<s>
In	O
computing	O
,	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
is	O
a	O
component	O
of	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
and	O
the	O
retired	O
Carbon	B-Operating_System
API	I-Operating_System
allowing	O
programs	O
to	O
perform	O
work	O
across	O
multiple	O
preemptively	B-Operating_System
scheduled	I-Operating_System
threads	O
of	O
execution	O
.	O
</s>
<s>
Multiprocessing	B-Operating_System
Services	I-Operating_System
was	O
introduced	O
in	O
1996	O
with	O
the	O
release	O
of	O
System	O
7.5.3	O
.	O
</s>
<s>
Multiprocessing	B-Operating_System
Services	I-Operating_System
2.0	O
,	O
introduced	O
in	O
Mac	B-Application
OS	I-Application
8.6	O
,	O
is	O
a	O
backwards-compatible	O
major	O
release	O
that	O
increases	O
the	O
level	O
of	O
integration	O
preemptive	O
tasks	O
have	O
with	O
the	O
rest	O
of	O
the	O
system	O
.	O
</s>
<s>
Multiprocessing	B-Operating_System
Services	I-Operating_System
2.1	O
,	O
introduced	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
9	I-Operating_System
,	O
adds	O
support	O
for	O
devices	O
with	O
more	O
than	O
1	O
GB	O
of	O
RAM	O
.	O
</s>
<s>
In	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
,	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
is	O
not	O
the	O
only	O
threading	O
mechanism	O
;	O
cooperatively	O
scheduled	O
threads	O
can	O
be	O
created	O
with	O
the	O
Thread	O
Manager	O
.	O
</s>
<s>
While	O
applications	O
using	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
have	O
their	O
threads	O
preemptively	B-Operating_System
scheduled	I-Operating_System
,	O
the	O
application	O
as	O
a	O
whole	O
is	O
still	O
cooperatively	O
scheduled	O
with	O
other	O
running	O
applications	O
.	O
</s>
<s>
Non-Multiprocessing	O
Services	O
tasks	O
remain	O
scheduled	O
on	O
a	O
single	O
processor	O
,	O
and	O
tasks	O
using	O
the	O
Macintosh	B-Device
Toolbox	I-Device
cannot	O
be	O
preemptively	B-Operating_System
scheduled	I-Operating_System
.	O
</s>
<s>
When	O
a	O
process	O
uses	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
,	O
in	O
addition	O
to	O
the	O
preemptive	O
tasks	O
it	O
creates	O
,	O
an	O
additional	O
task	O
exists	O
,	O
deth	O
,	O
which	O
waits	O
for	O
other	O
tasks	O
created	O
by	O
the	O
process	O
to	O
terminate	O
and	O
cleans	O
up	O
their	O
resources	O
when	O
they	O
do	O
.	O
</s>
<s>
In	O
macOS	B-Application
,	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
is	O
implemented	O
using	O
POSIX	B-Operating_System
threads	I-Operating_System
.	O
</s>
<s>
Applications	O
using	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
are	O
preemptively	B-Operating_System
scheduled	I-Operating_System
with	O
other	O
tasks	O
running	O
on	O
the	O
system	O
.	O
</s>
<s>
Multiprocessing	O
tasks	O
are	O
distinct	O
from	O
Mach	B-Operating_System
tasks	O
.	O
</s>
<s>
In	O
OS	B-Operating_System
X	I-Operating_System
10.8	I-Operating_System
,	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
was	O
deprecated	O
with	O
the	O
rest	O
of	O
Carbon	B-Operating_System
,	O
with	O
Grand	B-Operating_System
Central	I-Operating_System
Dispatch	I-Operating_System
suggested	O
as	O
a	O
replacement	O
.	O
</s>
<s>
In	O
macOS	B-Device
10.15	I-Device
,	O
support	O
for	O
Multiprocessing	B-Operating_System
Services	I-Operating_System
ended	O
with	O
the	O
removal	O
of	O
32-bit	O
application	O
support	O
,	O
which	O
included	O
all	O
Carbon	B-Operating_System
applications	O
.	O
</s>
