[GitHub] [apisix] tokers commented on issue #2930: optimization: string concatenation in sls-logger.lua

[GitBox <gi...@apache.org>]

tokers commented on issue #2930:
URL: https://github.com/apache/apisix/issues/2930#issuecomment-737628759


   > Please give some performance testing to prove use string concatenation is not inefficient, I have do the performance test for sls log ,can not find any inefficient issue.
   
   This is a classical bad practice for string concatenation. Just see the following snippet to benchmark it.
   
   ```lua
   local function concat_100000x_way1(s)
       local t = ""
       for i = 1, 50000 do
           t = t .. s
       end
   
       return t
   end
   
   
   local function concat_100000x_way2(s)
       local t = {}
       for i = 1, 50000 do
           t[i] = s
       end
   
       return table.concat(t)
   end
   
   
   local function bench(func, s)
       local s = os.time()
       func(s)
       print("cost time: ", os.time() - s)
   end
   
   
   bench(concat_100000x_way1, string.rep("haha", 50))
   bench(concat_100000x_way2, string.rep("haha", 50))
   ```


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