<s>
The	O
spinning	B-Operating_System
pinwheel	I-Operating_System
is	O
a	O
type	O
of	O
throbber	O
or	O
variation	O
of	O
the	O
mouse	O
pointer	B-Device
used	O
in	O
Apple	O
's	O
macOS	B-Application
to	O
indicate	O
that	O
an	O
application	B-Application
is	O
busy	O
.	O
</s>
<s>
Officially	O
,	O
the	O
macOS	B-Application
Human	B-Application
Interface	I-Application
Guidelines	O
refers	O
to	O
it	O
as	O
the	O
spinning	O
wait	O
cursor	O
,	O
but	O
it	O
is	O
also	O
known	O
by	O
other	O
names	O
.	O
</s>
<s>
These	O
include	O
but	O
are	O
not	O
limited	O
to	O
the	O
spinning	B-Operating_System
beach	I-Operating_System
ball	I-Operating_System
,	O
the	O
spinning	B-Operating_System
wheel	I-Operating_System
of	I-Operating_System
death	I-Operating_System
,	O
the	O
spinning	B-Operating_System
beachball	I-Operating_System
of	I-Operating_System
death	I-Operating_System
,	O
or	O
the	O
Ferris	O
wheel	O
of	O
death	O
.	O
</s>
<s>
A	O
wristwatch	O
was	O
the	O
first	O
wait	O
cursor	O
in	O
early	O
versions	O
of	O
the	O
classic	B-Application
Mac	I-Application
OS	I-Application
.	O
</s>
<s>
Apple	O
's	O
HyperCard	B-Application
first	O
popularised	O
animated	O
cursors	O
,	O
including	O
a	O
black-and-white	O
spinning	O
quartered	O
circle	O
resembling	O
a	O
beach	O
ball	O
.	O
</s>
<s>
The	O
beach-ball	O
cursor	O
was	O
also	O
adopted	O
to	O
indicate	O
running	O
script	O
code	O
in	O
the	O
HyperTalk-like	O
AppleScript	B-Application
.	O
</s>
<s>
The	O
cursors	O
could	O
be	O
advanced	O
by	O
repeated	O
HyperTalk	B-Language
invocations	O
of	O
"	O
set	O
cursor	O
to	O
busy	O
"	O
.	O
</s>
<s>
Other	O
applications	O
provided	O
their	O
own	O
theme-appropriate	O
custom	O
cursors	O
,	O
such	O
as	O
a	O
revolving	O
Yin	O
Yang	O
symbol	O
,	O
Fetch	B-Application
's	O
running	O
dog	O
,	O
Retrospect	B-Operating_System
's	O
spinning	O
tape	O
,	O
and	O
Pro	B-Application
Tools	I-Application
 '	O
tapping	O
fingers	O
.	O
</s>
<s>
Apple	O
provided	O
standard	O
interfaces	O
for	O
animating	O
cursors	O
:	O
originally	O
the	O
Cursor	O
Utilities	O
(	O
SpinCursor	O
,	O
RotateCursor	O
)	O
and	O
,	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
8	I-Operating_System
and	O
later	O
,	O
the	O
Appearance	B-Operating_System
Manager	I-Operating_System
(	O
SetAnimatedThemeCursor	O
)	O
.	O
</s>
<s>
NeXTStep	B-Application
1.0	I-Application
used	O
a	O
monochrome	O
icon	O
resembling	O
a	O
spinning	O
magneto-optical	B-Device
disk	I-Device
.	O
</s>
<s>
Some	O
NeXT	B-Device
computers	I-Device
included	O
an	O
optical	O
drive	O
which	O
was	O
often	O
slower	O
than	O
a	O
magnetic	B-Device
hard	I-Device
drive	I-Device
and	O
so	O
was	O
a	O
common	O
reason	O
for	O
the	O
wait	O
cursor	O
to	O
appear	O
.	O
</s>
<s>
When	O
color	O
support	O
was	O
added	O
in	O
NeXTStep	B-Application
2.0	O
,	O
color	O
versions	O
of	O
all	O
icons	O
were	O
added	O
.	O
</s>
<s>
The	O
wait	O
cursor	O
was	O
updated	O
to	O
reflect	O
the	O
bright	O
rainbow	O
surface	O
of	O
these	O
removable	O
disks	O
,	O
and	O
that	O
icon	O
remained	O
even	O
when	O
later	B-Device
machines	I-Device
began	O
using	O
hard	B-Device
disk	I-Device
drives	I-Device
as	O
primary	O
storage	O
.	O
</s>
<s>
Contemporary	O
CD	B-Device
Rom	I-Device
drives	O
were	O
even	O
slower	O
(	O
at	O
1x	O
,	O
150	O
kbit/s	O
)	O
.	O
</s>
<s>
With	O
the	O
arrival	O
of	O
Mac	B-Application
OS	I-Application
X	O
the	O
wait	O
cursor	O
was	O
often	O
called	O
the	O
"	O
spinning	B-Operating_System
beach	I-Operating_System
ball	I-Operating_System
"	O
in	O
the	O
press	O
,	O
presumably	O
by	O
authors	O
not	O
knowing	O
its	O
NeXT	O
history	O
or	O
relating	O
it	O
to	O
the	O
hypercard	B-Application
wait	O
cursor	O
.	O
</s>
<s>
The	O
two-dimensional	O
appearance	O
was	O
kept	O
essentially	O
unchanged	O
from	O
NeXT	O
to	O
Rhapsody/Mac	O
OS	O
X	O
Server	O
1.0	O
which	O
otherwise	O
had	O
a	O
user	B-Application
interface	I-Application
design	O
resembling	O
Mac	O
OS	O
8/Platinum	O
theme	O
,	O
and	O
through	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.0/Cheetah	I-Operating_System
and	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.1/Puma	I-Operating_System
,	O
which	O
introduced	O
the	O
Aqua	B-Application
user	I-Application
interface	I-Application
theme	O
.	O
</s>
<s>
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
10.2/Jaguar	I-Operating_System
gave	O
the	O
cursor	O
a	O
glossy	O
rounded	O
"	O
gumdrop	O
"	O
look	O
in	O
keeping	O
with	O
other	O
OS	B-Application
X	I-Application
interface	I-Application
elements	O
.	O
</s>
<s>
In	O
OS	B-Device
X	I-Device
10.10	I-Device
,	O
the	O
entire	O
pinwheel	O
rotates	O
(	O
previously	O
only	O
the	O
overlaying	O
translucent	O
layer	O
moved	O
)	O
.	O
</s>
<s>
With	O
OS	B-Operating_System
X	I-Operating_System
10.11	I-Operating_System
El	I-Operating_System
Capitan	I-Operating_System
the	O
spinning	O
wait-cursor	O
'	O
s	O
design	O
was	O
updated	O
.	O
</s>
<s>
It	O
now	O
has	O
less	O
shadowing	O
and	O
has	O
brighter	O
,	O
more	O
solid	O
colors	O
to	O
better	O
match	O
the	O
design	O
of	O
the	O
user	B-Application
interface	I-Application
.	O
</s>
<s>
This	O
changed	O
in	O
multitasking	O
operating	O
systems	O
such	O
as	O
System	B-Application
Software	I-Application
5	O
,	O
where	O
it	O
is	O
possible	O
to	O
switch	O
to	O
another	O
application	B-Application
and	O
continue	O
to	O
work	O
there	O
.	O
</s>
<s>
After	O
the	O
transition	O
to	O
Mac	B-Application
OS	I-Application
X	O
(	O
macOS	B-Application
)	O
,	O
Apple	O
narrowed	O
the	O
meaning	O
of	O
the	O
wait	O
cursor	O
.	O
</s>
<s>
The	O
display	O
of	O
the	O
wait	O
cursor	O
was	O
only	O
able	O
to	O
be	O
controlled	O
by	O
the	O
operating	O
system	O
,	O
not	O
by	O
the	O
application	B-Application
.	O
</s>
<s>
This	O
could	O
indicate	O
that	O
the	O
application	B-Application
was	O
in	O
an	O
infinite	B-Algorithm
loop	I-Algorithm
,	O
or	O
just	O
performing	O
a	O
lengthy	O
operation	O
and	O
ignoring	O
events	O
.	O
</s>
<s>
Each	O
application	B-Application
has	O
an	O
event	B-Operating_System
queue	I-Operating_System
that	O
receives	O
events	O
from	O
the	O
operating	O
system	O
(	O
for	O
example	O
,	O
key	O
presses	O
and	O
mouse	O
button	O
clicks	O
)	O
;	O
and	O
if	O
an	O
application	B-Application
takes	O
longer	O
than	O
2	O
seconds	O
to	O
process	O
the	O
events	O
in	O
its	O
event	B-Operating_System
queue	I-Operating_System
(	O
regardless	O
of	O
the	O
cause	O
)	O
,	O
the	O
operating	O
system	O
displays	O
the	O
wait	O
cursor	O
whenever	O
the	O
cursor	O
hovers	O
over	O
that	O
application	B-Application
's	O
windows	O
.	O
</s>
<s>
This	O
is	O
meant	O
to	O
indicate	O
that	O
the	O
application	B-Application
is	O
temporarily	O
unresponsive	O
,	O
a	O
state	O
from	O
which	O
the	O
application	B-Application
should	O
recover	O
.	O
</s>
<s>
It	O
also	O
may	O
indicate	O
that	O
all	O
or	O
part	O
of	O
the	O
application	B-Application
has	O
entered	O
an	O
unrecoverable	O
state	O
or	O
an	O
infinite	B-Algorithm
loop	I-Algorithm
.	O
</s>
<s>
During	O
this	O
time	O
the	O
user	O
may	O
be	O
prevented	O
from	O
closing	O
,	O
resizing	O
,	O
or	O
even	O
minimizing	O
the	O
windows	O
of	O
the	O
affected	O
application	B-Application
(	O
although	O
moving	O
the	O
window	O
is	O
still	O
possible	O
in	O
OS	O
X	O
,	O
as	O
well	O
as	O
previously	O
hidden	O
parts	O
of	O
the	O
window	O
being	O
usually	O
redrawn	O
,	O
even	O
when	O
the	O
application	B-Application
is	O
otherwise	O
unresponsive	O
)	O
.	O
</s>
<s>
While	O
one	O
application	B-Application
is	O
unresponsive	O
,	O
typically	O
other	O
applications	O
are	O
usable	O
.	O
</s>
<s>
If	O
operation	O
takes	O
long	O
,	O
the	O
application	B-Application
will	O
appear	O
unresponsive	O
.	O
</s>
<s>
Developers	O
may	O
prevent	O
this	O
by	O
using	O
separate	O
threads	B-Operating_System
for	O
lengthy	O
processing	O
,	O
allowing	O
the	O
application	B-Application
's	O
main	O
thread	B-Operating_System
to	O
continue	O
responding	O
to	O
external	O
events	O
.	O
</s>
<s>
However	O
,	O
this	O
greatly	O
increases	O
the	O
application	B-Application
complexity	O
.	O
</s>
<s>
Another	O
approach	O
is	O
to	O
divide	O
the	O
work	O
into	O
smaller	O
packets	O
and	O
use	O
or	O
Grand	B-Operating_System
Central	I-Operating_System
Dispatch	I-Operating_System
.	O
</s>
<s>
Bugs	B-Error_Name
in	O
applications	O
can	O
cause	O
them	O
to	O
stop	O
responding	O
to	O
events	O
;	O
for	O
instance	O
,	O
an	O
infinite	B-Algorithm
loop	I-Algorithm
or	O
a	O
deadlock	B-Operating_System
.	O
</s>
<s>
Problems	O
with	O
the	O
virtual	B-Architecture
memory	I-Architecture
system	O
—	O
such	O
as	O
slow	O
paging	B-Architecture
caused	O
by	O
a	O
spun-down	O
hard	B-Device
disk	I-Device
or	O
disk	O
read-errors	O
—	O
will	O
cause	O
the	O
wait	O
cursor	O
to	O
appear	O
across	O
multiple	O
applications	O
,	O
until	O
the	O
hard	B-Device
disk	I-Device
and	O
virtual	B-Architecture
memory	I-Architecture
system	O
recover	O
.	O
</s>
<s>
Instruments	O
is	O
an	O
application	B-Application
that	O
comes	O
with	O
the	O
Mac	B-Application
OS	I-Application
X	O
Developer	O
Tools	O
.	O
</s>
<s>
Each	O
time	O
an	O
application	B-Application
does	O
not	O
respond	O
and	O
the	O
spinning	O
wait	O
cursor	O
is	O
activated	O
,	O
Instruments	O
can	O
sample	O
the	O
process	O
to	O
determine	O
which	O
code	O
is	O
causing	O
the	O
application	B-Application
to	O
stop	O
responding	O
.	O
</s>
<s>
Apple	O
's	O
guidelines	O
suggest	O
that	O
developers	O
try	O
to	O
avoid	O
invoking	O
the	O
spinning	O
wait	O
cursor	O
,	O
and	O
instead	O
suggest	O
using	O
other	O
user	B-Application
interface	I-Application
indicators	O
,	O
such	O
as	O
an	O
asynchronous	O
progress	O
indicator	O
.	O
</s>
