Sean was right a while back about threads popping up in a Spoon-Carte
It was caused by a weirdness in the Apache Commons HTTP client library that
didn't release a connection upon calling ... releaseConnection().

The reason was hard to find but apparently if you create a new HTTPClient()
object it also creates a simple connection pool of one connection. Since
it's a pool of one it keeps the connection open. Since new pools and new
connections are created all the time & the connections are never ever
released. Nifty!

I'm copying the rest of the devs in case anyone else (like me) was too lazy
to use a MultiThreadedHttpConnectionManager to create an HTTPClient.

The problem's been fixed in PDI 4.2.0 a while back (with the
SlaveConnectionManager singleton) but I'd thought I'd mention it anyway in
case anyone else is using that library. Sneaky things these loose threads,
they are.


2011/4/22 Sean J. Flatley <sflatley (AT) pentaho (DOT) com>

> I have a simple transformation, text file input hopped to a text file
> output. The text file output is running on a cluster.
> The transformation is attached.
> Running the transformation in debug mode shows that text file input
> reads all rows from the customer-100 sample file. The text output step
> gets the first row from the text input step and hangs there.
> I set up the carte servers for remote debugging and tracked down where
> the log statement is written, in the RemoteStep class at line 493. I
> stepped though the debugger to the baseStep.putRowto method.
> Here is where things get weird.
> At line 1299 is a synchronized (this) block. Stepping through the code
> stops here. *Every 10 seconds or so a new thread pops up.*
> Have you seen this before?

Matt Casters <mcasters (AT) pentaho (DOT) org>
Chief Data Integration, Kettle founder, Author of Pentaho Kettle
(Wiley <>)
Fonteinstraat 70, 9400 OKEGEM - Belgium - Cell : +32 486 97 29 37
Pentaho : The Commercial Open Source Alternative for Business Intelligence

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