November 20, 2012

• 呢兩日睇佢地release其間遇到既問題，學到D野

  permanent generation space, 真係未聽過=.=..我呢D一直只係著重點寫Java係完全唔識JVM既implementation...
  先係perm gen space爆左，改左之後輪到heap space爆=.=...

  深圳developer寫左段code, 用for-loop inside for-loop黎load DB既野
  UAT入面db得40,000條record所以無問題(不過都用左幾個鐘), production db入面有1,000,000, O(n^2)
  同事計左條數，如果memory唔爆既話，呢段code要行10年先行完

  How do you test an application that you can never replicate the production traffic?

  又有個case, deploy左個app去Websphere唔知點解唔work
  clear左websphere既cache之後再deploy就work

  仲有個好神奇既...原來用咩user 黎start websphere都有關係？
  聞說有人用root 黎踢著websphere, 結果讀唔到某個properties file所以死左
  要用wasadm開websphere先ok
  不過我都唔明, root唔係乜都睇到架咩？

  仲有呢個
  因為流量太多，有個application server比人chur死左
  唔知係咪load balancer唔知佢死左，仲一味派request過去, 一部死左既server當然唔識應啦
  就算load balancer識得搵另一部黎接替，新機無session儲起度一樣收皮
  點算？10秒sync一次？寫落dB度？仲有D objects係咪serializable?

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