如何排查CPU过载过高的问题

本篇内容主要讲解"如何排查CPU过载过高的问题"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"如何排查CPU过载过高的问题"吧!

侦探问题根源

通过top指令发现，当前5511的线程cup和内存的使用率过高：

top5511 root      20   0 16.841g 6.088g   5584 S  47.0 39.2   4011:41 java9550 root      20   0 2516200  67892   2436 S   0.7  0.4 204:20.40 java21271 root      20   0 11.579g 0.987g   5056 S   0.7  6.4  46:29.88 java13 root      20   0       0      0      0 S   0.3  0.0   0:35.21 ksoftirqd/12128 root      20   0  9.833g 1.273g   6656 S   0.3  8.2  33:48.35 java 29464 root      20   0 11.578g 1.030g   5448 S   0.3  6.6  31:42.67 java 31721 root      20   0  157744   2264   1544 R   0.3  0.0   0:00.32 top

查询当前java进程详情，利用 jinfo pid 5511

Attaching to process ID 5511, please wait...Debugger attached successfully.Server compiler detected.JVM version is 25.151-b12Java System Properties:java.runtime.name = Java(TM) SE Runtime Environmentjava.vm.version = 25.151-b12sun.boot.library.path = /usr/local/java/jre/lib/amd64java.vendor.url = http://java.oracle.com/java.vm.vendor = Oracle Corporationpath.separator = :file.encoding.pkg = sun.iojava.vm.name = Java HotSpot(TM) 64-Bit Server VMsun.os.patch.level = unknownsun.java.launcher = SUN_STANDARDuser.country = USuser.dir = /mnt/app/bdcenter-base/bdcenter-service-base-1.0-SNAPSHOTjava.vm.specification.name = Java Virtual Machine SpecificationPID = 5511java.runtime.version = 1.8.0_151-b12java.awt.graphicsenv = sun.awt.X11GraphicsEnvironmentos.arch = amd64java.endorsed.dirs = /usr/local/java/jre/lib/endorsedline.separator = java.io.tmpdir = /tmpjava.vm.specification.vendor = Oracle Corporationos.name = Linuxio.netty.noKeySetOptimization = truesun.jnu.encoding = UTF-8java.library.path = /usr/java/packages/lib/amd64:/usr/lib64:/lib64:/lib:/usr/libspring.beaninfo.ignore = truesun.nio.ch.bugLevel = java.specification.name = Java Platform API Specificationjava.class.version = 52.0sun.management.compiler = HotSpot 64-Bit Tiered Compilersos.version = 3.10.0-693.2.2.el7.x86_64user.home = /rootuser.timezone = Asia/Shanghaicatalina.useNaming = falsejava.awt.printerjob = sun.print.PSPrinterJobfile.encoding = UTF-8@appId = bdcenter-service-basejava.specification.version = 1.8io.netty.recycler.maxCapacityPerThread = 0catalina.home = /tmp/tomcat.7050606280722271893.9025user.name = rootjava.class.path = bdcenter-service-base-1.0-SNAPSHOT.jarjava.vm.specification.version = 1.8sun.arch.data.model = 64sun.java.command = bdcenter-service-base-1.0-SNAPSHOT.jar --spring.profiles.active=prod 5java.home = /usr/local/java/jreuser.language = enjava.specification.vendor = Oracle Corporationio.netty.noUnsafe = trueawt.toolkit = sun.awt.X11.XToolkitjava.vm.info = mixed modejava.version = 1.8.0_151java.ext.dirs = /usr/local/java/jre/lib/ext:/usr/java/packages/lib/extsun.boot.class.path = /usr/local/java/jre/lib/resources.jar:/usr/local/java/jre/lib/rt.jar:/usr/local/java/jre/lib/sunrsasign.jar:/usr/local/java/jre/lib/jsse.jar:/usr/local/java/jre/lib/jce.jar:/usr/local/java/jre/lib/charsets.jar:/usr/local/java/jre/lib/jfr.jar:/usr/local/java/jre/classesjava.awt.headless = truejava.vendor = Oracle Corporationcatalina.base = /tmp/tomcat.7050606280722271893.9025file.separator = /java.vendor.url.bug = http://bugreport.sun.com/bugreport/sun.io.unicode.encoding = UnicodeLittlesun.cpu.endian = littlesun.cpu.isalist = VM Flags:Non-default VM flags: -XX:+AggressiveOpts -XX:CICompilerCount=4 -XX:CMSInitiatingOccupancyFraction=75 -XX:+CMSParallelRemarkEnabled -XX:+DisableExplicitGC -XX:InitialHeapSize=6442450944 -XX:MaxDirectMemorySize=1073741824 -XX:MaxHeapSize=6442450944 -XX:MaxNewSize=697892864 -XX:MaxTenuringThreshold=6 -XX:MinHeapDeltaBytes=196608 -XX:NewSize=697892864 -XX:OldPLABSize=16 -XX:OldSize=5744558080 -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:ThreadStackSize=256 -XX:+UseBiasedLocking -XX:+UseCMSCompactAtFullCollection -XX:+UseCMSInitiatingOccupancyOnly -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseConcMarkSweepGC -XX:+UseFastAccessorMethods -XX:+UseParNewGC Command line:  -Xms6G -Xmx6G -XX:MaxPermSize=256M -XX:MaxDirectMemorySize=1G -Xss256k -XX:+AggressiveOpts -XX:+UseBiasedLocking -XX:+UseFastAccessorMethods -XX:+DisableExplicitGC -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled -XX:+UseCMSCompactAtFullCollection -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=75 -XX:CMSInitiatingOccupancyFraction=75 -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCTimeStamps -XX:+PrintGCDetails

Command line 可以看出JVM 用户输入参，对整个jvm的信息进行消息的描述

查看当前gc情况： jstat -gccause 5511

[root@bigdata-service-1:/root]# jstat -gccause 5511 1000  S0     S1     E      O      M     CCS    YGC     YGCT    FGC    FGCT     GCT    LGCC    GCC0.00   8.86  61.50  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure    No GC0.00   8.86  64.31  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure   No GC0.00   8.86  65.04  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure   No GC0.00   8.86  65.17  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure   No GC0.00   8.86  65.26  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure   No GC0.00   8.86  65.26  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure   No GC0.00   8.86  67.80  72.16  95.05  91.62   4577  326.410     8    8.855  335.265 Allocation Failure   No GC

发现新生代频繁的进行gc操【YGC：gc 次数, YGCT： gc时间】，老年的几乎没有gc【FGC：full gc次数，FGCT ：full gc时间】，可能原因是新生代的设计过小，导致新生代频繁gc

查看当前jvm 内存分配：

jmap -heap 5511[root@bigdata-service-1:/root]# jmap -heap 5511Attaching to process ID 5511, please wait...Debugger attached successfully.Server compiler detected.JVM version is 25.151-b12using parallel threads in the new generation.using thread-local object allocation.Concurrent Mark-Sweep GCHeap Configuration:   MinHeapFreeRatio         = 40   MaxHeapFreeRatio         = 70   MaxHeapSize              = 6442450944 (6144.0MB)   NewSize                  = 697892864 (665.5625MB)   MaxNewSize               = 697892864 (665.5625MB)   OldSize                  = 5744558080 (5478.4375MB)   NewRatio                 = 2   SurvivorRatio            = 8   MetaspaceSize            = 21807104 (20.796875MB)   CompressedClassSpaceSize = 1073741824 (1024.0MB)   MaxMetaspaceSize         = 17592186044415 MB   G1HeapRegionSize         = 0 (0.0MB)Heap Usage:New Generation (Eden + 1 Survivor Space):   capacity = 628162560 (599.0625MB)   used     = 210724080 (200.96214294433594MB)   free     = 417438480 (398.10035705566406MB)   33.54610628178795% usedEden Space:   capacity = 558432256 (532.5625MB)   used     = 203572032 (194.14141845703125MB)   free     = 354860224 (338.42108154296875MB)   36.45420367694519% usedFrom Space:   capacity = 69730304 (66.5MB)   used     = 7152048 (6.8207244873046875MB)   free     = 62578256 (59.67927551269531MB)   10.256728552337876% usedTo Space:   capacity = 69730304 (66.5MB)   used     = 0 (0.0MB)   free     = 69730304 (66.5MB)   0.0% usedconcurrent mark-sweep generation:   capacity = 5744558080 (5478.4375MB)   used     = 4145940376 (3953.876853942871MB)   free     = 1598617704 (1524.560646057129MB)   72.17161561016022% used32720 interned Strings occupying 4008568 bytes.

• 从JVM的分配可以看出，新生代分配：capacity = 628162560 (599.0625MB)，Eden Space：capacity = 558432256 (532.5625MB)，老年代分配：capacity = 5744558080 (5478.4375MB)。从数据分析出，新生代设计过小，导致新生代频繁gc。

• 其次，新生代设计过小，导致大对象无法分配，直接分配到老年代。导致老年代空间占用过大，从而占用整个系统内存空间。可能导致其他服务内存不足。

线上手动GC，查看GC后的JVM详情信息:

[root@bigdata-service-1:/root]# jmap -histo:live 5511日志过大.....[root@bigdata-service-1:/root]# jstat -gc 5511 1000 S0C    S1C    S0U    S1U      EC       EU        OC         OU       MC     MU    CCSC   CCSU   YGC     YGCT    FGC    FGCT     GCT   68096.0 68096.0 7588.1  0.0   545344.0 394801.0 5609920.0  4050654.1  87952.0 83637.7 11392.0 10437.9   4592  327.582   9      8.855  336.43768096.0 68096.0  0.0    0.0   545344.0   0.0    5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 46918.8  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 46922.8  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 46937.1  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 46937.1  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 46937.1  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 64190.0  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 64190.0  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 64190.0  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 64190.0  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 64190.0  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 82152.3  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 82152.3  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 82152.3  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 82156.4  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 82156.4  5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 101737.5 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 101737.5 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 103581.5 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 103581.5 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 103581.5 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 124812.4 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 124812.4 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.57868096.0 68096.0  0.0    0.0   545344.0 124814.5 5609920.0  4043257.0  87952.0 83637.7 11392.0 10437.9   4592  327.582   9     12.997  340.578

手动强制Full gc 以后发现，内存并没有被释放，说明当前系统可能存在内存泄漏，导致对象不能被清理释放【OC：老年代空间，OU ：老年代使用空间（KB）】。 存在内存泄漏，主要是当前的对象引用没有被释放导致，比如僵尸线程的存在。说明当前系统可能存在大量的僵尸线程。进而进行进一步的排查

查看当前系统线程情况：jstack。可以看到当前线程的详细情况

[root@bigdata-service-1:/root]# jstack 5511 |  head -502018-07-20 11:59:27Full thread dump Java HotSpot(TM) 64-Bit Server VM (25.151-b12 mixed mode):"Keep-Alive-Timer" #19437 daemon prio=8 os_prio=0 tid=0x00007f8d749ce000 nid=0x4995 waiting on condition [0x00007f8bb7b2b000]   java.lang.Thread.State: TIMED_WAITING (sleeping)        at java.lang.Thread.sleep(Native Method)        at sun.net.www.http.KeepAliveCache.run(KeepAliveCache.java:172)        at java.lang.Thread.run(Thread.java:748)"http-nio-9025-exec-201" #19378 daemon prio=5 os_prio=0 tid=0x00007f8c8e3d3000 nid=0x7ffc waiting on condition [0x00007f8b3a724000]   java.lang.Thread.State: WAITING (parking)        at sun.misc.Unsafe.park(Native Method)        - parking to wait for  <0x0000000679f4cbd0> (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.tomcat.util.threads.TaskQueue.take(TaskQueue.java:103)        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:31)        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)        at java.lang.Thread.run(Thread.java:748)"http-nio-9025-exec-197" #19374 daemon prio=5 os_prio=0 tid=0x00007f8c8e3cc000 nid=0x7ff7 waiting on condition [0x00007f8b3a828000]   java.lang.Thread.State: WAITING (parking)        at sun.misc.Unsafe.park(Native Method)        - parking to wait for  <0x0000000679f4cbd0> (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.tomcat.util.threads.TaskQueue.take(TaskQueue.java:103)        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:31)        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)        at java.lang.Thread.run(Thread.java:748)"http-nio-9025-exec-196" #19373 daemon prio=5 os_prio=0 tid=0x00007f8c8a06d000 nid=0x7ff3 waiting on condition [0x00007f8b3a8aa000]   java.lang.Thread.State: WAITING (parking)        at sun.misc.Unsafe.park(Native Method)        - parking to wait for  <0x0000000679f4cbd0> (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.tomcat.util.threads.TaskQueue.take(TaskQueue.java:103)        at org.apache.tomcat.util.threads.TaskQueue.take(TaskQueue.java:31)        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1074)        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1134)

查看当前系统的线程总数：

jvm 开启的线程数：

[root@bigdata-service-1:/root]# jstack 5511 | wc -l254132

当前服务器对不同IP的建立连接数：

[root@bigdata-service-1:/root]# netstat -nat|grep ESTABLISHED|awk '{print$5}'|awk -F : '{print$1}'|sort|uniq -c|sort -rn  10244 10.27.70.185     26 10.27.70.77     26 10.24.237.150     10 10.81.83.121      7 10.29.148.127      4 10.80.101.244      3 10.27.4.125      2 127.0.0.1      2 10.80.112.35      2 10.27.87.167      2 10.25.0.162      1 10.80.112.23      1 106.11.248.20

加载当前的堆信息：

**jmap -dump:live,format=b,file=dump.hprof 5511 **

通过 Eclipse IDE MAT 插件进行堆分析

Eclipse 导入堆信息

1. 查看当前堆内存泄漏情况

堆的对象泄漏可以分析出，当前堆中存在大量的："io.netty.util.internal.InternalThreadLocalMap"这个是netty的内部线程

2. 查看当前堆中占用最大的对象

通过对堆的对象分析，可以发现，当前系统中大量存在连接池对象，从而定位到问题所在，连接池出现了泄漏。导致系统大量创建连接池，而没有释放。出现了内存泄漏

可以分析出，当前系统对外建立了大量的连接，而且连接没有释放，导致系统开启的线程数过多。通过分析连接最多的ip，定位到出现问题的节点

"elasticsearch[_client_][transport_client_boss][T#4]" #166 daemon prio=5 os_prio=0 tid=0x00007f8c9819e800 nid=0x20e3 runnable [0x00007f8c7403d000]        - locked <0x0000000674995e98> (a sun.nio.ch.Util$3)        - locked <0x0000000674995e80> (a java.util.Collections$UnmodifiableSet)        - locked <0x0000000674986f58> (a sun.nio.ch.EPollSelectorImpl)        at io.netty.channel.nio.NioEventLoop.select(NioEventLoop.java:753)        at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:886)

到此，相信大家对"如何排查CPU过载过高的问题"有了更深的了解，不妨来实际操作一番吧！这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！