记一次java服务内存压制

机器概况

服务器centos8, 8g内存, 运行着4个java服务(不算zk),zookeeper,2个node服务
其中,2个java服务是主要服务,运行着网站基本数据交互和搜索接口.

效果

image.png

标记出来的4个点依次是:
配置优化前的峰值
配置优化当时
配置优化后的峰值
配置优化后的谷值(大致对应最大应用jvm内存回收后)

步骤

1. sudo jps 查看对应应用的pid

2. sudo jmap -heap <pid> 查看对应进程的堆内存使用情况

[www@prod:~]$ sudo jmap -heap 589

Attaching to process ID 589, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 25.172-b11

using thread-local object allocation.
Parallel GC with 2 thread(s)

Heap Configuration:
   MinHeapFreeRatio         = 0
   MaxHeapFreeRatio         = 100
   MaxHeapSize              = 2011168768 (1918.0MB)
   NewSize                  = 41943040 (40.0MB)
   MaxNewSize               = 670040064 (639.0MB)
   OldSize                  = 83886080 (80.0MB)
   NewRatio                 = 2
   SurvivorRatio            = 8
   MetaspaceSize            = 21807104 (20.796875MB)
   CompressedClassSpaceSize = 1073741824 (1024.0MB)
   MaxMetaspaceSize         = 17592186044415 MB
   G1HeapRegionSize         = 0 (0.0MB)

Heap Usage:
PS Young Generation
Eden Space:
   capacity = 445120512 (424.5MB)
   used     = 220195560 (209.9948501586914MB)
   free     = 224924952 (214.5051498413086MB)
   49.46875150970351% used
From Space:
   capacity = 11010048 (10.5MB)
   used     = 10060200 (9.594154357910156MB)
   free     = 949848 (0.9058456420898438MB)
   91.37289864676339% used
To Space:
   capacity = 12058624 (11.5MB)
   used     = 0 (0.0MB)
   free     = 12058624 (11.5MB)
   0.0% used
PS Old Generation
   capacity = 93847552 (89.5MB)
   used     = 22882704 (21.822647094726562MB)
   free     = 70964848 (67.67735290527344MB)
   24.3828459158956% used

20553 interned Strings occupying 2519416 bytes.

上面的java进程里, 配置的最大堆内存为 1918.0MB, 而实际运行中, 新生代和老年代加起来不过514M(424.5+89.5),其中老年代不过使用了 24%. 所以最大 512M的堆内存就足够了.

3. 服务启动命令添加 Xms Xmx 参数
   nohup java -Xms512m -Xmx512m -jar xxx.jar 其他参数 >logs/run.log 2>&1 &