[ruby-core:54391] [ruby-trunk - Bug #8148] [patch] reduce allocations due to __FILE__ and {class,module}_eval

Issue #8148 has been updated by headius (Charles Nutter).


I'd like to work with you to find more places we could be sharing frozen strings. A change over the summer made defined? results always be shared frozen strings, and apparently that was a source of lots and lots of extra string creation in Rails (according to wycats). There's many other such opportunities.

If course if __FILE__ were always returning shared, frozen Strings, it would be far cheaper; one String ever for a given filename.
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Bug #8148: [patch] reduce allocations due to __FILE__ and {class,module}_eval
https://bugs.ruby-lang.org/issues/8148#change-38655

Author: tmm1 (Aman Gupta)
Status: Open
Priority: Normal
Assignee: tmm1 (Aman Gupta)
Category: 
Target version: 
ruby -v: ruby 2.1.0dev (2013-03-22 trunk 39875) [x86_64-darwin12.2.1]


In my application, I noticed many long lived "(eval)" strings on the heap.

I also noticed many copies of filename strings when using module_eval(.., __FILE__, ..). Attached patch adds a new NODE_FILE to re-use the original path string.

./ruby -Ilib -rpp -rforwardable -e '           
  module Test      
    extend Forwardable
    def_delegators :@test, *("a".."z")
  end

  GC.start
  strings = ObjectSpace.each_object(String).select{ |s| s.frozen? && s =~ /forwardable/ }
  p strings.size
  pp strings.inject(Hash.new 0){ |h,s| h[s]+=1; h }
'

before:

    33
    {"/Users/test/code/ruby-trunk/lib/forwardable.rb"=>31,
     "forwardable"=>1,
     "/Users/test/code/ruby\\-trunk/lib/forwardable\\.rb"=>1}

after:

    4
    {"/Users/test/code/ruby-trunk/lib/forwardable.rb"=>2,
     "forwardable"=>1,
     "/Users/test/code/ruby\\-trunk/lib/forwardable\\.rb"=>1}

diff --git a/compile.c b/compile.c
index 9360f5b..54733d9 100644
--- a/compile.c
+++ b/compile.c
@@ -5149,6 +5149,12 @@ iseq_compile_each(rb_iseq_t *iseq, LINK_ANCHOR *ret, NODE * node, int poped)
 	}
 	break;
       }
+      case NODE_FILE:{
+	if (!poped) {
+	    ADD_INSN1(ret, line, putobject, iseq->location.path);
+	}
+	break;
+      }
       case NODE_ERRINFO:{
 	if (!poped) {
 	    if (iseq->type == ISEQ_TYPE_RESCUE) {
diff --git a/ext/objspace/objspace.c b/ext/objspace/objspace.c
index 720c918..2f32208 100644
--- a/ext/objspace/objspace.c
+++ b/ext/objspace/objspace.c
@@ -530,6 +530,7 @@ count_nodes(int argc, VALUE *argv, VALUE os)
 		COUNT_NODE(NODE_NIL);
 		COUNT_NODE(NODE_TRUE);
 		COUNT_NODE(NODE_FALSE);
+		COUNT_NODE(NODE_FILE);
 		COUNT_NODE(NODE_ERRINFO);
 		COUNT_NODE(NODE_DEFINED);
 		COUNT_NODE(NODE_POSTEXE);
diff --git a/node.h b/node.h
index 0fa7254..3f4345e 100644
--- a/node.h
+++ b/node.h
@@ -232,6 +232,8 @@ enum node_type {
 #define NODE_PRELUDE     NODE_PRELUDE
     NODE_LAMBDA,
 #define NODE_LAMBDA      NODE_LAMBDA
+    NODE_FILE,
+#define NODE_FILE        NODE_FILE
     NODE_LAST
 #define NODE_LAST        NODE_LAST
 };
@@ -450,6 +452,7 @@ typedef struct RNode {
 #define NEW_NIL() NEW_NODE(NODE_NIL,0,0,0)
 #define NEW_TRUE() NEW_NODE(NODE_TRUE,0,0,0)
 #define NEW_FALSE() NEW_NODE(NODE_FALSE,0,0,0)
+#define NEW_FILE() NEW_NODE(NODE_FILE,0,0,0)
 #define NEW_ERRINFO() NEW_NODE(NODE_ERRINFO,0,0,0)
 #define NEW_DEFINED(e) NEW_NODE(NODE_DEFINED,e,0,0)
 #define NEW_PREEXE(b) NEW_SCOPE(b)
diff --git a/parse.y b/parse.y
index 0f0fbe8..a177ca0 100644
--- a/parse.y
+++ b/parse.y
@@ -8429,8 +8429,7 @@ gettable_gen(struct parser_params *parser, ID id)
       case keyword_false:
 	return NEW_FALSE();
       case keyword__FILE__:
-	return NEW_STR(rb_external_str_new_with_enc(ruby_sourcefile, strlen(ruby_sourcefile),
-						    rb_filesystem_encoding()));
+	return NEW_FILE();
       case keyword__LINE__:
 	return NEW_LIT(INT2FIX(tokline));
       case keyword__ENCODING__:
diff --git a/test/ruby/test_literal.rb b/test/ruby/test_literal.rb
index e4c35e0..1dbcf8e 100644
--- a/test/ruby/test_literal.rb
+++ b/test/ruby/test_literal.rb
@@ -362,6 +362,7 @@ class TestRubyLiteral < Test::Unit::TestCase
   def test__FILE__
     assert_instance_of String, __FILE__
     assert_equal __FILE__, __FILE__
+    assert_equal __FILE__.object_id, __FILE__.object_id
     assert_equal 'test_literal.rb', File.basename(__FILE__)
   end
 
diff --git a/test/rubygems/test_gem.rb b/test/rubygems/test_gem.rb
index b6c7465..1b2ee37 100644
--- a/test/rubygems/test_gem.rb
+++ b/test/rubygems/test_gem.rb
@@ -1489,7 +1489,7 @@ class TestGem < Gem::TestCase
     assert_equal [a,b,c], Gem.detect_gemdeps
   end
 
-  LIB_PATH = File.expand_path "../../../lib".untaint, __FILE__.untaint
+  LIB_PATH = File.expand_path "../../../lib".untaint, __FILE__.dup.untaint
 
   def test_looks_for_gemdeps_files_automatically_on_start
     util_clear_gems
diff --git a/vm_eval.c b/vm_eval.c
index 7c18f70..bc54646 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -19,6 +19,8 @@ static VALUE vm_exec(rb_thread_t *th);
 static void vm_set_eval_stack(rb_thread_t * th, VALUE iseqval, const NODE *cref, rb_block_t *base_block);
 static int vm_collect_local_variables_in_heap(rb_thread_t *th, VALUE *dfp, VALUE ary);
 
+static VALUE eval_file;
+
 /* vm_backtrace.c */
 VALUE rb_vm_backtrace_str_ary(rb_thread_t *th, int lev, int n);
 
@@ -1156,7 +1158,7 @@ rb_each(VALUE obj)
 }
 
 static VALUE
-eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char *volatile file, volatile int line)
+eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, volatile VALUE file, volatile int line)
 {
     int state;
     VALUE result = Qundef;
@@ -1168,8 +1170,8 @@ eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char
     volatile int parse_in_eval;
     volatile int mild_compile_error;
 
-    if (file == 0) {
-	file = rb_sourcefile();
+    if (!RTEST(file)) {
+	file = rb_sourcefilename();
 	line = rb_sourceline();
     }
 
@@ -1184,8 +1186,8 @@ eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char
 	    if (rb_obj_is_kind_of(scope, rb_cBinding)) {
 		GetBindingPtr(scope, bind);
 		envval = bind->env;
-		if (strcmp(file, "(eval)") == 0 && bind->path != Qnil) {
-		    file = RSTRING_PTR(bind->path);
+		if (rb_str_cmp(file, eval_file) == 0 && bind->path != Qnil) {
+		    file = bind->path;
 		    line = bind->first_lineno;
 		}
 	    }
@@ -1214,7 +1216,7 @@ eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char
 	/* make eval iseq */
 	th->parse_in_eval++;
 	th->mild_compile_error++;
-	iseqval = rb_iseq_compile_on_base(src, rb_str_new2(file), INT2FIX(line), base_block);
+	iseqval = rb_iseq_compile_on_base(src, file, INT2FIX(line), base_block);
 	th->mild_compile_error--;
 	th->parse_in_eval--;
 
@@ -1242,7 +1244,7 @@ eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char
     if (state) {
 	if (state == TAG_RAISE) {
 	    VALUE errinfo = th->errinfo;
-	    if (strcmp(file, "(eval)") == 0) {
+	    if (rb_str_cmp(file, eval_file) == 0) {
 		VALUE mesg, errat, bt2;
 		ID id_mesg;
 
@@ -1272,7 +1274,7 @@ eval_string_with_cref(VALUE self, VALUE src, VALUE scope, NODE *cref, const char
 }
 
 static VALUE
-eval_string(VALUE self, VALUE src, VALUE scope, const char *file, int line)
+eval_string(VALUE self, VALUE src, VALUE scope, VALUE file, int line)
 {
     return eval_string_with_cref(self, src, scope, 0, file, line);
 }
@@ -1299,7 +1301,7 @@ VALUE
 rb_f_eval(int argc, VALUE *argv, VALUE self)
 {
     VALUE src, scope, vfile, vline;
-    const char *file = "(eval)";
+    VALUE file = eval_file;
     int line = 1;
 
     rb_scan_args(argc, argv, "13", &src, &scope, &vfile, &vline);
@@ -1321,7 +1323,7 @@ rb_f_eval(int argc, VALUE *argv, VALUE self)
     }
 
     if (!NIL_P(vfile))
-	file = RSTRING_PTR(vfile);
+	file = vfile;
     return eval_string(self, src, scope, file, line);
 }
 
@@ -1329,7 +1331,7 @@ rb_f_eval(int argc, VALUE *argv, VALUE self)
 VALUE
 ruby_eval_string_from_file(const char *str, const char *filename)
 {
-    return eval_string(rb_vm_top_self(), rb_str_new2(str), Qnil, filename, 1);
+    return eval_string(rb_vm_top_self(), rb_str_new2(str), Qnil, rb_str_new2(filename), 1);
 }
 
 struct eval_string_from_file_arg {
@@ -1341,7 +1343,7 @@ static VALUE
 eval_string_from_file_helper(void *data)
 {
     const struct eval_string_from_file_arg *const arg = (struct eval_string_from_file_arg*)data;
-    return eval_string(rb_vm_top_self(), rb_str_new2(arg->str), Qnil, arg->filename, 1);
+    return eval_string(rb_vm_top_self(), rb_str_new2(arg->str), Qnil, rb_str_new2(arg->filename), 1);
 }
 
 VALUE
@@ -1368,7 +1370,7 @@ ruby_eval_string_from_file_protect(const char *str, const char *filename, int *s
 VALUE
 rb_eval_string(const char *str)
 {
-    return ruby_eval_string_from_file(str, "eval");
+    return eval_string(rb_vm_top_self(), rb_str_new2(str), Qnil, eval_file, 1);
 }
 
 /**
@@ -1509,7 +1511,7 @@ rb_yield_refine_block(VALUE refinement, VALUE refinements)
 
 /* string eval under the class/module context */
 static VALUE
-eval_under(VALUE under, VALUE self, VALUE src, const char *file, int line)
+eval_under(VALUE under, VALUE self, VALUE src, VALUE file, int line)
 {
     NODE *cref = vm_cref_push(GET_THREAD(), under, NOEX_PUBLIC, NULL);
 
@@ -1534,7 +1536,7 @@ specific_eval(int argc, VALUE *argv, VALUE klass, VALUE self)
 	return yield_under(klass, self, Qundef);
     }
     else {
-	const char *file = "(eval)";
+	VALUE file = eval_file;
 	int line = 1;
 
 	rb_check_arity(argc, 1, 3);
@@ -1547,7 +1549,7 @@ specific_eval(int argc, VALUE *argv, VALUE klass, VALUE self)
 	if (argc > 2)
 	    line = NUM2INT(argv[2]);
 	if (argc > 1) {
-	    file = StringValuePtr(argv[1]);
+	    file = StringValue(argv[1]);
 	}
 	return eval_under(klass, self, argv[0], file, line);
     }
@@ -1928,6 +1930,9 @@ rb_current_realfilepath(void)
 void
 Init_vm_eval(void)
 {
+    eval_file = rb_str_new2("(eval)");
+    rb_gc_register_address(&eval_file);
+
     rb_define_global_function("eval", rb_f_eval, -1);
     rb_define_global_function("local_variables", rb_f_local_variables, 0);
     rb_define_global_function("iterator?", rb_f_block_given_p, 0);



-- 
http://bugs.ruby-lang.org/