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catalyst / moodle-tool_lockstats

Moodle cron / task API lock statistics admin tool
https://moodle.org/plugins/tool_lockstats
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Handle high-concurrecny adhoc tasks better #87

Closed andrewnicols closed 4 years ago

andrewnicols commented 4 years ago

When running high numbers of adhoc tasks on a fast system with multiple cron runners and after the implementation of MDL-67596, it's quite possible for a task to be looked at by multiple runners because the task still exists in the database at the time that the runner starts to request a new task.

This is harmless enough because they fail to acquire a lock and continue to look at the next task.

However, when a task finishes running it removes the record. When the runner fetches a list on a busy system, it may encounter a number of tasks which are still in-progress, and then get to a shorter-lived task which is no longer in progress and has now been removed from the database.

However the lockstats plugin makes the assumption that the adhoc task record still exists.

brendanheywood commented 4 years ago

Doh! This looked very familiar - I actually found these same issues testing last week, and while reviewing this I realized my near identical fixes are still sitting there uncommited on my dev box :/

brendanheywood commented 4 years ago

thanks @andrewnicols this is all sorted now