<s>
The	O
Da	B-Application
Vinci	I-Application
Machine	I-Application
,	O
also	O
called	O
the	O
Multi	B-Application
Language	I-Application
Virtual	I-Application
Machine	I-Application
,	O
was	O
a	O
Sun	O
Microsystems	O
project	O
aiming	O
to	O
prototype	O
the	O
extension	O
of	O
the	O
Java	B-Language
Virtual	I-Language
Machine	I-Language
(	O
JVM	B-Language
)	O
to	O
add	O
support	O
for	O
dynamic	B-Language
languages	I-Language
.	O
</s>
<s>
It	O
was	O
already	O
possible	O
to	O
run	O
dynamic	B-Language
languages	I-Language
on	O
top	O
of	O
the	O
JVM	B-Language
,	O
but	O
the	O
goal	O
is	O
to	O
ease	O
new	O
dynamic	B-Language
language	I-Language
implementations	O
and	O
increase	O
their	O
performance	O
.	O
</s>
<s>
This	O
project	O
was	O
the	O
reference	O
implementation	O
of	O
JSR	B-Application
292	I-Application
(	O
Supporting	O
Dynamically	O
Typed	O
Languages	O
on	O
the	O
Java	B-Device
Platform	I-Device
)	O
.	O
</s>
<s>
Prior	O
to	O
Java	B-Device
7	O
,	O
the	O
Java	B-Language
Virtual	I-Language
Machine	I-Language
had	O
no	O
built-in	O
support	O
for	O
dynamically	O
typed	O
languages	O
:	O
</s>
<s>
The	O
existing	O
JVM	B-Language
instruction	I-Language
set	I-Language
is	O
statically	O
typed	O
.	O
</s>
<s>
JVM	B-Language
has	O
limited	O
support	O
for	O
dynamically	O
modifying	O
existing	O
classes	O
and	O
methods	O
.	O
</s>
<s>
It	O
currently	O
works	O
only	O
in	O
a	O
debugging	B-Language
environment	I-Language
.	O
</s>
<s>
JSR	B-Application
292	I-Application
(	O
Supporting	O
Dynamically	O
Typed	O
Languages	O
on	O
the	O
Java	B-Device
Platform	I-Device
)	O
proposes	O
to	O
:	O
</s>
<s>
add	O
a	O
new	O
invokedynamic	O
instruction	O
at	O
the	O
JVM	B-Language
level	O
,	O
to	O
allow	O
method	O
invocation	O
relying	O
on	O
dynamic	O
type	O
checking	O
,	O
</s>
<s>
Following	O
the	O
success	O
of	O
the	O
JRuby	B-Language
Java	B-Device
implementation	O
,	O
the	O
Da	O
Vinci	O
project	O
was	O
started	O
at	O
the	O
end	O
of	O
January	O
2008	O
.	O
</s>
<s>
The	O
capabilities	O
experimented	O
by	O
Da	O
Vinci	O
were	O
planned	O
to	O
be	O
added	O
to	O
Java	B-Device
7	O
.	O
</s>
<s>
It	O
aims	O
to	O
prototype	O
this	O
JSR	B-Language
,	O
but	O
also	O
other	O
lower-priority	O
extensions	O
.	O
</s>
<s>
The	O
first	O
working	O
prototype	O
,	O
developed	O
as	O
a	O
patch	O
on	O
OpenJDK	B-Language
,	O
was	O
announced	O
and	O
made	O
available	O
on	O
end	O
of	O
August	O
2008	O
.	O
</s>
<s>
Since	O
then	O
,	O
the	O
JRuby	B-Language
team	O
has	O
successfully	O
wired	O
dynamic	O
invocation	O
in	O
their	O
codebase	O
.	O
</s>
<s>
Dynamic	O
invocation	O
shipped	O
with	O
the	O
1.1.5	O
release	O
,	O
and	O
will	O
be	O
disabled	O
on	O
JVMs	B-Language
without	O
invokedynamic	O
capabilities	O
.	O
</s>
<s>
Since	O
then	O
,	O
the	O
project	O
has	O
been	O
integrated	O
in	O
the	O
JDK	O
7	O
codebase	O
and	O
then	O
integrated	O
in	O
the	O
Java	B-Device
7	O
release	O
.	O
</s>
<s>
Dynamic	O
invocation	O
is	O
built	O
on	O
the	O
fact	O
that	O
,	O
even	O
if	O
Java	B-Device
is	O
a	O
strongly	O
static	O
language	O
at	O
the	O
language	O
level	O
,	O
the	O
type	O
information	O
is	O
much	O
less	O
prevalent	O
at	O
the	O
bytecode	B-Language
level	O
.	O
</s>
<s>
However	O
,	O
dynamic	B-Language
languages	I-Language
implementations	O
need	O
to	O
be	O
able	O
to	O
use	O
just-in-time	O
compilation	O
(	O
rather	O
than	O
reflection	B-Language
)	O
to	O
achieve	O
good	O
performance	O
,	O
and	O
so	O
to	O
compile	O
scripts	O
to	O
bytecode	B-Language
at	O
runtime	O
.	O
</s>
<s>
To	O
be	O
allowed	O
to	O
be	O
run	O
by	O
the	O
Java	B-Language
Virtual	I-Language
Machine	I-Language
,	O
these	O
bytecodes	O
must	O
be	O
verified	O
prior	O
to	O
the	O
execution	O
,	O
and	O
the	O
verifier	O
check	O
that	O
the	O
types	O
are	O
static	O
throughout	O
the	O
code	O
.	O
</s>
<s>
This	O
not	O
only	O
uses	O
a	O
lot	O
of	O
memory	O
,	O
but	O
also	O
fills	O
a	O
memory	O
area	O
called	O
Metaspace	O
(	O
Permanent	O
Generation	O
prior	O
to	O
Java	B-Device
8	O
)	O
,	O
a	O
part	O
of	O
the	O
heap	B-General_Concept
used	O
by	O
the	O
JVM	B-Language
to	O
store	O
information	O
about	O
classes	O
.	O
</s>
<s>
Memory	O
used	O
in	O
this	O
area	O
is	O
almost	O
never	O
garbage	B-General_Concept
collected	I-General_Concept
because	O
it	O
stores	O
immutable	O
data	O
in	O
the	O
context	O
of	O
Java	B-Device
programs	O
;	O
and	O
because	O
of	O
that	O
,	O
dynamic	B-Language
languages	I-Language
implementations	O
can	O
only	O
compile	O
a	O
small	O
part	O
of	O
the	O
scripts	O
.	O
</s>
<s>
JSR	B-Application
292	I-Application
proposes	O
to	O
:	O
</s>
<s>
provide	O
the	O
new	O
invokedynamic	O
bytecode	B-Language
which	O
allows	O
the	O
JVM	B-Language
to	O
optimize	O
calls	O
of	O
this	O
kind	O
.	O
</s>
