    at org.jboss.netty.util.ThreadRenamingRunnable.run(ThreadRenamingRunnable.java:108)
    at org.jboss.netty.util.internal.DeadLockProofWorker$1.run(DeadLockProofWorker.java:42)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

"New I/O worker #2" #23 daemon prio=5 os_prio=0 tid=0x00007f3c24e77800 nid=0x6f95 runnable [0x00007f3c22dd6000]
   java.lang.Thread.State: RUNNABLE
    at sun.nio.ch.EPollArrayWrapper.epollWait(Native Method)
    at sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:269)
    at sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:79)
    at sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:86)
    - locked <0x00000000c38cb438> (a sun.nio.ch.Util$2)
    - locked <0x00000000c38cb428> (a java.util.Collections$UnmodifiableSet)
    - locked <0x00000000c38b8be0> (a sun.nio.ch.EPollSelectorImpl)
    at sun.nio.ch.SelectorImpl.select(SelectorImpl.java:97)

中间的 TIMED_WAITING (parking) 需要特别关注
从日志中可以看出我们的进程有哪些长期处于 parking，大致下面这几块
等待 zk 连接
等待 dubbo 注册
localhost-startStop-1-EventThread 卡死
dubbo-remoting-client-heartbeat（dubbo 心跳）
ruid-ConnectionPool-Create(数据池连接)

zk 连接，dubbo 注册，dubbo 心跳，数据池连接这些应该都是网络问题，需要找运维确认一下

localhost-startStop-1-EventThread 这个就比较有意思了。
网上查了一下，localhost-startStop-1 卡死是因为熵池不够大。熵池这玩意到底是什么，说实话我从来没有听说过。这里给出一些解决方案
先查看熵池大小： cat /proc/sys/kernel/random/entropy_avail

 

再看一下 cpu 是否支持熵池

 

接下来要开启熵服务
apt-get install rng-tools 安装 rngd 服务（熵服务）
service rng-tools start 启动服务

 

来源：https://testerhome.com/articles/24744