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Subject: Swtiching from Java 6 to Java 7 on Hadoop 2.2.0
From: Adam Kawa <kawa.adam@gmail.com>
To: "user@hadoop.apache.org" <user@hadoop.apache.org>
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Hi All!

We are about to upgrade the Java version of our Hadoop cluster (Hadoop
2.2.0). Just would like to ask about your recommendations and experience:

(A) Should we schedule a downtime of a whole cluster and then upgrade Java
everywhere (all Hadoop projects e.g. HDFS, YARN, Pig, Hive, Sqoop etc)

or

(B) Can we do a rolling upgrade to avoid downtime (this means that we would
run some nodes/projects on Java 6 talking to nodes/projects running on Java
7).

According to our initial research, (A) is generally recommended (because
some libraries can have incompatible APIs between their java 7 and java 6
versions e.g. Google Guavaa), but we are curious if there are any ways to
make (B) happen.

Cheers!
Adam

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Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Hi All!<div><br></div><div><div style=3D"font-family:arial=
,sans-serif;font-size:13px">We are about to upgrade the=C2=A0Java=C2=A0vers=
ion of our Hadoop cluster (Hadoop 2.2.0). Just would like to ask about your=
 recommendations and experience:</div><div style=3D"font-family:arial,sans-=
serif;font-size:13px"><br></div><div style=3D"font-family:arial,sans-serif;=
font-size:13px">(A) Should we schedule a downtime of a whole cluster and th=
en upgrade Java everywhere (all Hadoop projects e.g. HDFS, YARN, Pig, Hive,=
 Sqoop etc)</div><div style=3D"font-family:arial,sans-serif;font-size:13px"=
><br></div><div style=3D"font-family:arial,sans-serif;font-size:13px">or</d=
iv><div style=3D"font-family:arial,sans-serif;font-size:13px"><br></div><di=
v style=3D"font-family:arial,sans-serif;font-size:13px">(B) Can we do a rol=
ling upgrade to avoid downtime (this means that we would run some nodes/pro=
jects on Java 6 talking to nodes/projects running on Java 7).<br></div><div=
 style=3D"font-family:arial,sans-serif;font-size:13px"><br></div><div style=
=3D"font-family:arial,sans-serif;font-size:13px">According to our initial r=
esearch, (A) is generally recommended (because some libraries can have inco=
mpatible APIs between their java 7 and java 6 versions e.g. Google Guavaa),=
 but we are curious if there are any ways to make (B) happen.</div><div sty=
le=3D"font-family:arial,sans-serif;font-size:13px"><br></div><div style=3D"=
font-family:arial,sans-serif;font-size:13px">Cheers!</div></div><div style=
=3D"font-family:arial,sans-serif;font-size:13px">Adam</div></div>

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