Investigate high CPU usage upon 2pc

[rosik]

Recently we've noticed a problem on a customers side. Applying clusterwide configuration is a rather CPU-consuming operation.

[rosik]

Further investigations show, that it was specific to the TDG, but it can occur in other projects too. In this case, the root cause was in lots of loadstring calls.

$ cat /tmp/jitp.out
12%  /usr/share/tarantool/tdg/common/pipeline/config.lua:34
 6%  /usr/share/tarantool/tdg/common/model.lua:1450
 4%  /usr/share/tarantool/tdg/.rocks/share/tarantool/avro_schema/utils.lua:42
 4%  /usr/share/tarantool/tdg/common/model_flatten.lua:40
 4%  builtin/table.lua:13
 4%  /usr/share/tarantool/tdg/.rocks/share/tarantool/avro_schema/frontend.lua:61

====== /usr/share/tarantool/tdg/common/pipeline/config.lua ======
@@ 31 @@
      |         config_checks:assert(type(code) == 'string',
      |             'functions[%s] must be a string', fn_name)
      |         local fn, err = load(code, fn_name, 't')
   9% |         config_checks:assert(fn ~= nil,
      |             'functions[%s] syntax error: %s', fn_name, err)
      |     end
      | 

P.S. jit.p missed a line, it should point to load(code)