test scalability for json lib

[AsterDY]

Case

• Repeatedly marshal the same object and unmarshal outcome json into a new object, for N times
• Create T number of threads (or processes) to execute above task.
• Adjust T and N meanwhile, ensuring total works always equal to T*N

  Environment

  goos: darwin
  goarch: amd64
  cpu: Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz

  Result

  It's very clear that for JSON lib, its processability doesn't grow linearly with the number of CPUs. And there is a abvious threshold once paralleled threads (or processes) number goes above half of the CPU cores

  === RUN   TestScalability_Process
  === RUN   TestScalability_Process/sonic
  single-process
  1 processes total cost: 169785us
  1/4-processes
  4 processes total cost: 73421us
  half-processes
  8 processes total cost: 72286us
  3/4-processes
  12 processes total cost: 85187us
  full-processes
  16 processes total cost: 100788us
  full-processes-1
  15 processes total cost: 99805us
  === RUN   TestScalability_Process/std
  single-process
  1 processes total cost: 315315us
  1/4-processes
  4 processes total cost: 105815us
  half-processes
  8 processes total cost: 90710us
  3/4-processes
  12 processes total cost: 107567us
  full-processes
  16 processes total cost: 115681us
  full-processes-1
  15 processes total cost: 117348us
  --- PASS: TestScalability_Process (1.45s)
  --- PASS: TestScalability_Process/sonic (0.60s)
  --- PASS: TestScalability_Process/std (0.85s)
  === RUN   TestScalability_Thread
  num cpu: 16
  === RUN   TestScalability_Thread/sonic
  single-thread
  1 threads total cost: 150786us
  1/4-threads
  4 threads total cost: 51560us
  half-threads
  8 threads total cost: 37515us
  3/4-threads
  12 threads total cost: 36387us
  full-threads
  16 threads total cost: 39338us
  full-threads-1
  15 threads total cost: 40201us
  === RUN   TestScalability_Thread/std
  single-thread
  1 threads total cost: 287707us
  1/4-threads
  4 threads total cost: 96182us
  half-threads
  8 threads total cost: 88373us
  3/4-threads
  12 threads total cost: 96573us
  full-threads
  16 threads total cost: 115144us
  full-threads-1
  15 threads total cost: 110567us