[Tarantool-patches] [PATCH luajit] tools: make memprof parser output user-friendly

[Sergey Kaplun]

Igor,

Thanks for the review!

On 26.03.21, Igor Munkin wrote:
> Sergey,
> 
> Thanks for the patch! LGTM, except the couple of nits below.
> 
> On 26.03.21, Sergey Kaplun wrote:
> > Profiler parser output looks like the following:
> > | ALLOCATIONS
> > | @true_memleak.lua:6, line 9: 3	144	0
> > | @true_memleak.lua:6, line 8: 2	41	0
> > 
> > Line of function definition is confusing for users and looks redundant.
> 
> Typo: s/is confusing for/confuses/.
> 
> > Also, these "magic numbers" may shock users.
> 
> Minor: Are you still talking about the line of function definition or
> about the events/bytes here? It's a bit unclear from the wording.

Thanks, reworded the commit message as the following:
===================================================================
tools: make memprof parser output user-friendly

Profiler parser output looks like the following:
| ALLOCATIONS
| @true_memleak.lua:6, line 9: 3	144	0
| @true_memleak.lua:6, line 8: 2	41	0

Line of function definition confuses users and looks redundant.
Also, these "magic numbers" following after event location may shock
users.

This patch removes lines of function definitions from the output. Info
about the line function definition is saved inside symbol info table by
field `linedefined` (it can be used later for a user's custom parser).
Field `name` is renamed to `source`. Moreover, explanatory words and
signs are added to numbers for more verbose output.

After the patch, profiler parser output looks like the following:
| ALLOCATIONS
| @true_memleak.lua:9: 3 events	+144 bytes	-0 bytes
| @true_memleak.lua:8: 2 events	+41 bytes	-0 bytes

Resolves tarantool/tarantool#5811
Part of tarantool/tarantool#5657
===================================================================

> 
> > 
> > This patch removes lines of function definitions from the output.
> > Info about the line function definition is saved inside symbol info
> > table by field `defined` (it can be used later for a user's custom
> > parser). Moreover, explanatory words and signs are added to numbers
> > for more verbose output.
> > 
> > After the patch, profiler parser output looks like the following:
> > | ALLOCATIONS
> > | @true_memleak.lua:9: 3 events	+144 bytes	-0 bytes
> > | @true_memleak.lua:8: 2 events	+41 bytes	-0 bytes
> > 
> > Resolves tarantool/tarantool#5811
> > Part of tarantool/tarantool#5657
> > ---
> > Branch: https://github.com/tarantool/luajit/tree/skaplun/gh-5811-user-friendly-memprof
> > Tarantool branch: https://github.com/tarantool/tarantool/tree/skaplun/gh-5811-user-friendly-memprof
> > Issues:
> > * https://github.com/tarantool/tarantool/issues/5811
> > * https://github.com/tarantool/tarantool/issues/5657
> > 
> >  test/tarantool-tests/misclib-memprof-lapi.test.lua | 4 +++-
> >  tools/memprof/humanize.lua                         | 2 +-
> >  tools/utils/symtab.lua                             | 5 +++--
> >  3 files changed, 7 insertions(+), 4 deletions(-)
> > 

Missed ChangeLog entry, feel free to change it at your pleasure:

===================================================================
##feature/luajit

* Make LuaJIT memory profiler parser output more user-friendly (gh-5811).
  **Breaking change**: Info
  about the line function definition is saved inside symbol info table by
  field `linedefined` now. Field `name` was renamed to `source`.
===================================================================

> 
> <snipped>
> 
> > diff --git a/tools/memprof/humanize.lua b/tools/memprof/humanize.lua
> > index 109a39db..2d5814c6 100644
> > --- a/tools/memprof/humanize.lua
> > +++ b/tools/memprof/humanize.lua
> > @@ -20,7 +20,7 @@ function M.render(events, symbols)
> >  
> >    for i = 1, #ids do
> >      local event = events[ids[i]]
> > -    print(string.format("%s: %d\t%d\t%d",
> > +    print(string.format("%s: %d events\t+%d bytes\t-%d bytes",
> 
> Minor: Heh, "events" is still plural even if <event.num> is 1. Feel free
> to ignore (the current implementation might ease the postprocessing).

Valgring use plural too for different kind of messages.
| ==24036== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

Ignoring.

> 
> >        symtab.demangle(symbols, event.loc),
> >        event.num,
> >        event.alloc,
> > diff --git a/tools/utils/symtab.lua b/tools/utils/symtab.lua
> > index 03aadbd5..6cfa1065 100644
> > --- a/tools/utils/symtab.lua
> > +++ b/tools/utils/symtab.lua
> > @@ -25,7 +25,8 @@ local function parse_sym_lfunc(reader, symtab)
> >    local sym_line = reader:read_uleb128()
> >  
> >    symtab[sym_addr] = {
> > -    name = string_format("%s:%d", sym_chunk, sym_line),
> > +    name = sym_chunk,
> > +    defined = sym_line,
> 
> Minor: Since you split "name" into two components -- file name and line
> the function is defined -- it looks natural to me to use the same names
> as <debug.getinfo> does: source + linedefined. Anyway, feel free to
> ignore, since the naming you chose is also fine.

Yep, "backward compatibility" is broken anyway by this commit, so
I renamed these fields.
Side note: I didn't rerun tests on CI, but checked it locally.

===================================================================
diff --git a/test/tarantool-tests/misclib-memprof-lapi.test.lua b/test/tarantool-tests/misclib-memprof-lapi.test.lua
index 6aa33198..9cfa6f29 100644
--- a/test/tarantool-tests/misclib-memprof-lapi.test.lua
+++ b/test/tarantool-tests/misclib-memprof-lapi.test.lua
@@ -57,7 +57,7 @@ local function fill_ev_type(events, symbols, event_type)
     elseif symbols[addr] then
       ev_type[event.loc.line] = {
         name = string.format(
-          "%s:%d", symbols[addr].name, symbols[addr].defined
+          "%s:%d", symbols[addr].source, symbols[addr].linedefined
         ),
         num = event.num,
       }
diff --git a/tools/utils/symtab.lua b/tools/utils/symtab.lua
index 6cfa1065..3ed1dd13 100644
--- a/tools/utils/symtab.lua
+++ b/tools/utils/symtab.lua
@@ -25,8 +25,8 @@ local function parse_sym_lfunc(reader, symtab)
   local sym_line = reader:read_uleb128()
 
   symtab[sym_addr] = {
-    name = sym_chunk,
-    defined = sym_line,
+    source = sym_chunk,
+    linedefined = sym_line,
   }
 end
 
@@ -81,7 +81,7 @@ function M.demangle(symtab, loc)
   end
 
   if symtab[addr] then
-    return string_format("%s:%d", symtab[addr].name, loc.line)
+    return string_format("%s:%d", symtab[addr].source, loc.line)
   end
 
   return string_format("CFUNC %#x", addr)
===================================================================

> 
> >    }
> >  end
> >  
> 
> <snipped>
> 
> > -- 
> > 2.31.0
> > 
> 
> -- 
> Best regards,
> IM

-- 
Best regards,
Sergey Kaplun