Firefox gc-object-logging (+ winconsole) (based on http://philikon.wordpress.com/2011/03/09/javascript-perf-avoid-creating-objects-2/)

gc-object-logging.diff

diff --git a/browser/app/nsBrowserApp.cpp b/browser/app/nsBrowserApp.cpp
--- a/browser/app/nsBrowserApp.cpp
+++ b/browser/app/nsBrowserApp.cpp
@@ -69,16 +69,20 @@
 #define strcasecmp _stricmp
 #endif
 #include "BinaryPath.h"
 
 #include "nsXPCOMPrivate.h" // for MAXPATHLEN and XPCOM_DLL
 
 #include "mozilla/Telemetry.h"
 
+#if defined(XP_WIN) && !MOZ_WINCONSOLE
+#error woot
+#endif
+
 static void Output(const char *fmt, ... )
 {
   va_list ap;
   va_start(ap, fmt);
 
 #if defined(XP_WIN) && !MOZ_WINCONSOLE
   PRUnichar msg[2048];
   _vsnwprintf(msg, sizeof(msg)/sizeof(msg[0]), NS_ConvertUTF8toUTF16(fmt).get(), ap);
diff --git a/config/autoconf.mk.in b/config/autoconf.mk.in
--- a/config/autoconf.mk.in
+++ b/config/autoconf.mk.in
@@ -175,16 +175,17 @@ VPX_ARM_ASM = @VPX_ARM_ASM@
 VPX_NEED_OBJ_INT_EXTRACT = @VPX_NEED_OBJ_INT_EXTRACT@
 LIBJPEG_TURBO_AS = @LIBJPEG_TURBO_AS@
 LIBJPEG_TURBO_ASFLAGS = @LIBJPEG_TURBO_ASFLAGS@
 LIBJPEG_TURBO_X86_ASM = @LIBJPEG_TURBO_X86_ASM@
 LIBJPEG_TURBO_X64_ASM = @LIBJPEG_TURBO_X64_ASM@
 NS_PRINTING = @NS_PRINTING@
 MOZ_PDF_PRINTING = @MOZ_PDF_PRINTING@
 MOZ_CRASHREPORTER = @MOZ_CRASHREPORTER@
+MOZ_WINCONSOLE = @MOZ_WINCONSOLE@
 MOZ_HELP_VIEWER = @MOZ_HELP_VIEWER@
 MOC = @MOC@
 RCC = @RCC@
 MOZ_NSS_PATCH = @MOZ_NSS_PATCH@
 MOZ_WEBGL = @MOZ_WEBGL@
 MOZ_ANGLE = @MOZ_ANGLE@
 MOZ_DIRECTX_SDK_PATH = @MOZ_DIRECTX_SDK_PATH@
 MOZ_DIRECTX_SDK_CPU_SUFFIX = @MOZ_DIRECTX_SDK_CPU_SUFFIX@
diff --git a/configure.in b/configure.in
--- a/configure.in
+++ b/configure.in
@@ -6018,16 +6018,17 @@ fi
 
 dnl ========================================================
 dnl = Breakpad crash reporting (on by default on supported platforms)
 dnl ========================================================
 
 case $target in
 i?86-*-mingw*|x86_64-*-mingw*)
   MOZ_CRASHREPORTER=1
+  MOZ_WINCONSOLE=1
   ;;
 i?86-apple-darwin*|powerpc-apple-darwin*|x86_64-apple-darwin*)
   MOZ_CRASHREPORTER=1
   ;;
 i?86-*-linux*|x86_64-*-linux*|arm-*-linux*)
   if test "$MOZ_ENABLE_GTK2"; then
     MOZ_CRASHREPORTER=1
   fi
@@ -6056,17 +6057,19 @@ if test -n "$MOZ_CRASHREPORTER"; then
 
     MOZ_CHECK_HEADERS([curl/curl.h], [], [AC_MSG_ERROR([Couldn't find curl/curl.h which is required for the crash reporter.  Use --disable-crashreporter to disable the crash reporter.])])
   fi
 
   if (test "$OS_ARCH" != "$HOST_OS_ARCH"); then
     AC_MSG_ERROR([Breakpad tools do not support compiling on $HOST_OS_ARCH while targeting $OS_ARCH.  Use --disable-crashreporter.])
   fi
 fi
-
+if test -n "$MOZ_WINCONSOLE"; then
+   AC_DEFINE(MOZ_WINCONSOLE)
+fi
 MOZ_ARG_WITH_STRING(crashreporter-enable-percent,
 [  --with-crashreporter-enable-percent=NN
                           Enable sending crash reports by default on NN% of users. (default=100)],
 [ val=`echo $withval | sed 's/[^0-9]//g'`
     MOZ_CRASHREPORTER_ENABLE_PERCENT="$val"])
 
 if test -z "$MOZ_CRASHREPORTER_ENABLE_PERCENT"; then
    MOZ_CRASHREPORTER_ENABLE_PERCENT=100
@@ -8428,16 +8431,17 @@ AC_SUBST(MOZ_PROFILELOCKING)
 AC_SUBST(ENABLE_TESTS)
 AC_SUBST(IBMBIDI)
 AC_SUBST(MOZ_UNIVERSALCHARDET)
 AC_SUBST(ACCESSIBILITY)
 AC_SUBST(MOZ_SPELLCHECK)
 AC_SUBST(MOZ_JAVA_COMPOSITOR)
 AC_SUBST(MOZ_USER_DIR)
 AC_SUBST(MOZ_CRASHREPORTER)
+AC_SUBST(MOZ_WINCONSOLE)
 AC_SUBST(MOZ_MAINTENANCE_SERVICE)
 AC_SUBST(MOZ_UPDATER)
 AC_SUBST(MOZ_ANGLE)
 AC_SUBST(MOZ_DIRECTX_SDK_PATH)
 AC_SUBST(MOZ_DIRECTX_SDK_CPU_SUFFIX)
 AC_SUBST(MOZ_D3DX9_VERSION)
 AC_SUBST(MOZ_D3DX9_CAB)
 AC_SUBST(MOZ_D3DCOMPILER_CAB)
diff --git a/js/src/jsgcinlines.h b/js/src/jsgcinlines.h
--- a/js/src/jsgcinlines.h
+++ b/js/src/jsgcinlines.h
@@ -423,61 +423,93 @@ TryNewGCThing(JSContext *cx, js::gc::All
 }
 
 } /* namespace gc */
 } /* namespace js */
 
 inline JSObject *
 js_NewGCObject(JSContext *cx, js::gc::AllocKind kind)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCObject %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }
     JS_ASSERT(kind >= js::gc::FINALIZE_OBJECT0 && kind <= js::gc::FINALIZE_OBJECT_LAST);
     return js::gc::NewGCThing<JSObject>(cx, kind, js::gc::Arena::thingSize(kind));
 }
 
 inline JSObject *
 js_TryNewGCObject(JSContext *cx, js::gc::AllocKind kind)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("TryNewGCObject %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }
     JS_ASSERT(kind >= js::gc::FINALIZE_OBJECT0 && kind <= js::gc::FINALIZE_OBJECT_LAST);
     return js::gc::TryNewGCThing<JSObject>(cx, kind, js::gc::Arena::thingSize(kind));
 }
 
 inline JSString *
 js_NewGCString(JSContext *cx)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCString %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }	
     return js::gc::NewGCThing<JSString>(cx, js::gc::FINALIZE_STRING, sizeof(JSString));
 }
 
 inline JSShortString *
 js_NewGCShortString(JSContext *cx)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCShortString %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }
     return js::gc::NewGCThing<JSShortString>(cx, js::gc::FINALIZE_SHORT_STRING, sizeof(JSShortString));
 }
 
 inline JSExternalString *
 js_NewGCExternalString(JSContext *cx)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCExtString %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }	
     return js::gc::NewGCThing<JSExternalString>(cx, js::gc::FINALIZE_EXTERNAL_STRING,
                                                 sizeof(JSExternalString));
 }
 
 inline JSScript *
 js_NewGCScript(JSContext *cx)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCScript %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }	
     return js::gc::NewGCThing<JSScript>(cx, js::gc::FINALIZE_SCRIPT, sizeof(JSScript));
 }
 
 inline js::Shape *
 js_NewGCShape(JSContext *cx)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCShape %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }	
     return js::gc::NewGCThing<js::Shape>(cx, js::gc::FINALIZE_SHAPE, sizeof(js::Shape));
 }
 
 inline js::BaseShape *
 js_NewGCBaseShape(JSContext *cx)
 {
+    if (cx->hasfp() && cx->fp()->isScriptFrame()) {
+        printf("NewGCBaseShape %s:%d\n", cx->fp()->script()->filename,
+               js_PCToLineNumber(cx, cx->fp()->script(), js_GetCurrentBytecodePC(cx)));
+    }
     return js::gc::NewGCThing<js::BaseShape>(cx, js::gc::FINALIZE_BASE_SHAPE, sizeof(js::BaseShape));
 }
 
 #if JS_HAS_XML_SUPPORT
 extern JSXML *
 js_NewGCXML(JSContext *cx);
 #endif
 
diff --git a/modules/libpref/src/init/all.js b/modules/libpref/src/init/all.js
--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -629,22 +629,22 @@ pref("privacy.donottrackheader.enabled",
 pref("dom.event.contextmenu.enabled",       true);
 
 pref("javascript.enabled",                  true);
 pref("javascript.options.strict",           false);
 #ifdef DEBUG
 pref("javascript.options.strict.debug",     true);
 #endif
 pref("javascript.options.relimit",          true);
-pref("javascript.options.methodjit.content", true);
-pref("javascript.options.methodjit.chrome",  true);
+pref("javascript.options.methodjit.content", false);
+pref("javascript.options.methodjit.chrome",  false);
 pref("javascript.options.pccounts.content", false);
 pref("javascript.options.pccounts.chrome",  false);
 pref("javascript.options.methodjit_always", false);
-pref("javascript.options.jit_hardening", true);
+pref("javascript.options.jit_hardening", false);
 pref("javascript.options.typeinference", true);
 // This preference limits the memory usage of javascript.
 // If you want to change these values for your device,
 // please find Bug 417052 comment 17 and Bug 456721
 // Comment 32 and Bug 613551.
 pref("javascript.options.mem.high_water_mark", 128);
 pref("javascript.options.mem.max", -1);
 pref("javascript.options.mem.gc_per_compartment", true);

parselog.py

import os, sys, re
from itertools import chain
from collections import Counter, defaultdict

groups = defaultdict(Counter)
files = defaultdict(Counter)

# dta specific
r = re.compile(r"^(?:Try)?NewGC(.+?)\s(.+?/dta.+)$")

with open(sys.argv[1]) as fp:
    for l in fp:
        m = r.search(l.strip())
        if not m:
            continue
        t, f = m.groups()
        _f, _l = f.rsplit(":", 1)
        _t = "line {0}, {1}".format(_l, t)
        groups[t][f] += 1
        files[_f][_t] += 1

for k,g in chain(groups.iteritems(), files.iteritems()):
    g = sorted(([f,c] for (f,c) in g.items() if c > 1000),
               key=lambda x: x[1],
               reverse=True)
    if not g:
        continue

    print k
    for i in g:
        print "{1:>10}: {0}".format(*i)
    print

Logging is verrry slow and verrry noisy.
Also expect a lot of crap to be logged.

Repeat after me: Not all GCThings are bad, just those that can be avoided without impacting performance.
Prime examples for optimizations are tight inner loops that use forEach/for each/Iterator. Not only are plain loops (usually) faster, also less GC objects are used.