<s>
A	O
distributed	B-Operating_System
algorithm	I-Operating_System
is	O
an	O
algorithm	O
designed	O
to	O
run	O
on	O
computer	B-Architecture
hardware	I-Architecture
constructed	O
from	O
interconnected	O
processors	B-General_Concept
.	O
</s>
<s>
Distributed	B-Operating_System
algorithms	I-Operating_System
are	O
used	O
in	O
different	O
application	O
areas	O
of	O
distributed	B-Architecture
computing	I-Architecture
,	O
such	O
as	O
telecommunications	O
,	O
scientific	O
computing	O
,	O
distributed	B-Architecture
information	I-Architecture
processing	I-Architecture
,	O
and	O
real-time	O
process	O
control	O
.	O
</s>
<s>
Standard	O
problems	O
solved	O
by	O
distributed	B-Operating_System
algorithms	I-Operating_System
include	O
leader	B-Operating_System
election	I-Operating_System
,	O
consensus	B-Operating_System
,	O
distributed	O
search	B-Application
,	O
spanning	O
tree	O
generation	O
,	O
mutual	B-Operating_System
exclusion	I-Operating_System
,	O
and	O
resource	B-Algorithm
allocation	I-Algorithm
.	O
</s>
<s>
Distributed	B-Operating_System
algorithms	I-Operating_System
are	O
a	O
sub-type	O
of	O
parallel	B-Operating_System
algorithm	I-Operating_System
,	O
typically	O
executed	O
concurrently	B-Operating_System
,	O
with	O
separate	O
parts	O
of	O
the	O
algorithm	O
being	O
run	O
simultaneously	O
on	O
independent	O
processors	B-General_Concept
,	O
and	O
having	O
limited	O
information	O
about	O
what	O
the	O
other	O
parts	O
of	O
the	O
algorithm	O
are	O
doing	O
.	O
</s>
<s>
One	O
of	O
the	O
major	O
challenges	O
in	O
developing	O
and	O
implementing	O
distributed	B-Operating_System
algorithms	I-Operating_System
is	O
successfully	O
coordinating	O
the	O
behavior	O
of	O
the	O
independent	O
parts	O
of	O
the	O
algorithm	O
in	O
the	O
face	O
of	O
processor	O
failures	O
and	O
unreliable	O
communications	O
links	O
.	O
</s>
<s>
The	O
choice	O
of	O
an	O
appropriate	O
distributed	B-Operating_System
algorithm	I-Operating_System
to	O
solve	O
a	O
given	O
problem	O
depends	O
on	O
both	O
the	O
characteristics	O
of	O
the	O
problem	O
,	O
and	O
characteristics	O
of	O
the	O
system	O
the	O
algorithm	O
will	O
run	O
on	O
such	O
as	O
the	O
type	O
and	O
probability	O
of	O
processor	O
or	O
link	O
failures	O
,	O
the	O
kind	O
of	O
inter-process	B-Operating_System
communication	I-Operating_System
that	O
can	O
be	O
performed	O
,	O
and	O
the	O
level	O
of	O
timing	O
synchronization	O
between	O
separate	O
processes	O
.	O
</s>
<s>
An	O
atomic	B-Operating_System
commit	I-Operating_System
is	O
an	O
operation	O
where	O
a	O
set	O
of	O
distinct	O
changes	O
is	O
applied	O
as	O
a	O
single	O
operation	O
.	O
</s>
<s>
If	O
the	O
atomic	B-Operating_System
commit	I-Operating_System
succeeds	O
,	O
it	O
means	O
that	O
all	O
the	O
changes	O
have	O
been	O
applied	O
.	O
</s>
<s>
If	O
there	O
is	O
a	O
failure	O
before	O
the	O
atomic	B-Operating_System
commit	I-Operating_System
can	O
be	O
completed	O
,	O
the	O
"	O
commit	O
"	O
is	O
aborted	O
and	O
no	O
changes	O
will	O
be	O
applied	O
.	O
</s>
<s>
Algorithms	O
for	O
solving	O
the	O
atomic	B-Operating_System
commit	I-Operating_System
problem	O
include	O
the	O
two-phase	B-General_Concept
commit	I-General_Concept
protocol	I-General_Concept
and	O
the	O
three-phase	O
commit	O
protocol	O
.	O
</s>
<s>
Consensus	B-Operating_System
algorithms	I-Operating_System
try	O
to	O
solve	O
the	O
problem	O
of	O
a	O
number	O
of	O
processes	O
agreeing	O
on	O
a	O
common	O
decision	O
.	O
</s>
<s>
More	O
precisely	O
,	O
a	O
Consensus	B-Operating_System
protocol	O
must	O
satisfy	O
the	O
four	O
formal	O
properties	O
below	O
.	O
</s>
<s>
Common	O
algorithms	O
for	O
solving	O
consensus	B-Operating_System
are	O
the	O
Paxos	B-Operating_System
algorithm	I-Operating_System
and	O
the	O
Raft	B-Operating_System
algorithm	I-Operating_System
.	O
</s>
<s>
Leader	B-Operating_System
election	I-Operating_System
is	O
the	O
process	O
of	O
designating	O
a	O
single	O
process	O
as	O
the	O
organizer	O
of	O
some	O
task	O
distributed	O
among	O
several	O
computers	O
(	O
nodes	O
)	O
.	O
</s>
<s>
After	O
a	O
leader	B-Operating_System
election	I-Operating_System
algorithm	O
has	O
been	O
run	O
,	O
however	O
,	O
each	O
node	O
throughout	O
the	O
network	O
recognizes	O
a	O
particular	O
,	O
unique	O
node	O
as	O
the	O
task	O
leader	O
.	O
</s>
<s>
Reliable	B-Operating_System
broadcast	I-Operating_System
is	O
a	O
communication	O
primitive	O
in	O
distributed	B-Architecture
systems	I-Architecture
.	O
</s>
<s>
A	O
reliable	B-Operating_System
broadcast	I-Operating_System
is	O
defined	O
by	O
the	O
following	O
properties	O
:	O
</s>
<s>
A	O
reliable	B-Operating_System
broadcast	I-Operating_System
can	O
have	O
sequential	O
,	O
causal	O
or	O
total	O
ordering	O
.	O
</s>
