scheduler | 易学教程

How to stop a task in ScheduledThreadPoolExecutor once I think it's completed

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问题 I have a ScheduledThreadPoolExecutor with which I schedule a task to run at a fixed rate. I want the task to be running with a specified delay for a maximum of say 10 times until it "succeeds". After that, I will not want the task to be retried. So basically I'll need to stop running the scheduled task when I want it to be stopped, but without shutting down the ScheduledThreadPoolExecutor. Any idea how I'd do that? Here's some pseudocode - public class ScheduledThreadPoolExecutorTest { public

Calculate next scheduled time based on cron spec

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问题 What's an efficient way to calculate the next run time of an event given the current time and a cron spec? I'm looking for something other than "loop through every minute checking if it matches spec". Examples of specs might be: Every month, on the 1st and 15 at 15:01 At 10,20,30,40,50 mins past the hour every hour Python code would be lovely but psuedo code or high level description would also be appreciated. [Update] Assume the spec is already parsed and is in some reasonable format. 回答1:

Airflow: pass {{ ds }} as param to PostgresOperator

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i would like to use execution date as parameter to my sql file: i tried dt = '{{ ds }}' s3_to_redshift = PostgresOperator( task_id='s3_to_redshift', postgres_conn_id='redshift', sql='s3_to_redshift.sql', params={'file': dt}, dag=dag ) but it doesn't work. dt = '{{ ds }}' Doesn't work because Jinja (the templating engine used within airflow) does not process the entire Dag definition file. For each Operator there are fields which Jinja will process, which are part of the definition of the operator itself. In this case, you can make the params field (which is actually called parameters , make

Running batch files sequentially in win 7 task scheduler

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I have 2 batch files as "actions" in a single task. The first one does a scan for viruses using microsoft security essentials. The second one puts the computer to sleep. The problem is that when the task is run, it seems like both batch files run simultaneously, that is, I can see the start of the virus scan, but then the computer goes to sleep almost immediately, so the scan really never has a chance to start. I understood that batch files would run in sequential order in the task scheduler. Am I wrong? How do I make the sleep batch file wait until the scan batch file has completed? Here are

How SMP schedule work in Linux kernel? (ARM architecture)

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问题 In linux, the scheduler will be triggered when a specific amount of time has passed. As I understood, the timer triggers an interrupt which in turn triggers a call to schedule . In a SMP system, I read in the book "Understanding the Linux Kernel" that "each processor runs the scheduler() function on its own". Does this mean every timer interrupt triggers every cpus to do a re-schedule at the same time? 回答1: The ARM SMP systems support two types of interrupts. SPI (shared peripheral interrupt)

What is the difference between the fair and capacity schedulers?

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问题 I am new to the world of Hadoop and want to know the difference between fair and capacity schedulers. Also when are we supposed to use each one? Please answer in a simple way because I read many things on the Internet but I don't get much from them. 回答1: Fair scheduling is a method of assigning resources to jobs such that all jobs get, on average, an equal share of resources over time. When there is a single job running, that job uses the entire cluster. When other jobs are submitted, tasks

Linux perf events: cpu-clock and task-clock - what is the difference

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问题 Linux perf tools (some time ago named perf_events ) has several builtin universal software events. Two most basic of them are: task-clock and cpu_clock (internally called PERF_COUNT_SW_CPU_CLOCK and PERF_COUNT_SW_TASK_CLOCK ). But what is wrong with them is lack of description. ysdx user reports that man perf_event_open has short description: PERF_COUNT_SW_CPU_CLOCK This reports the CPU clock, a high-resolution per- CPU timer. PERF_COUNT_SW_TASK_CLOCK This reports a clock count specific to

java quartz scheduler fire a new job immediately

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问题 Is it possible to crate a job that will trigger immediately ? when i want the job to be triggres now i builed a cron expression string with the current date and time - i think it's too complicated, is there another way to trigger the job immediately ? Thank's In Advance. 回答1: All the Jobs registered in the Quartz Scheduler are uniquely identified by the JobKey which is composed of a name and group . You can fire the job which has a given JobKey immediately by calling triggerJob(JobKey jobKey)

Is it possible for Airflow scheduler to first finish the previous day's cycle before starting the next?

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Right now, nodes in my DAG proceeds to the next day's task before the rest of the nodes of that DAG finishes. Is there a way for it to wait for the rest of the DAG to finish before moving unto the next day's DAG cycle? (I do have depends_on_past as true, but that does not work in this case) My DAG looks like this: O l V O -> O -> O -> O -> O Also, tree view pic of the dag] Oleg Yamin Might be a bit late for this answer, but I ran into the same issue and the way I resolved it is I added two extra tasks in each dag. "Previous" at the start and "Complete" at the end. Previous task is external

How does cron internally schedule jobs?

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问题 How do "modern" cron daemons internally schedule their jobs? Some crond s used to schedule a run every so often via at . So after a crontab is written out, does crond : Parse the crontab for all future events and the sleep for the intervals? Poll an aggregated crontab database every minute to determine if the current time matches the schedule pattern? Other? Thanks, 回答1: A few crickets heard in this question. Good 'ol RTFC with some discrete event simulation papers and Wikipedia: http://en