<s>
Chainer	B-Algorithm
is	O
an	O
open	B-Application
source	I-Application
deep	B-Algorithm
learning	I-Algorithm
framework	O
written	O
purely	O
in	O
Python	B-Language
on	O
top	O
of	O
NumPy	B-Application
and	O
CuPy	B-Application
Python	B-Language
libraries	O
.	O
</s>
<s>
Chainer	B-Algorithm
is	O
notable	O
for	O
its	O
early	O
adoption	O
of	O
"	O
define-by-run	O
"	O
scheme	O
,	O
as	O
well	O
as	O
its	O
performance	O
on	O
large	O
scale	O
systems	O
.	O
</s>
<s>
Furthermore	O
,	O
in	O
2017	O
,	O
it	O
was	O
listed	O
by	O
KDnuggets	O
in	O
top	O
10	O
open	B-Application
source	I-Application
machine	O
learning	O
Python	B-Language
projects	O
.	O
</s>
<s>
In	O
December	O
2019	O
,	O
Preferred	O
Networks	O
announced	O
the	O
transition	O
of	O
its	O
development	O
effort	O
from	O
Chainer	B-Algorithm
to	O
PyTorch	B-Algorithm
and	O
it	O
will	O
only	O
provide	O
maintenance	O
patches	O
after	O
releasing	O
v7	O
.	O
</s>
<s>
Chainer	B-Algorithm
was	O
the	O
first	O
deep	B-Algorithm
learning	I-Algorithm
framework	O
to	O
introduce	O
the	O
define-by-run	O
approach	O
.	O
</s>
<s>
Theano	B-Algorithm
and	O
TensorFlow	B-Language
are	O
among	O
the	O
notable	O
frameworks	O
that	O
took	O
this	O
approach	O
.	O
</s>
<s>
If	O
the	O
network	O
has	O
complicated	O
control	O
flows	O
such	O
as	O
conditionals	B-Language
and	O
loops	O
,	O
in	O
the	O
define-and-run	O
approach	O
,	O
specially	O
designed	O
operations	O
for	O
such	O
constructs	O
are	O
needed	O
.	O
</s>
<s>
This	O
flexibility	O
is	O
especially	O
useful	O
to	O
implement	O
recurrent	B-Algorithm
neural	I-Algorithm
networks	I-Algorithm
.	O
</s>
<s>
In	O
the	O
define-by-run	O
approach	O
,	O
you	O
can	O
just	O
suspend	O
the	O
calculation	O
with	O
the	O
language	O
's	O
built-in	O
debugger	B-Application
and	O
inspect	O
the	O
data	O
that	O
flows	O
on	O
your	O
code	O
of	O
the	O
network	O
.	O
</s>
<s>
Define-by-run	O
has	O
gained	O
popularity	O
since	O
the	O
introduction	O
by	O
Chainer	B-Algorithm
and	O
is	O
now	O
implemented	O
in	O
many	O
other	O
frameworks	O
,	O
including	O
PyTorch	B-Algorithm
and	O
TensorFlow	B-Language
.	O
</s>
<s>
Chainer	B-Algorithm
has	O
four	O
extension	O
libraries	O
,	O
ChainerMN	O
,	O
ChainerRL	O
,	O
ChainerCV	O
and	O
ChainerUI	O
.	O
</s>
<s>
ChainerMN	O
enables	O
Chainer	B-Algorithm
to	O
be	O
used	O
on	O
multiple	O
GPUs	O
with	O
performance	O
significantly	O
faster	O
than	O
other	O
deep	B-Algorithm
learning	I-Algorithm
frameworks	O
.	O
</s>
<s>
A	O
supercomputer	O
running	O
Chainer	B-Algorithm
on	O
1024	O
GPUs	O
processed	O
90	O
epochs	O
of	O
ImageNet	B-General_Concept
dataset	O
on	O
ResNet-50	O
network	O
in	O
15	O
minutes	O
,	O
which	O
is	O
four	O
times	O
faster	O
than	O
the	O
previous	O
record	O
held	O
by	O
Facebook	O
.	O
</s>
<s>
Chainer	B-Algorithm
is	O
used	O
as	O
the	O
framework	O
for	O
PaintsChainer	O
,	O
a	O
service	O
which	O
does	O
automatic	O
colorization	O
of	O
black	O
and	O
white	O
,	O
line	O
only	O
,	O
draft	O
drawings	O
with	O
minimal	O
user	O
input	O
.	O
</s>
