# \[Bug:1.9\] lack consistency in hash iteration

**URL:** <https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458>\
**Category:** Development\
**Created:** [February 4, 2009, 6:52pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458 "2009-02-04T18:52:13Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 4, 2009, 6:52pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/1 "2009-02-04T18:52:13Z")

</div>

e$B1sF#$G$9!#e(B

[ruby-core:21812] e$B$GD4$Y$F$$$F5$$,IU$$$?$3$H$G$9$,!"e(B

$ ./ruby -e ‘h = {0 =\> nil}; i = 1; h.each\_key { h[i] = nil; i += 1 }’

e$B$ODd;\_$7!"e(B

$ ./ruby -e ‘h = {0 =\> nil, 1 =\> nil}; i = 2; h.each\_key { h[i] = nil; i  
+= 1 }’

e$B$OL58B%k!\<%W$K$J$j$^$9!#e(B  
e$BD\>46E\*$K$O$I$A$i$bL58B%k!\<%W$K$J$k$H;W$$$^$7$?!#e(B

e$BFC$KH?BP$,$J$1$l$P!"0J2\<$N%Q%C%A$r%3%\_%C%H$7$h$&$H;W$$$^$9!#e(B

# Index: st.c

— st.c (revision 22051)  
+++ st.c (working copy)  
@@ -653,6 +653,7 @@  
do {  
end = ptr-\>fore == table-\>head;  
retval = (\*func)(ptr-\>key, ptr-\>record, arg);

- 

```
 end = end && (ptr->fore == table->head);
 switch (retval) {
   case ST_CHECK: /* check if hash is modified during iteration 

```

# \*/ i = ptr-\>hash % table-\>num\_bins; Index: test/ruby/test\_hash.rb

— test/ruby/test\_hash.rb (revision 22051)  
+++ test/ruby/test\_hash.rb (working copy)  
@@ -849,4 +849,30 @@  
def test\_hash\_hash  
assert\_equal({0=\>2,11=\>1}.hash, {11=\>1,0=\>2}.hash)  
end  
+

- def test\_iteration\_order
- h = {1=\>nil,3=\>nil,2=\>nil,4=\>nil}
- assert\_equal([1, 3, 2, 4], h.each\_key.to\_a)
- 
- h.each\_key {|k| h[k + 10] = nil if h.size \< 8 }
- assert\_equal([1, 3, 2, 4, 11, 13, 12, 14], h.each\_key.to\_a)
- 
- h = {0=\>nil}
- i = 1
- h.each\_key do |k|
- 

```
 break if h.size == 5

```

- 

```
 h[i] = nil

```

- 

```
 i += 1

```

- end
- assert\_equal({0=\>nil,1=\>nil,2=\>nil,3=\>nil,4=\>nil}, h)
- 
- h = {0=\>nil,1=\>nil}
- i = 2
- h.each\_key do |k|
- 

```
 break if h.size == 5

```

- 

```
 h[i] = nil

```

- 

```
 i += 1

```

- end
- assert\_equal({0=\>nil,1=\>nil,2=\>nil,3=\>nil,4=\>nil}, h)
- end  
end

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 4, 2009, 7:12pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/2 "2009-02-04T19:12:44Z")

</div>

e$B$^$D$b$He(B e$B$f$-$R$m$G$9e(B

In message “Re: [ruby-dev:37910] [Bug:1.9] lack consistency in hash  
iteration”  
on Thu, 5 Feb 2009 02:51:16 +0900, Yusuke ENDOH [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
writes:

|[ruby-core:21812] e$B$GD4$Y$F$$$F5$$,IU$$$?$3$H$G$9$,!"e(B  
|  
|$ ./ruby -e ‘h = {0 =\> nil}; i = 1; h.each\_key { h[i] = nil; i += 1 }’  
|  
|e$B$ODd;\_$7!"e(B  
|  
|$ ./ruby -e ‘h = {0 =\> nil, 1 =\> nil}; i = 2; h.each\_key { h[i] = nil; i += 1 }’  
|  
|e$B$OL58B%k!\<%W$K$J$j$^$9!#e(B  
|e$BD\>46E\*$K$O$I$A$i$bL58B%k!\<%W$K$J$k$H;W$$$^$7$?!#e(B

e$B\<jH4$-$G?=$7Lu$J$$$N$G$9$,!"0J2\<$NE@$K$D$$$F65$($F$/$@$5$$!#e(B

- e$B$3$N%Q%C%A$NBP\>]$Oe(B1.9e$B$G$9$+!"e(B1.8e$B$G$9$+!)e(B
- e$B$3$N%Q%C%A$rEv$F$k$HN\>J}$H$bL58B%k!\<%W$K$J$j$^$9$+!)e(B

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 4, 2009, 7:19pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/3 "2009-02-04T19:19:47Z")

</div>

e$B1sF#$G$9!#e(B

2009/02/05 3:11 Yukihiro M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> |  
> |$ ./ruby -e ‘h = {0 =\> nil, 1 =\> nil}; i = 2; h.each\_key { h[i] = nil; i += 1 }’  
> |  
> |e$B$OL58B%k!\<%W$K$J$j$^$9!#e(B  
> |e$BD\>46E\*$K$O$I$A$i$bL58B%k!\<%W$K$J$k$H;W$$$^$7$?!#e(B
> 
> e$B\<jH4$-$G?=$7Lu$J$$$N$G$9$,!"0J2\<$NE@$K$D$$$F65$($F$/$@$5$$!#e(B

e$B$3$A$i$3$=@bL@ITB-$G?=$7Lu$"$j$^$;$s!#e(B

> - e$B$3$N%Q%C%A$NBP\>]$Oe(B1.9e$B$G$9$+!"e(B1.8e$B$G$9$+!)e(B

[Bug:1.9] e$B$N$H$\*$j!"e(B1.9 e$BMQ$G$9!#e(B

> - e$B$3$N%Q%C%A$rEv$F$k$HN\>J}$H$bL58B%k!\<%W$K$J$j$^$9$+!)e(B

e$B$O$$!"N\>J}$H$bL58B%k!\<%W$K$J$j$^$9!#e(B

e$B$"$H;d$N4D6-$Ge(B make check e$B$ODL$C$F$$$^$9!#e(B

e$B$h$m$7$/$\*4j$$$7$^$9!#e(B

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 5, 2009, 5:02pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/4 "2009-02-05T17:02:44Z")

</div>

e$B1sF#$G$9!#e(B

2009/02/05 3:25 Yukihiro M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> |  
> |e$B$O$$!“N\>J}$H$bL58B%k!\<%W$K$J$j$^$9!#e(B  
> |  
> |e$B$”$H;d$N4D6-$Ge(B make check e$B$ODL$C$F$$$^$9!#e(B
> 
> e$B$$$$$s$8$c$J$$$G$7$g$&$+!#%3%\_%C%H$7$F$/$@$5$$!#e(B

e$B$9$_$^$;$s!"$^$@%3%_%C%H$7$F$J$$$s$G$9$,!“$3$N%Q%C%A$K$O%P%0$,$”$j$^$7$?!#e(B  
e$BF1$8MWAG$rJ#?t2se(B yield e$B$9$k2DG=@-$,$"$j$^$9!#e(B

$ ./ruby -e ‘h = {1=\>1,2=\>2}; h.each {|x| p x; h.delete(2) }’  
[1, 1]  
[1, 1]

e$B$9$0$K$O2r7h:v$,;W$$$D$+$J$$$N$G!"$A$g$C$H9M$($^$9!#e(B

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 4, 2009, 7:26pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/5 "2009-02-04T19:26:14Z")

</div>

e$B$^$D$b$He(B e$B$f$-$R$m$G$9e(B

In message “Re: [ruby-dev:37912] Re: [Bug:1.9] lack consistency in hash  
iteration”  
on Thu, 5 Feb 2009 03:18:19 +0900, Yusuke ENDOH [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
writes:

|\> \* e$B$3$N%Q%C%A$NBP\>]$Oe(B1.9e$B$G$9$+!"e(B1.8e$B$G$9$+!)e(B  
|  
|[Bug:1.9] e$B$N$H$\*$j!"e(B1.9 e$BMQ$G$9!#e(B  
|  
|\> \* e$B$3$N%Q%C%A$rEv$F$k$HN\>J}$H$bL58B%k!\<%W$K$J$j$^$9$+!)e(B  
|  
|e$B$O$$!“N\>J}$H$bL58B%k!\<%W$K$J$j$^$9!#e(B  
|  
|e$B$”$H;d$N4D6-$Ge(B make check e$B$ODL$C$F$$$^$9!#e(B

e$B$$$$$s$8$c$J$$$G$7$g$&$+!#%3%\_%C%H$7$F$/$@$5$$!#e(B

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 8, 2009, 3:37pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/6 "2009-02-08T15:37:43Z")

</div>

e$B%A%1%C%He(B #1107 e$B$,99?7$5$l$^$7$?!#e(B (by Yusuke E.)

e$B%9%F!\<%?%9e(B Opene$B$+$ie(BClosede$B$KJQ99e(B  
e$B?JD=e(B % 0e$B$+$ie(B100e$B$KJQ99e(B

## Applied in changeset r22132.

[http://redmine.ruby-lang.org/issues/show/1107](http://redmine.ruby-lang.org/issues/show/1107)

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 6, 2009, 4:57pm UTC](https://www.ruby-forum.com/t/bug-1-9-lack-consistency-in-hash-iteration/159458/7 "2009-02-06T16:57:23Z")

</div>

e$B1sF#$G$9!#e(B

2009/02/06 1:01 Yusuke ENDOH [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> e$BF1$8MWAG$rJ#?t2se(B yield e$B$9$k2DG=@-$,$"$j$^$9!#e(B
> 
> $ ./ruby -e ‘h = {1=\>1,2=\>2}; h.each {|x| p x; h.delete(2) }’  
> [1, 1]  
> [1, 1]
> 
> e$B$9$0$K$O2r7h:v$,;W$$$D$+$J$$$N$G!"$A$g$C$H9M$($^$9!#e(B

e$B8=\>u$Ne(B st\_foreach e$B$@$H!“e(BHash  
e$B$N%$%F%l!\<%HCf$K%O%C%7%e$NMWAG$r:o=|$9$k$He(B  
e$B:o=|$5$l$F$$$J$$MWAG$G$b\<h$j$3$$9$3$H$,$”$k$h$&$G$9!#e(B

a = (1…3).map do |i|  
x = Object.new  
def x.hash; 1; end  
x  
end

h = {}  
a.each {|x| h[x] = true }

p h #=\> {#Object:0x81fcdb0=\>true, #Object:0x81fcce8=\>true,  
#Object:0x81fcc5c=\>true}

h.each do |x|  
p x  
h.delete(a[0])  
h.delete(a[1])  
end  
#=\> [#Object:0x81fcdb0, true]  
e$B$@$1$7$+=P$J$$!"e(B[#Object:0x81fcc5c=\>true, true] e$B$O=P$k$O$:e(B

p h #=\> {#Object:0x81fcc5c=\>true}

e$B860x$O%$%F%l!\<%H$N=\*N;\>r7o$,@5$7$/$J$$$?$a$G$9$,!"e(BHash  
e$B$N=g=x$re(B  
e$B%k!\<%W9=B$$G4IM}$7$F$$$k8B$j2r7h$G$-$J$$$h$&$J5$$,$7$^$7$?!#e(B

e$B=g=x$rAPJ}8~%j%9%H$G4IM}$9$l$PD\>$j$^$7$?!#e(B

# Index: include/ruby/st.h

— include/ruby/st.h (revision 22101)  
+++ include/ruby/st.h (working copy)  
@@ -75,7 +75,7 @@  
#endif  
st\_index\_t num\_entries : ST\_INDEX\_BITS - 1;  
struct st\_table\_entry \*\*bins;

- struct st\_table\_entry \*head;

- struct st\_table\_entry \*head, \*back;  
};

# #define st\_is\_member(table,key) st\_lookup(table,key,(st\_data\_t \*)0) Index: st.c

— st.c (revision 22101)  
+++ st.c (working copy)  
@@ -176,6 +176,7 @@  
tbl-\>num\_bins = size;  
tbl-\>bins = (st\_table\_entry \*_)Calloc(size,  
sizeof(st\_table\_entry_));  
tbl-\>head = 0;

- tbl-\>back = 0;

- table-\>back = 0;  
}

void  
@@ -335,7 +337,7 @@

#define ADD\_DIRECT(table, key, value, hash\_val, bin\_pos)  
do {\

- st\_table\_entry \*entry, \*head;\

- st\_table\_entry \*entry;  
if (table-\>num\_entries/(table-\>num\_bins) \> ST\_DEFAULT\_MAX\_DENSITY)  
{  
rehash(table);  
bin\_pos = hash\_val % table-\>num\_bins;  
@@ -347,13 +349,14 @@  
entry-\>key = key;  
entry-\>record = value;  
entry-\>next = table-\>bins[bin\_pos];\

- if ((head = table-\>head) != 0) {\
- entry-\>fore = head;\
- (entry-\>back = head-\>back)-\>fore = entry;\
- head-\>back = entry;\

- if (table-\>head != 0) {\
- entry-\>fore = 0;\
- (entry-\>back = table-\>back)-\>fore = entry;\
- table-\>back = entry;  
}  
else {\

- table-\>head = entry-\>fore = entry-\>back = entry;\

- table-\>head = table-\>back = entry;\
- entry-\>fore = entry-\>back = 0;  
}  
table-\>bins[bin\_pos] = entry;  
table-\>num\_entries++;  
@@ -455,7 +458,7 @@  
hash\_val = ptr-\>hash % new\_num\_bins;  
ptr-\>next = new\_bins[hash\_val];  
new\_bins[hash\_val] = ptr;

- } while ((ptr = ptr-\>fore) != table-\>head);

- } while ((ptr = ptr-\>fore) != 0);  
}  
}

@@ -502,10 +505,8 @@  
entry-\>back = prev;  
\*tail = prev = entry;  
tail = &entry-\>fore;

- } while ((ptr = ptr-\>fore) != old\_table-\>head);
- entry = new\_table-\>head;
- entry-\>back = prev;
- \*tail = entry;

- } while ((ptr = ptr-\>fore) != 0);

- new\_table-\>back = prev;  
}

#define REMOVE\_ENTRY(table, ptr) do   
{ \

- if (ptr == ptr-\>fore) { \

- if (ptr-\>fore == 0 && ptr-\>back == 0) {   
table-\>head = 0; \
- 

```
 table->back = 0; \

```

}   
else {   
st\_table\_entry \*fore = ptr-\>fore, \*back = ptr-\>back; \

- 

```
 fore->back = back; \

```

- 

```
 back->fore = fore; \

```

- 

```
 if (fore) fore->back = back; \

```

- 

```
 if (back) back->fore = fore; \
 if (ptr == table->head) table->head = fore; \

```

- 

```
 if (ptr == table->back) table->back = back; \

```

}   
table-\>num\_entries–;   
} while (0)  
@@ -613,7 +616,7 @@  
{  
st\_table\_entry \*ptr, \*\*last, \*tmp;  
enum st\_retval retval;

- int i, end;

- int i;

- 

```
 end = ptr->fore == table->head;
 retval = (*func)(ptr->key, ptr->record, arg);
 switch (retval) {
   case ST_CHECK: /* check if hash is modified during iteration 

```

\*/  
@@ -683,7 +685,7 @@  
}  
}  
}

- } while (!end && table-\>head);

- } while (ptr && table-\>head);  
}  
return 0;  
}  
@@ -694,7 +696,7 @@  
{  
st\_table\_entry \*ptr, \*\*last, \*tmp;  
enum st\_retval retval;

- int i, end;

- int i;

- 

```
 end = ptr == table->head;
 retval = (*func)(ptr->key, ptr->record, arg, 0);
 switch (retval) {
   case ST_CHECK: /* check if hash is modified during iteration 

```

\*/  
@@ -766,7 +767,7 @@  
free(tmp);  
table-\>num\_entries–;  
}

- } while (!end && table-\>head);

- } while (ptr && table-\>head);  
}  
return 0;  
}