I definitely keep running into use cases where it would be nice if there was a proper way in NiFi to say “Hey Process Group, your only allowed to process one input file at a time and can’t do anything else until it’s done”
Can you share an example of your workflow. I’ll take a look and see if it’s one of the more common gotchas for wait/notify. Thanks From: David Gallagher <dgallag...@cleverdevices.com> Reply-To: "users@nifi.apache.org" <users@nifi.apache.org> Date: Wednesday, June 12, 2019 at 11:16 AM To: "users@nifi.apache.org" <users@nifi.apache.org> Subject: RE: Wait processor decrements count below zero Hi Shawn – thanks for the insight! There are Notify processors in several places within the flow that set the Signal Counter Delta to 1, but any one flowfile would never trip more than one of them. There’s also a generator Notify that initializes the gate to 1. Immediately after the Wait processor, there’s a Notify that sets the Signal Counter Delta to 0 to prevent the next flowfile from proceeding before the gate is cleared. If there is work waiting in the Wait queue, that could be tripping the back-to-back issue… Thanks, Dave From: Shawn Weeks <swe...@weeksconsulting.us> Sent: Wednesday, June 12, 2019 11:50 AM To: users@nifi.apache.org Subject: Re: Wait processor decrements count below zero How are you setting the value to “1” in the Notify Processor? Do you have two Notify’s back to back with one setting to 0 and then the next incrementing by one. I’ve always had trouble if several Notify’s are trying to change the same key because the Wait sees the value as it flip/flops. Thanks Shawn From: David Gallagher <dgallag...@cleverdevices.com<mailto:dgallag...@cleverdevices.com>> Reply-To: "users@nifi.apache.org<mailto:users@nifi.apache.org>" <users@nifi.apache.org<mailto:users@nifi.apache.org>> Date: Wednesday, June 12, 2019 at 10:44 AM To: "users@nifi.apache.org<mailto:users@nifi.apache.org>" <users@nifi.apache.org<mailto:users@nifi.apache.org>> Subject: Wait processor decrements count below zero Hi – I have a gate set up with a Wait processor listening for a target signal count of ‘1’. I have several Notify processors that set the value to ‘1’ when the system is able to take work. If there is work waiting in the queue while the ‘gate’ is closed, I sometimes get this error: Wait[id=016b1003-bf40-1031-d67b-3fa2c1f1acc9] Wait[id=016b1003-bf40-1031-d67b-3fa2c1f1acc9] failed to process session due to fromIndex(0) > toIndex(-1); Processor Administratively Yielded for 1 sec: java.lang.IllegalArgumentException: fromIndex(0) > toIndex(-1) Is this because of something that I’m configuring incorrectly on the Wait processor? When the gate is set to 1 by a Notify processor, it seems as though the work will not get released from the Wait queue until the number for the signal is greater than or equal to the ‘toIndex’ indicated in the message. Thanks, Dave
