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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ps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
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 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
1 jstack 28174 >> stack.log
4.将cpu消耗高的线程的pid换算为16进制
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
1 grep 0x7fb6 stack.log -a3
1 2 3 4 5 6 7 "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。
1 grep RUNNABLE stack.log -a1
1 less a.log |awk '{FS="java.lang.Thread.State:";print $2}'|sort |uniq -c |sort -nr
7、查看当前jvm内存各堆区的占比
jmap -heap 8002
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 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.
