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java服务器load飚高排查思路.md

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Load 是指对计算机干活多少的度量（WikiPedia：the system load is a measure of the amount of work that a computer system is doing），简单的说是进程队列的长度。Load Average 就是一段时间 (1 分钟、5分钟、15分钟) 内平均 Load

通过uptime命令可以查看当前的load，如果值很高。一般情况是java某些线程长期占用资源、死锁、死循环等导致某个进程占用的CPU资源过高。大致可以从以下几个角度来排查：

1.首先通过jps命令，查看当前进程id，如id为 28174

2.查看该进程下的线程资源使用情况

top -p 28174 –H  

32694 root      20   0 3249m 2.0g  11m S    2  6.4   3:31.12 java                      
28175 root      20   0 3249m 2.0g  11m S    0  6.4   0:00.06 java                   
28176 root      20   0 3249m 2.0g  11m S    0  6.4   1:40.79 java                   
28177 root      20   0 3249m 2.0g  11m S    0  6.4   1:41.12 java                   
28178 root      20   0 3249m 2.0g  11m S    0  6.4   1:41.11 java                   
28179 root      20   0 3249m 2.0g  11m S    0  6.4   1:41.33 java                   
28180 root      20   0 3249m 2.0g  11m S    0  6.4   1:41.58 java                   
28181 root      20   0 3249m 2.0g  11m S    0  6.4   1:40.36 java                   
28182 root      20   0 3249m 2.0g  11m S    0  6.4   1:41.02 java                   
28183 root      20   0 3249m 2.0g  11m S    0  6.4   1:40.96 java                   
28184 root      20   0 3249m 2.0g  11m S    0  6.4   4:38.30 java                   
28185 root      20   0 3249m 2.0g  11m S    0  6.4   0:00.46 java                   
28186 root      20   0 3249m 2.0g  11m S    0  6.4   0:01.83 java                   
28187 root      20   0 3249m 2.0g  11m S    0  6.4   0:00.00 java                   
28189 root      20   0 3249m 2.0g  11m S    0  6.4   0:00.01 java                   
28190 root      20   0 3249m 2.0g  11m S    0  6.4   0:49.01 java

3.打印JAVA进程28174的堆栈信息

jstack 28174 >> stack.log

4.将cpu消耗高的线程的pid换算为16进制

printf 0x%x 32694

转换后的16进制为 0x7fb6

5.从刚才的栈日志中查找该线程正在运行的方法

grep 0x7fb6  stack.log -a3

"MSXMLProcessorThread" prio=10 tid=0x00002b469923a800 [color=darkred]nid=0x7fb6[/color] sleeping[0x00002b46b0200000]    
   java.lang.Thread.State: TIMED_WAITING (sleeping)    
        at java.lang.Thread.sleep(Native Method)    
        at com.adventnet.management.xml.MSXmlProcessor.listen(MSXmlProcessor.java:279)    
        at com.adventnet.management.xml.MSXmlProcessor.run(MSXmlProcessor.java:264)    
        at java.lang.Thread.run(Thread.java:619)

6.另外也可以查找正在运行的线程，及线程处于运行状态的位置，从这些线程中来查找资源消耗过高的代码。

grep RUNNABLE stack.log  -a1

image

less a.log |awk '{FS="java.lang.Thread.State:";print $2}'|sort |uniq -c |sort -nr

image

7、查看当前jvm内存各堆区的占比

jmap -heap 8002

Heap Configuration:
   MinHeapFreeRatio         = 40
   MaxHeapFreeRatio         = 70
   MaxHeapSize              = 2147483648 (2048.0MB)
   NewSize                  = 786432000 (750.0MB)
   MaxNewSize               = 786432000 (750.0MB)
   OldSize                  = 1361051648 (1298.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 39845888 (38.0MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 398458880 (380.0MB)
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
New Generation (Eden + 1 Survivor Space):
   capacity = 707788800 (675.0MB)
   used     = 383204272 (365.4520721435547MB)
   free     = 324584528 (309.5479278564453MB)
   54.14104772497107% used
Eden Space:
   capacity = 629145600 (600.0MB)
   used     = 334989624 (319.4710006713867MB)
   free     = 294155976 (280.5289993286133MB)
   53.24516677856445% used
From Space:
   capacity = 78643200 (75.0MB)
   used     = 48214648 (45.98107147216797MB)
   free     = 30428552 (29.01892852783203MB)
   61.30809529622396% used
To Space:
   capacity = 78643200 (75.0MB)
   used     = 0 (0.0MB)
   free     = 78643200 (75.0MB)
   0.0% used
concurrent mark-sweep generation:
   capacity = 1361051648 (1298.0MB)
   used     = 985748664 (940.0831832885742MB)
   free     = 375302984 (357.9168167114258MB)
   72.4255148912615% used

49647 interned Strings occupying 5512480 bytes.