Please see Threads section at
http://apex.apache.org/docs/apex/development_best_practices/
Note that an operator has only one thread created by the Apex that it
can use to interact with the system. Starting with 3.5.0 release, this
is enforced by the platform and it will throw an exception if an
operator tries to emit on a different thread.
Thank you,
Vlad
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On 2/21/17 11:54, Munagala Ramanath wrote:
To amplify Sandesh's answer a bit, the main operator thread invokes
user callbacks like beginWindow(), endWindow(), process() method of
input ports, and emitTuples() in input operators.
Additionally, if the operator implements the IdleTimeHandler, and if
the operator is deemed to be idle, the handleIdleTime() callback will
be called. All tuple output must be done in one of these callbacks.
So you can check the thread-safe queue in any of these callbacks and
emit output tuples as needed.
Ram
On Tue, Feb 21, 2017 at 11:42 AM, Sandesh Hegde
<sand...@datatorrent.com <mailto:sand...@datatorrent.com>> wrote:
-Removed dev@
Operators can implement idle Time Handler.
https://www.datatorrent.com/docs/apidocs/com/datatorrent/api/Operator.IdleTimeHandler.html
<https://www.datatorrent.com/docs/apidocs/com/datatorrent/api/Operator.IdleTimeHandler.html>
On Tue, Feb 21, 2017 at 11:33 AM Sunil Parmar
<spar...@threatmetrix.com <mailto:spar...@threatmetrix.com>> wrote:
Ram,
Thanks for the prompt response. If we use the approach you
suggested we’re dependent on main thread’s process call I.e.
Tuples in the thread safe queue gets only processed when main
thread is processing incoming tuples. How can we explicitly
call the process from polling of delay queue ?
Just for reference here’s the sample code snippet for our
operator.
public class MyOperator extends BaseOperator implements
Operator.ActivationListener<Context.OperatorContext> {
…..
@InputPortFieldAnnotation
public transient DefaultInputPort<String> kafkaStreamInput =
new DefaultInputPort<String>() {
List<String> errors = new ArrayList<String>();
@Override
public void process(String consumerRecord) {
//Code for normal tuple process
//Code to poll thread safe queue
}
*————————————**—————————————————————————*
*From: *Munagala Ramanath <r...@datatorrent.com
<mailto:r...@datatorrent.com>>
*To: *users@apex.apache.org <mailto:users@apex.apache.org>
*CC: *"d...@apex.apache.org <mailto:d...@apex.apache.org>"
<d...@apex.apache.org <mailto:d...@apex.apache.org>>, Allan De
Leon <adel...@threatmetrix.com
<mailto:adel...@threatmetrix.com>>, Tim Zhu
<t...@threatmetrix.com <mailto:t...@threatmetrix.com>>
*Subject: *Re: Occasional Out of order tuples when emitting
from a thread
*Date: *2017-02-21 10:08 (-0800)
*List: *users@apex.apache.org
<https://lists.apache.org/list.html?users@apex.apache.org>
Please note that tuples should not be emitted by any thread other than
the
main operator thread.
A common pattern is to use a thread-safe queue and have worker threads
enqueue
tuples there; the main operator thread then pulls tuples from the queue
and
emits them.
Ram
_______________________________________________________
Munagala V. Ramanath
Software Engineer
E:r...@datatorrent.com <mailto:r...@datatorrent.com> | M:(408) 331-5034
<tel:%28408%29%20331-5034> | Twitter: @UnknownRam
www.datatorrent.com <http://www.datatorrent.com> |apex.apache.org <http://apex.apache.org>
From: Sunil Parmar <spar...@threatmetrix.com
<mailto:spar...@threatmetrix.com>> Date: Tuesday, February 21,
2017 at 10:05 AM To: "users@apex.apache.org
<mailto:users@apex.apache.org>" <users@apex.apache.org
<mailto:users@apex.apache.org>>, "d...@apex.apache.org
<mailto:d...@apex.apache.org>" <d...@apex.apache.org
<mailto:d...@apex.apache.org>> Cc: Allan De Leon
<adel...@threatmetrix.com <mailto:adel...@threatmetrix.com>>,
Tim Zhu <t...@threatmetrix.com <mailto:t...@threatmetrix.com>>
Subject: Occasional Out of order tuples when emitting from a
thread
Hi there,
We have the following setup:
* we have a generic operator that’s processing tuples in its
input port
* in the input port’s process method, we check for a
condition, and:
o if the condition is met, the tuple is emitted to the
next operator right away (in the process method)
o Otherwise, if the condition is not met, we store the
tuple in some cache and we use some threads that
periodically check the condition to become true. Once
the condition is true, the threads call the emit
method on the stored tuples.
With this setup, we occasionally encounter the following error:
2017-02-15 17:29:09,364 ERROR
com.datatorrent.stram.engine.GenericNode: Catastrophic Error:
Out of sequence BEGIN_WINDOW tuple 58a4046100003b7f on port
transformedJSON while expecting 58a4046100003b7e
Is there a way to make the above work correctly?
If not, can you recommend a better way of doing this?
How can we ensure window assignment is done synchronously
before emitting tuples ?
Thanks very much in advance…
-allan
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_______________________________________________________
Munagala V. Ramanath
Software Engineer
E: r...@datatorrent.com <mailto:r...@datatorrent.com> | M: (408)
331-5034 | Twitter: @UnknownRam
www.datatorrent.com <http://www.datatorrent.com> | apex.apache.org
<http://apex.apache.org>
