Hello All,

If our read of https://issues.apache.org/jira/browse/HBASE-5898 is correct
it talks about three issues:

#1 Contention on a lock causing bad performance
#2 HDFS slowness causing IPC handlers blocked for large times.
#3 A mysterious bug which causes what looks like a deadlock

In out environment[1] we are seeing #3 (ish) signals. Attached is the stack
trace. One of our region server got blocked (almost all of IPC handlers)
for 11 hours, so it can not be #1 OR #2.

We have not back ported the patch yet so cant say if it fixes the issue or
not. Also it is difficult to reproduce.  There is a rumor that a program to
reproduce this issue exist, does it?

Eager to hear thoughts.

[1] HBase version 0.92.2 , Hadoop version CDH3u0
-Shrijeet

Shrijeet:
The attachment didn't go through.

Can you use pastebin ?

Thanks

On Tue, Dec 11, 2012 at 12:05 PM, Shrijeet Paliwal
<[EMAIL PROTECTED]>wrote:

> Hello All,
>
> If our read of https://issues.apache.org/jira/browse/HBASE-5898 is
> correct it talks about three issues:
>
> #1 Contention on a lock causing bad performance
> #2 HDFS slowness causing IPC handlers blocked for large times.
> #3 A mysterious bug which causes what looks like a deadlock
>
> In out environment[1] we are seeing #3 (ish) signals. Attached is the
> stack trace. One of our region server got blocked (almost all of IPC
> handlers) for 11 hours, so it can not be #1 OR #2.
>
> We have not back ported the patch yet so cant say if it fixes the issue or
> not. Also it is difficult to reproduce.  There is a rumor that a program to
> reproduce this issue exist, does it?
>
> Eager to hear thoughts.
>
> [1] HBase version 0.92.2 , Hadoop version CDH3u0
> -Shrijeet
>

Done https://gist.github.com/4261746
On Tue, Dec 11, 2012 at 12:10 PM, Ted Yu <[EMAIL PROTECTED]> wrote:

> Shrijeet:
> The attachment didn't go through.
>
> Can you use pastebin ?
>
> Thanks
>
> On Tue, Dec 11, 2012 at 12:05 PM, Shrijeet Paliwal
> <[EMAIL PROTECTED]>wrote:
>
> > Hello All,
> >
> > If our read of https://issues.apache.org/jira/browse/HBASE-5898 is
> > correct it talks about three issues:
> >
> > #1 Contention on a lock causing bad performance
> > #2 HDFS slowness causing IPC handlers blocked for large times.
> > #3 A mysterious bug which causes what looks like a deadlock
> >
> > In out environment[1] we are seeing #3 (ish) signals. Attached is the
> > stack trace. One of our region server got blocked (almost all of IPC
> > handlers) for 11 hours, so it can not be #1 OR #2.
> >
> > We have not back ported the patch yet so cant say if it fixes the issue
> or
> > not. Also it is difficult to reproduce.  There is a rumor that a program
> to
> > reproduce this issue exist, does it?
> >
> > Eager to hear thoughts.
> >
> > [1] HBase version 0.92.2 , Hadoop version CDH3u0
> > -Shrijeet
> >
>

Have you seen Lars' comment today on the JIRA ?

I don't know whether CDH3u0 is close to hdfs 1.0.3 or 1.0.4

Cheers

On Tue, Dec 11, 2012 at 12:14 PM, Shrijeet Paliwal
<[EMAIL PROTECTED]>wrote:

> Done https://gist.github.com/4261746
>
>
> On Tue, Dec 11, 2012 at 12:10 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
>
> > Shrijeet:
> > The attachment didn't go through.
> >
> > Can you use pastebin ?
> >
> > Thanks
> >
> > On Tue, Dec 11, 2012 at 12:05 PM, Shrijeet Paliwal
> > <[EMAIL PROTECTED]>wrote:
> >
> > > Hello All,
> > >
> > > If our read of https://issues.apache.org/jira/browse/HBASE-5898 is
> > > correct it talks about three issues:
> > >
> > > #1 Contention on a lock causing bad performance
> > > #2 HDFS slowness causing IPC handlers blocked for large times.
> > > #3 A mysterious bug which causes what looks like a deadlock
> > >
> > > In out environment[1] we are seeing #3 (ish) signals. Attached is the
> > > stack trace. One of our region server got blocked (almost all of IPC
> > > handlers) for 11 hours, so it can not be #1 OR #2.
> > >
> > > We have not back ported the patch yet so cant say if it fixes the issue
> > or
> > > not. Also it is difficult to reproduce.  There is a rumor that a
> program
> > to
> > > reproduce this issue exist, does it?
> > >
> > > Eager to hear thoughts.
> > >
> > > [1] HBase version 0.92.2 , Hadoop version CDH3u0
> > > -Shrijeet
> > >
> >
>

On Tue, Dec 11, 2012 at 12:26 PM, Ted Yu <[EMAIL PROTECTED]> wrote:

> I don't know whether CDH3u0 is close to hdfs 1.0.3 or 1.0.4
>

Ted, CDH3u0 does not have HDFS-2246 (Shortcut a local client reads to a
Datanodes files directly) I think it is included in CDH3u3.

We might be facing HBASE-3622 . Recently removed the UseMemBar from our GC
opts. I will bring it back & see if the issue gets resolved.
On Tue, Dec 11, 2012 at 12:50 PM, Shrijeet Paliwal
<[EMAIL PROTECTED]>wrote:

>
>
> On Tue, Dec 11, 2012 at 12:26 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
>
>> I don't know whether CDH3u0 is close to hdfs 1.0.3 or 1.0.4
>>
>
> Ted, CDH3u0 does not have HDFS-2246 (Shortcut a local client reads to a
> Datanodes files directly) I think it is included in CDH3u3.
>

This really looks like the issue we got that prompted applying HBASE-5898.

Never heard about the rumor.

If you can isolate the region that exhibits the issue, put it on a
region server by itself and patch that region server to see if it
fixes the issue.

Also, can you confirm that you are running java 1.6 u16?

Thx,

J-D

On Tue, Dec 11, 2012 at 12:14 PM, Shrijeet Paliwal
<[EMAIL PROTECTED]> wrote:
> Done https://gist.github.com/4261746
>
>
> On Tue, Dec 11, 2012 at 12:10 PM, Ted Yu <[EMAIL PROTECTED]> wrote:
>
>> Shrijeet:
>> The attachment didn't go through.
>>
>> Can you use pastebin ?
>>
>> Thanks
>>
>> On Tue, Dec 11, 2012 at 12:05 PM, Shrijeet Paliwal
>> <[EMAIL PROTECTED]>wrote:
>>
>> > Hello All,
>> >
>> > If our read of https://issues.apache.org/jira/browse/HBASE-5898 is
>> > correct it talks about three issues:
>> >
>> > #1 Contention on a lock causing bad performance
>> > #2 HDFS slowness causing IPC handlers blocked for large times.
>> > #3 A mysterious bug which causes what looks like a deadlock
>> >
>> > In out environment[1] we are seeing #3 (ish) signals. Attached is the
>> > stack trace. One of our region server got blocked (almost all of IPC
>> > handlers) for 11 hours, so it can not be #1 OR #2.
>> >
>> > We have not back ported the patch yet so cant say if it fixes the issue
>> or
>> > not. Also it is difficult to reproduce.  There is a rumor that a program
>> to
>> > reproduce this issue exist, does it?
>> >
>> > Eager to hear thoughts.
>> >
>> > [1] HBase version 0.92.2 , Hadoop version CDH3u0
>> > -Shrijeet
>> >
>>

On Tue, Dec 11, 2012 at 12:32 PM, Jean-Daniel Cryans <[EMAIL PROTECTED]>wrote:

> This really looks like the issue we got that prompted applying HBASE-5898.
>
> Never heard about the rumor.
>

Was referring to Stack's comment http://goo.gl/1dMVb

>
> If you can isolate the region that exhibits the issue, put it on a
> region server by itself and patch that region server to see if it
> fixes the issue.
>

I can isolate the region fine (when we attempted to restart the
regionserver, stuck threads got interrupted & logged the region name they
were trying to load data for). But that region has gone through a minor
compaction and the situation (files et al) in file system has changed. I am
asssuming state of filesystem is what you were hoping will help us
reproduce. Or you are coming from some where else?
> Also, can you confirm that you are running java 1.6 u16?
>

Yes we are running Java 1.6.0_16.