Feature #5291: Enabling GC Profiler GC_PROFILE_MORE_DETAIL and CALC_EXACT_MALLOC_SIZE

[Charlie Savage]

I would like to hook ruby-prof into the new GC profiler. However, by default a lot of the profile stats are disabled by these two defines in gcc.c.

#define GC_PROFILE_MORE_DETAIL 0
#define CALC_EXACT_MALLOC_SIZE 0

To turn on these stats, you have to modify the ruby source code! That is a high barrier for most people.

So would it be possible to:

• Set them to 1 by default. Or would this be too much of a performance hit?

• or -

• Remove the lines entirely and then change the logic in the file from this:

#if GC_PROFILE_MORE_DETAIL

To this:

#if defined?(GC_PROFILE_MORE_DETAIL)

Then when buildig Ruby you could tell the compiler to define the symbols (-DGC_PROFILE_MORE_DETAIL).

• or -

• Add these two defines to the ./configure script so they end up in config.h. That would make it easy for users to enable them if they wish, and would be also allow ruby-prof to use them too.

Would a patch be accepted to do this?

[Eric Wong]

Charlie Savage [e-mail] wrote:

#define CALC_EXACT_MALLOC_SIZE 0

I tried flipping this a few months back in trunk but didn't have time to
investigate what went wrong when I did. I'm not sure how much people
care for it or if it's even maintained/tested by anyone (I'm not sure
I care).

I have found (and helped fix at least one) 3rd-party extensions that had
an issue with this (due to a x*alloc() paired with a regular free() or
vice-versa). So I suspect this is a common (but currently non-fatal)
bug in other extensions, too.

Anyways, several (most?) malloc implementations support
malloc_usable_size() (or similar) and have various hooks that could be
used to instrument malloc. Unfortunately the various extensions I know
of aren't compatible with each other (dlmalloc/ptmalloc, tcmalloc,
jemalloc).

[Charlie Savage]

FYI, pairing a xalloc with a free can be fatal on windows depending on how Ruby is built (mingw is safe, VC++ isn't) and what runtime c libaries are used. See the "Caution" note at the bottom of:

http://msdn.microsoft.com/en-us/library/2kzt1wy3%28v=vs.71%29.aspx

Thanks for fixing them!

[Koichi Sasada]

(2011/09/06 23:04), Charlie Savage wrote:

FYI, pairing a xalloc with a free can be fatal on windows depending on how Ruby is built (mingw is safe, VC++ isn't) and what runtime c libaries are used. See the "Caution" note at the bottom of:

Good point. This measurements can check such errors :P

--
// SASADA Koichi at atdot dot net

[Koichi Sasada]

(2011/09/06 22:05), Charlie Savage wrote:

Issue #5291 has been reported by Charlie Savage.

---

Feature #5291: Enabling GC Profiler GC_PROFILE_MORE_DETAIL and CALC_EXACT_MALLOC_SIZE
http://redmine.ruby-lang.org/issues/5291

Author: Charlie Savage
Status: Open
Priority: Normal
Assignee:
Category: core
Target version: 1.9.3

I would like to hook ruby-prof into the new GC profiler. However, by default a lot of the profile stats are disabled by these two defines in gcc.c.

#define GC_PROFILE_MORE_DETAIL 0
#define CALC_EXACT_MALLOC_SIZE 0

To turn on these stats, you have to modify the ruby source code! That is a high barrier for most people.

So would it be possible to:

• Set them to 1 by default. Or would this be too much of a performance hit?

• or -

• Remove the lines entirely and then change the logic in the file from this:

#if GC_PROFILE_MORE_DETAIL

To this:

#if defined?(GC_PROFILE_MORE_DETAIL)

Then when buildig Ruby you could tell the compiler to define the symbols (-DGC_PROFILE_MORE_DETAIL).

• or -

• Add these two defines to the ./configure script so they end up in config.h. That would make it easy for users to enable them if they wish, and would be also allow ruby-prof to use them too.

Would a patch be accepted to do this?

How about it?

Index: gc.c
===================================================================
--- gc.c (revision 33165)
+++ gc.c (working copy)
@@ -93,7 +93,10 @@
int ruby_gc_debug_indent = 0;

/* for GC profile */
+#ifndef GC_PROFILE_MORE_DETAIL
#define GC_PROFILE_MORE_DETAIL 0
+#endif
+
typedef struct gc_profile_record {
double gc_time;
double gc_mark_time;
@@ -309,7 +312,9 @@
struct gc_list *next;
};

+#ifndef CALC_EXACT_MALLOC_SIZE
#define CALC_EXACT_MALLOC_SIZE 0
+#endif

typedef struct rb_objspace {
struct {

--
// SASADA Koichi at atdot dot net

[Charlie Savage]

Yes, that would be much better. Is it too late for this to be part of 1.9.3?

Thank you!

Charlie

[Koichi Sasada]

• Status changed from Open to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r33243.
Charlie, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• gc.c (GC_PROFILE_MORE_DETAIL, CALC_EXACT_MALLOC_SIZE): define macros only if they are not defined. fixes: [Ruby 1.9 - Feature #5291]