It is a module that provider simple cache system on perl. You can save data in to memory with a specified life time and idle period and take it back later.
本文示範一個簡單方法編寫多綫程網絡緩存服務。通過 SocketService.pm 函數包輕鬆開發，基本上你只需要關心一個 callback，處理一個新網絡連接的業務邏輯便可，其它的瑣碎和高深服務開發代碼可以交函數包完成。
echo 3 > /proc/sys/vm/drop_caches
In some case, you may get a out of memory error due to memory used up even by I/O cache. Such kind of error definitely is a bugs but this may cause your process failure. I came across in KVM on ubuntu 12.04.
You may do this after backup or restore since these commands usually fill up I/O cache.