死锁时更新`djcelery_periodictask`表

Question

我有一个两个简单的周期性芹菜任务，运行在晚上，一个在凌晨2点，其他在凌晨3点，并从时间以下抛出异常关于djcelery_periodictask表的死锁，我不太明白。看来，一个任务试图，而其他则仍持有其共享锁更新djcelery_periodictask：

deadlock detected Detail: Process 32353 waits for ShareLock on transaction 39280165; blocked by process 32306. Process 32306 waits for ShareLock on transaction 39280166; blocked by process 32353. 
Process 32353: 
UPDATE "djcelery_periodictask" SET "name" = 'app.tasks.task1', "task" = 'app.tasks.task1', "interval_id" = NULL, "crontab_id" = 4, "args" = '[]', "kwargs" = '{}', "queue" = NULL, "exchange" = NULL, "routing_key" = NULL, "expires" = NULL, "enabled" = true, "last_run_at" = '2015-02-10 03:00:00.001297+01:00', "total_run_count" = 117, "date_changed" = '2015-02-10 02:00:00.010033+00:00', "description" = '' WHERE "djcelery_periodictask"."id" = 4 
Process 32306: 
UPDATE "djcelery_periodictask" SET "name" = 'app.tasks.task2', "task" = 'app.tasks.task2', "interval_id" = NULL, "crontab_id" = 6, "args" = '[]', "kwargs" = '{}', "queue" = NULL, "exchange" = NULL, "routing_key" = NULL, "expires" = NULL, "enabled" = true, "last_run_at" = '2015-02-10 02:00:00.014189+01:00', "total_run_count" = 63, "date_changed" = '2015-02-10 02:00:00.015097+00:00', "description" = '' WHERE "djcelery_periodictask"."id" = 6 
Hint: See server log for query details. Query: 
UPDATE "djcelery_periodictask" SET "name" = 'app.tasks.task2', "task" = 'appt.tasks.task2', "interval_id" = NULL, "crontab_id" = 4, "args" = '[]', "kwargs" = '{}', "queue" = NULL, "exchange" = NULL, "routing_key" = NULL, "expires" = NULL, "enabled" = true, "last_run_at" 

怎么能有两个上仅包含几个行陷入僵局表一个简单的更新？

Answer 1

我的问题是，我有我所有的工人开始-B参数，打开每一个工人在一个周期性的任务调度：

-B, --beat   Also run the celery beat periodic task scheduler. 
         Please note that there must only be one instance of 
         this service. 

其结果是，该计划的任务被多次启动，都在同时，尝试更新djcelery_periodictask表时创建死锁。