7月 242020
 

按官方提示https://github.com/naver/pinpoint-docker ,通过docker安装pinpoint时,遇到端口冲突问题

 docker-compose up -d                                                                                                                                                                                             
Creating network "pinpoint-docker_pinpoint" with driver "bridge"                                                                                                                                                   
Creating pinpoint-docker_zoo3_1    ... done                                                                                                                                                                        
Creating pinpoint-docker_zoo2_1    ... done                                                                                                                                                                        
Creating pinpoint-flink-jobmanager ... done                                                                                                                                                                        
Creating pinpoint-docker_zoo1_1     ... done                                                                                                                                                                       
Creating pinpoint-mysql             ... done                                                                                                                                                                       
Creating pinpoint-hbase             ... error                                                                                                                                                                      
Creating pinpoint-flink-taskmanager ... done                                                                                                                                                                       
                                                                                                                                                                                                                   
ERROR: for pinpoint-hbase  Cannot start service pinpoint-hbase: Ports are not available: listen tcp 0.0.0.0:2180: bind: An attempt was made to access a socket in a way forbidden by its access permissions.       
                                                                                                                                                                                                                   
ERROR: for pinpoint-hbase  Cannot start service pinpoint-hbase: Ports are not available: listen tcp 0.0.0.0:2180: bind: An attempt was made to access a socket in a way forbidden by its access permissions.       
Encountered errors while bringing up the project.                                                                                                                                                                  

根据官方提示,修改pinpoint-docker文件夹下的.env文件,修改hbase端口即可,比如我修改为了12180 Continue reading »

10月 222019
 

讲分布式Id生成的文章很多,其中雪花算法也提到过多次,本文不再赘述,只是给出资源汇总,仅供参考。

snowflake-snowflake-2010

twitter原版,scala编写,地址:https://github.com/twitter-archive/snowflake

java版本snowflake

代码源地址 参见

  • https://github.com/beyondfengyu/SnowFlake
  • https://github.com/souyunku/SnowFlake

Leaf——美团点评分布式ID生成系统

介绍参见Leaf——美团点评分布式ID生成系统 https://tech.meituan.com/2017/04/21/mt-leaf.html
代码参见https://github.com/Meituan-Dianping/Leaf
9月 132019
 

课程链接

课程:https://url.163.com/VD8

java锁

synchronized

在jdk 1.5以后,优化了,使其性能并不是像很多帖子说的那样,“非常重”

JUC lock

方法 说明
lock() 获取锁,如果锁被暂用则一直等待
tryLock() 如果获取锁的时候锁被占用就返回false,否则返回true
tryLock(long time, TimeUnit unit) 比起tryLock,多出等待时间
unLock()
lockInterruptibly()

Continue reading »

3月 222019
 

elasticsearch启动时报错:

Java HotSpot™ 64-Bit Server VM warning: INFO: os::commit_memory(0x00000000e5330000, 449642496, 0) failed; error=‘Cannot allocate memory’ (errno=12)

There is insufficient memory for the Java Runtime Environment to continue.
Native memory allocation (mmap) failed to map 449642496 bytes for committing reserved memory.
An error report file with more information is saved as:
/opt/elasticsearch/hs_err_pidxxx.log

原因:没有足够的内存供JRE运行
解决:修改es配置参数

vim config/jvm.options

修改JVM参数,将其改小即可:


-Xms512m  
-Xmx512m