<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
resource	B-General_Concept
contention	I-General_Concept
is	O
a	O
conflict	O
over	O
access	O
to	O
a	O
shared	B-General_Concept
resource	I-General_Concept
such	O
as	O
random	B-Architecture
access	I-Architecture
memory	I-Architecture
,	O
disk	B-Device
storage	I-Device
,	O
cache	B-General_Concept
memory	I-General_Concept
,	O
internal	O
buses	O
or	O
external	O
network	O
devices	O
.	O
</s>
<s>
A	O
resource	O
experiencing	O
ongoing	O
contention	O
can	O
be	O
described	O
as	O
oversubscribed	B-General_Concept
.	O
</s>
<s>
Resolving	O
resource	B-General_Concept
contention	I-General_Concept
problems	O
is	O
one	O
of	O
the	O
basic	O
functions	O
of	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Various	O
low-level	O
mechanisms	O
can	O
be	O
used	O
to	O
aid	O
this	O
,	O
including	O
locks	O
,	O
semaphores	B-Operating_System
,	O
mutexes	B-Operating_System
and	O
queues	B-Application
.	O
</s>
<s>
The	O
other	O
techniques	O
that	O
can	O
be	O
applied	O
by	O
the	O
operating	B-General_Concept
systems	I-General_Concept
include	O
intelligent	O
scheduling	O
,	O
application	O
mapping	O
decision	O
,	O
and	O
page	B-General_Concept
coloring	I-General_Concept
.	O
</s>
<s>
Access	O
to	O
resources	O
is	O
also	O
sometimes	O
regulated	O
by	O
queuing	O
;	O
in	O
the	O
case	O
of	O
computing	O
time	O
on	O
a	O
CPU	B-General_Concept
the	O
controlling	O
algorithm	O
of	O
the	O
task	B-General_Concept
queue	B-Application
is	O
called	O
a	O
scheduler	O
.	O
</s>
<s>
Failure	O
to	O
properly	O
resolve	O
resource	B-General_Concept
contention	I-General_Concept
problems	O
may	O
result	O
in	O
a	O
number	O
of	O
problems	O
,	O
including	O
deadlock	B-Operating_System
,	O
livelock	O
,	O
and	O
thrashing	B-General_Concept
.	O
</s>
<s>
Resource	B-General_Concept
contention	I-General_Concept
results	O
when	O
multiple	O
processes	B-Operating_System
attempt	O
to	O
use	O
the	O
same	O
shared	B-General_Concept
resource	I-General_Concept
.	O
</s>
<s>
Access	O
to	O
memory	O
areas	O
is	O
often	O
controlled	O
by	O
semaphores	B-Operating_System
,	O
which	O
allows	O
a	O
pathological	O
situation	O
called	O
a	O
deadlock	B-Operating_System
,	O
when	O
different	O
threads	B-Operating_System
or	O
processes	B-Operating_System
try	O
to	O
allocate	O
resources	O
already	O
allocated	O
by	O
each	O
other	O
.	O
</s>
<s>
A	O
deadlock	B-Operating_System
usually	O
leads	O
to	O
a	O
program	O
becoming	O
partially	O
or	O
completely	O
unresponsive	O
.	O
</s>
<s>
In	O
recent	O
years	O
,	O
research	O
on	O
the	O
contention	O
is	O
more	O
focused	O
on	O
the	O
resources	O
in	O
the	O
memory	B-General_Concept
hierarchy	I-General_Concept
,	O
e.g.	O
,	O
last-level	O
caches	B-General_Concept
,	O
front-side	O
bus	B-General_Concept
,	O
memory	O
socket	O
connection	O
.	O
</s>
