Are there any updates on this? From: Wang, Larry Sent: Wednesday, September 27, 2017 5:43 PM To: 'Gerard Toonstra' <[email protected]> Cc: '[email protected]' <[email protected]>; Wang, Ming <[email protected]>; Ren, Xiaoyu <[email protected]> Subject: RE: Qs on airflow
Hi All, Can we stop/start individual running/completed tasks in a DAG? Thanks and best regards Larry Wang From: Gerard Toonstra [mailto:[email protected]] Sent: Monday, September 25, 2017 11:56 PM To: Wang, Larry <[email protected]<mailto:[email protected]>> Cc: [email protected]<mailto:[email protected]>; Wang, Ming <[email protected]<mailto:[email protected]>>; Ren, Xiaoyu <[email protected]<mailto:[email protected]>> Subject: Re: Qs on airflow Hi Larry, 1st: Unfortunately, this is a bit of an issue. You should think of an execution interval (dagrun) of airflow as a piece of work that should complete for that window. Most of your questions try to bypass this design issue and you start to mix different interval settings in the same dagrun. I'm starting to think you're going to set yourself up for a lot of complication that way. The best thing to do is to try to come up with a sensible diagram that you'd expect to run within a single window and then use retries and retry_intervals in a sensible way. If it creates more problems to have one single interval "window" definition (1 week), then you could look into the "TriggerDagRunOperator", which can also help to solve "2". You'd split up the DAG into separate dags, which get run by your controller dags. Then it should become easier to control how/when each task gets run and for which kind of interval. Yes, the sensor will continue to execute and it will duplicate itself for each dagrun. The LatestOnlyOperator wouldn't be helpful there, because it would already have passed it. I'm not sure if anything changed in the sensor logic since I last checked, but these things continue to run on a worker with a configured interval. An alternative would be to create your own operator that 'fails' instead (and doesn't keep running) and then gets retried until it either starves the retry-count or succeeds. That way it doesn't consume workers. 2nd: Not aware of any filters for this, but see 1. Split it out to a different DAG altogether perhaps. I never used subdags and heard some scary stories about those. 3rd: Did you see the "landing times" UI screen available from the top menu? You can also look into the airflow database and run your own queries there. Some crude charting can be customized with a bit of python and queries on that database together with the "graphviz" tool, specifically dot. It's a very simple ASCII file that you generate and then convert using "dot -Tpng -osomefile.png <mydotfile.dot>" It's got a rich syntax for adding text to edges, etc. If you want to do critical path analysis, gantt charts could be helpful. You can look into plotly for that: https://plot.ly/python/gantt/ Rgds, Gerard On Mon, Sep 25, 2017 at 11:50 AM, Wang, Larry <[email protected]<mailto:[email protected]>> wrote: Dear experts, We figured out how to do this by using sensor and ShortCircuitOperator, attached the code for detail information, here we met several issues as in below. 1st , it seems m_sensor also involves in the scheduling and running out of the task instances, how should we avoid that? Can we just make it happen only once. [cid:[email protected]] 2nd, How can we hide out the ones w/o prefix of bbt in the tree? Are there any filter for this? 3rd, We are seeking a way to get the execution summary of each time instead of the tree view and draw it in a chart, are there any way to do this? E.g. bbt_low_loginvsi run once and consume 18 hours. Bbt_opt_1 run 8 times and consume 70 hours in total Thanks and best regards Larry Wang From: Wang, Larry Sent: Monday, September 25, 2017 2:40 PM To: 'Gerard Toonstra' <[email protected]<mailto:[email protected]>>; '[email protected]<mailto:[email protected]>' <[email protected]<mailto:[email protected]>>; Wang, Ming <[email protected]<mailto:[email protected]>>; Ren, Xiaoyu <[email protected]<mailto:[email protected]>> Subject: RE: Qs on airflow Thanks so much for your valuable comments. We are using Jenkins operator to orchestrate the Jenkins build from airflow. The thing is that our base line workloads start in 3 phases to build our Jenkins jobs and never stop, for example, phase 1 workload starts in day 1 while phase 2 workload starts in day 3 without the stopping of the day 1 workload (and the they must be running at same time after day 3), we will use Xcom and sensor like you mentioned to see if it works. Some other questions are also listed in below, please check. 1st, Can we set different scheduler for DAGs and its sub DAGs, e.g. DAGs are triggered weekly, but sub DAGs are triggered hourly? 2nd, Is there any way to export the Graph view/Tree view from the airflow UI? 3rd, How can we add delay between tasks in one DAG besides sensor? Thanks and best regards Larry Wang From: Wang, Larry Sent: Monday, September 25, 2017 2:23 PM To: 'Gerard Toonstra' <[email protected]<mailto:[email protected]>>; '[email protected]<mailto:[email protected]>' <[email protected]<mailto:[email protected]>>; Wang, Ming <[email protected]<mailto:[email protected]>>; Ren, Xiaoyu <[email protected]<mailto:[email protected]>> Subject: RE: Qs on airflow From: Gerard Toonstra [mailto:[email protected]] Sent: Monday, September 25, 2017 2:01 PM To: [email protected]<mailto:[email protected]>; Wang, Larry <[email protected]<mailto:[email protected]>> Subject: Re: Qs on airflow Hi Larry, The important thing to question is what kind of interface that other system has. It is a little bit unusual in the sense that this DAG processes across multiple days. The potential issue I foresee here is that you don't mention a consistent start date for the DAG and you expect this to run in an ad-hoc manner. Most DAGs would process "windows" of activity and you may get some issues with the time always resetting to the defined scheduled start of the DAG. What most DAGs would do to enable this is to have sensor tasks in the DAG. A Hadoop job for example executes asynchronously from the originating request. You'd have a task to kick off the job, save the job id and then in another task fetch the job id through xcom and continue polling using this sensor task to verify if the job finished (with either failed or finished). Then you allow the DAG to continue or fail. So this is where the job interface question comes into play. It depends what you have available to verify the status of jobs and then you'd probably write some operators around that job interface. If these jobs never surpass a week, then you could start defining a week interval, so you're never crossing these boundaries. Then look into for example the LatestOnlyOperator on how you can get the left-most execution date (datetime) when the dagrun was started. There should be other ways to get the exact start/datetime of the task of your interest (when the job was started), then figure out the total processing time you need. Then run that sensor every hour in a retry or something. Alternatives are to look at what these tasks produce. For example, if you drop files into S3 at the end of a process, look for those artifacts as a means to identify if the task succeeded or failed. Or perhaps even easier, write control files in each workload that you can check for in airflow, which can be easier than having to implement a job control interface thingy. You could also start the DAG and rely on 'retry' functionality in airflow and then you calculate what interval size and how many retries you need to get to 3 days in total, after which that task fails. Rgds, Gerard On Mon, Sep 25, 2017 at 3:41 AM, Wang, Larry <[email protected]<mailto:[email protected]>> wrote: Any updates on this? we basically want to build following DAG, and the group of BBTs in rectangle( start with snap should be triggered in daily basis) From: Wang, Larry Sent: Sunday, September 24, 2017 11:23 PM To: '[email protected]<mailto:[email protected]>' <[email protected]<mailto:[email protected]>> Subject: Qs on airflow Hi experts, I am new to airflow and want to ask some questions of it to see if it is possible to leverage this tool in our daily works, please check them in below. 1st, I am implementing a system with 3 level workloads, the 1st workloads is triggered at day 1, and then the 2nd workload is triggered at day 3 only if the 1st job could run long enough with 3 days and then the last workload will be trigger at day 5 if both previous workloads could continue running. Is this possible mapping to DAGs of the airflow? 2nd, Given the 1st workloads warming up and keep consuming certain system resources, a bunch operation will be kicked out in a queue, is it possible? Thanks and best regards Larry Wang
