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Date: Tue, 24 Feb 2015 18:02:04 +0000 (UTC)
From: Ravi Prakash <ravihoo@ymail.com>
Reply-To: Ravi Prakash <ravihoo@ymail.com>
To: "user@hadoop.apache.org" <user@hadoop.apache.org>
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Subject: Re: recoverLeaseInternal: why current leasehonder is forbidden to
 append the file?
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Hi Dmitry!
I suspect its because we don't want two streams from the same DFSClient to =
write to the same file. The Lease.holder is a simple string which correspon=
ds usually to DFSClient_<someid> .
HTH
Ravi.=20

     On Tuesday, February 24, 2015 12:12 AM, Dmitry Simonov <dimmoborgir@gm=
ail.com> wrote:
  =20

 Hello!
Could you please explain, why this check exists in class "org.apache.hadoop=
.hdfs.server.namenode.FSNamesystem", method "recoverLeaseInternal":

Lease leaseFile =3D leaseManager.getLeaseByPath(src);=C2=A0 =C2=A0 =C2=A0 =
=C2=A0 if (leaseFile !=3D null && leaseFile.equals(lease)) {=C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 throw new AlreadyBeingCreatedException(=C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 "failed to create file " + src + " for " + hold=
er +=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 " for client " + clientMachin=
e +=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 " because current leaseholder =
is trying to recreate file.");
It prevents leaseholder to recover the lease if the lease already belongs t=
o him.
This method is called both in append() and create() methods of=C2=A0org.apa=
che.hadoop.hdfs.server.namenode.NameNodeRpcServer
It seems to me that current leaseholder should be able to append the file n=
ormally. Am I wrong?
Hadoop version: 2.5.1
--Best regards, Dmitrii Simonov.

   
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:He=
lveticaNeue-Light, Helvetica Neue Light, Helvetica Neue, Helvetica, Arial, =
Lucida Grande, sans-serif;font-size:16px"><div id=3D"yui_3_16_0_1_142479959=
7491_19659">Hi Dmitry!</div><div id=3D"yui_3_16_0_1_1424799597491_19660"><b=
r></div><div id=3D"yui_3_16_0_1_1424799597491_19661" dir=3D"ltr">I suspect =
its because we don't want two streams from the same DFSClient to write to t=
he same file. The Lease.holder is a simple string which corresponds usually=
 to DFSClient_&lt;someid&gt; .</div><div dir=3D"ltr"><br></div><div id=3D"y=
ui_3_16_0_1_1424799597491_19663" dir=3D"ltr"><span>HTH<br>Ravi.</span></div=
> <div class=3D"qtdSeparateBR"><br><br></div><div style=3D"display: block;"=
 class=3D"yahoo_quoted"> <div style=3D"font-family: HelveticaNeue-Light, He=
lvetica Neue Light, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-s=
erif; font-size: 16px;"> <div style=3D"font-family: HelveticaNeue, Helvetic=
a Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <di=
v dir=3D"ltr"> <font face=3D"Arial" size=3D"2"> On Tuesday, February 24, 20=
15 12:12 AM, Dmitry Simonov &lt;dimmoborgir@gmail.com&gt; wrote:<br> </font=
> </div>  <br><br> <div class=3D"y_msg_container"><div id=3D"yiv1493414219"=
><div dir=3D"ltr">Hello!<div><br></div><div>Could you please explain, why t=
his check exists in class "org.apache.hadoop.hdfs.server.namenode.FSNamesys=
tem", method "recoverLeaseInternal":<br></div><div><br></div><div><div>Leas=
e leaseFile =3D leaseManager.getLeaseByPath(src);</div><div>&nbsp; &nbsp; &=
nbsp; &nbsp; if (leaseFile !=3D null &amp;&amp; leaseFile.equals(lease)) {<=
/div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; throw new AlreadyBeingCreatedE=
xception(</div><div>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; "failed to cr=
eate file " + src + " for " + holder +</div><div>&nbsp; &nbsp; &nbsp; &nbsp=
; &nbsp; &nbsp; " for client " + clientMachine +</div><div>&nbsp; &nbsp; &n=
bsp; &nbsp; &nbsp; &nbsp; " because current leaseholder is trying to recrea=
te file.");</div></div><div><div><br></div><div>It prevents leaseholder to =
recover the lease if the lease already belongs to him.</div><div><br></div>=
<div>This method is called both in append() and create() methods of&nbsp;or=
g.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer</div><div><br></div>=
<div>It seems to me that current leaseholder should be able to append the f=
ile normally. Am I wrong?</div><div><br></div><div>Hadoop version: 2.5.1</d=
iv><br><div class=3D"yiv1493414219gmail_signature">--<div>Best regards, Dmi=
trii Simonov.</div></div>
</div></div></div><br><br></div>  </div> </div>  </div> </div></body></html=
>
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