Simplify string concatenation in log

[liketic]

We can simplify string concatenation in log without StringBuilder cause a single naive string concatenation cost is also cheap.

[codecov-io]

Codecov Report

Merging #1378 into master will decrease coverage by 0.2%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1378      +/-   ##
==========================================
- Coverage   32.57%   32.37%   -0.21%     
==========================================
  Files         691      691              
  Lines       34537    34534       -3     
  Branches     6812     6812              
==========================================
- Hits        11252    11180      -72     
- Misses      21357    21419      +62     
- Partials     1928     1935       +7

Impacted Files	Coverage Δ
...libaba/dubbo/remoting/transport/DecodeHandler.java	0% <0%> (ø)	⬆️
...bo/rpc/cluster/support/FailbackClusterInvoker.java	71.79% <0%> (-12.83%)	⬇️
...ba/dubbo/remoting/transport/netty/NettyClient.java	72.58% <0%> (-11.3%)	⬇️
...mon/serialize/support/dubbo/GenericDataOutput.java	66.31% <0%> (-9.13%)	⬇️
...a/dubbo/remoting/transport/netty/NettyChannel.java	57.5% <0%> (-8.75%)	⬇️
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-8.34%)	⬇️
...om/alibaba/dubbo/rpc/filter/ActiveLimitFilter.java	83.33% <0%> (-5.56%)	⬇️
...mmon/serialize/support/dubbo/GenericDataInput.java	58.68% <0%> (-5.02%)	⬇️
...ba/dubbo/remoting/transport/netty/NettyServer.java	67.85% <0%> (-3.58%)	⬇️
.../com/alibaba/dubbo/monitor/dubbo/DubboMonitor.java	73.14% <0%> (-2.78%)	⬇️
... and 2 more

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[kimmking]

the capacity of StringBuilder in modified statement is 16, not equals with 32 in the original one

[liketic]

Thanks @kimmking , what do you think about this change?

[kimmking]

remain original codes

[chickenlj]

I think this is a good optimization, let's wait for other suggestions before merge.

[liketic]

Thanks @chickenlj . For those cases, the naive summation will be much faster than StringBuilder. I made a simple test:

public static void main(String[] args) {

        for (int t = 0; t < 10; t++) {
            long st = System.currentTimeMillis();

            for (int i = 0; i < 100000; i++) {
                String s = "Decode decodeable message " + "xxx";
            }

            long e = System.currentTimeMillis();
            System.out.print(e - st);
            System.out.print(" ");
            
            st = System.currentTimeMillis();

            for (int i = 0; i < 100000; i++) {
                new StringBuilder(32).append("Decode decodeable message ").append("xxx").toString();
            }
            e = System.currentTimeMillis();
            System.out.println(e - st);
        }
    }

and I got output:

1 13
0 11
0 4
0 3
0 4
0 4
0 4
0 1
0 1
0 1

[beiwei30]

this is not an equivalent comparison. the compiler may optimize "Decode decodeable message " + "xxx" into "Decode decodeable message xxx" directly.

[liketic]

Thanks @beiwei30 ! That's my mistake. The test is uncorrect. The two strings cannot both be constants. 👍