java服务负载高解决流程

排查流程

1. 定位进程找出哪个进程的问题
2. 找出进程对应线程id
3. 线程id--->16进制 : 问题线程的id 转换为16进制线程id
4. 找出线程的详细信息: jstack +进程id | grep -i +线程的16进制id，与开发沟通
5. jmap -heap +进程id 显示jvm的内存使用情况
6. jmap (导出 jvm内存的内容 )
7. 给开发分析jvm导出文件

排查案例

# 1.找出问题java进程
top  # 查找出占用高的进程 ,为24574

# 2.通过进程,找出问题线程
top -Hp 24574      
# 查找出占用高的线程，为24671
# -H 代表显示线程
# -p 后面跟着的是进程ID

# 3.线程id转换为16进制
echo 'obase=16;24671' |bc
605F

# 4.通过jstack pid 过滤 java线程id(16进制)信息
jstack 24574 |grep -i '605F'
"http-nio-8080-exec-9" #27 daemon prio=5 os_prio=0 tid=0x00007fb87c87b800 nid=0x605f waiting on condition [0x00007fb86054e000]

jstack 24574 |grep -A5 -i '605F'
"http-nio-8080-exec-9" #27 daemon prio=5 os_prio=0 tid=0x00007fb87c87b800 nid=0x605f waiting on condition [0x00007fb86054e000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000000867ca748> (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)


# 5.把jvm内存使用情况 导出
jmap -heap 24574    #进程id
Attaching to process ID 24574, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.401-b10

using thread-local object allocation.
Parallel GC with 4 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 0
   MaxHeapFreeRatio         = 100
   MaxHeapSize              = 2051014656 (1956.0MB)
   NewSize                  = 42991616 (41.0MB)
   MaxNewSize               = 683671552 (652.0MB)
   OldSize                  = 87031808 (83.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 0 (0.0MB)
.........


# 6.把jvm内存信息导出文件
jmap -dump:format=b,file=/tmp/java-dmp.bin 24574
# format=b: 指定了转储文件的格式为二进制（binary）
# file=/tmp/java-dmp.bin: 指定了输出文件的路径和名称
# 24574: 这是你要生成堆转储的 Java 进程的进程 ID（PID）

file /tmp/java-dmp.bin
/tmp/java-dmp.bin: data
ll /tmp/java-dmp.bin
-rw-------. 1 root root 90954966 6月  13 12:36 /tmp/java-dmp.bin


# 7.给到开发进行分析