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From Keith Turner <ke...@deenlo.com>
Subject Re: cached connector
Date Mon, 29 Feb 2016 15:57:17 GMT
On Mon, Feb 29, 2016 at 10:26 AM, z11373 <z11373@outlook.com> wrote:

> Hi Keith,
> Yes, T=1 was calling createScanner, and yes, my current code does create
> single scanner per thread, but I already have new code does use
> BatchScanner.
>
> For T=4, it's another thread, but I believe it was spawned from thread
> 0x1f46, there are many of this stack, and I just noticed few of them have
> this stack:
>
> "pool-3-thread-1277" #7656 prio=5 os_prio=0 tid=0x00007fee9408e000
> nid=0x2033 waiting for monitor entry [0x00007fef9f0f1000]
>    java.lang.Thread.State: BLOCKED (on object monitor)
>     at
>
> org.apache.accumulo.core.client.impl.TabletLocator.getLocator(TabletLocator.java:101)
>     - waiting to lock <0x000000068032c130> (a java.lang.Class for
> org.apache.accumulo.core.client.impl.TabletLocator)
>     at
>
> org.apache.accumulo.core.client.impl.ThriftScanner.scan(ThriftScanner.java:228)
>     at
>
> org.apache.accumulo.core.client.impl.ScannerIterator$Reader.run(ScannerIterator.java:84)
>     at
>
> org.apache.accumulo.core.client.impl.ScannerIterator.hasNext(ScannerIterator.java:177)
>     ...
>
> That 'BLOCKED' state seems suspicious to me.
>

Its waiting to lock 0x000000068032c130, would be nice to see what thread
has 0x000000068032c130 locked and what that thread is doing.


>
> For T=5, the high level thread was calling scanner iterator's hasNext()
>
> Do you know why reading via this connector would take > 8s, while on new
> connector (in same process), the read would mostly only take < 0.1s (see
> that huge difference)?
>

I don't know.   One guess is that the connector was created w/
older/different config (like list of zookeepers) and something has to
timeout (like a connection to non-existant zookeeper) before it makes
progress.

Note, the tablet locator (cache of tablet locations) is a static resource
shared among all connectors created in same classloader.


>
> Thanks,
> Z
>
>
>
>
> --
> View this message in context:
> http://apache-accumulo.1065345.n5.nabble.com/cached-connector-tp16202p16262.html
> Sent from the Developers mailing list archive at Nabble.com.
>

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