<s>
Distributed	B-General_Concept
garbage	I-General_Concept
collection	I-General_Concept
(	O
DGC	O
)	O
in	O
computing	O
is	O
a	O
particular	O
case	O
of	O
garbage	B-General_Concept
collection	I-General_Concept
where	O
a	O
remote	O
client	O
can	O
hold	O
references	O
to	O
an	O
object	O
.	O
</s>
<s>
DGC	O
uses	O
some	O
combination	O
of	O
the	O
classical	O
garbage	B-General_Concept
collection	I-General_Concept
(	O
GC	O
)	O
techniques	O
,	O
tracing	O
and	O
reference	B-General_Concept
counting	I-General_Concept
.	O
</s>
<s>
It	O
has	O
to	O
cooperate	O
with	O
local	O
garbage	B-General_Concept
collectors	I-General_Concept
in	O
each	O
process	B-Operating_System
in	O
order	O
to	O
keep	O
global	O
counts	O
,	O
or	O
to	O
globally	O
trace	O
accessibility	O
of	O
data	O
.	O
</s>
<s>
In	O
general	O
,	O
remote	O
processors	O
do	O
not	O
have	O
to	O
know	O
about	O
internal	O
counting	O
or	O
tracing	O
in	O
a	O
given	O
process	B-Operating_System
,	O
and	O
the	O
relevant	O
information	O
is	O
stored	O
in	O
interfaces	O
associated	O
with	O
each	O
process	B-Operating_System
.	O
</s>
<s>
As	O
a	O
cheap	O
way	O
of	O
avoiding	O
DGC	O
algorithms	O
,	O
one	O
can	O
rely	O
on	O
a	O
time	O
lease	O
–	O
set	O
or	O
configured	O
on	O
the	O
remote	O
object	O
;	O
it	O
is	O
the	O
stub	B-Operating_System
's	O
task	O
to	O
periodically	O
renew	O
the	O
lease	O
on	O
the	O
remote	O
object	O
.	O
</s>
<s>
If	O
the	O
lease	O
has	O
expired	O
,	O
the	O
server	O
process	B-Operating_System
(	O
the	O
process	B-Operating_System
owning	O
the	O
remote	O
object	O
)	O
can	O
safely	O
assume	O
that	O
either	O
the	O
client	O
is	O
no	O
longer	O
interested	O
in	O
the	O
object	O
,	O
or	O
that	O
a	O
network	B-Algorithm
partition	I-Algorithm
or	O
crash	B-General_Concept
obstructed	O
lease	O
renewal	O
,	O
in	O
which	O
case	O
it	O
is	O
"	O
hard	O
luck	O
"	O
for	O
the	O
client	O
if	O
it	O
is	O
in	O
fact	O
still	O
interested	O
.	O
</s>
<s>
Hence	O
,	O
if	O
there	O
is	O
only	O
a	O
single	O
reference	O
to	O
the	O
remote	O
object	O
on	O
the	O
server	O
representing	O
a	O
remote	O
reference	O
from	O
that	O
client	O
,	O
that	O
reference	O
can	O
be	O
dropped	O
,	O
which	O
will	O
mean	O
that	O
the	O
local	O
garbage	B-General_Concept
collector	I-General_Concept
on	O
the	O
server	O
will	O
garbage-collect	O
the	O
object	O
at	O
some	O
future	O
point	O
in	O
time	O
.	O
</s>
