yahoNanJing opened a new pull request #1810:
URL: https://github.com/apache/arrow-datafusion/pull/1810
# Which issue does this PR close?
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Closes #1703.
# Rationale for this change
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See the detailed discussion in #1703.
# What changes are included in this PR?
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Classify the states in the SchedulerState into two categories:
*VolatileSchedulerState* and *StableSchedulerState*.
According to #1703, the *VolatileSchedulerState* maintains the following
states in memory:
- executor heartbeat
- executor data, mainly for available resources
- tasks
And *StableSchedulerState* maintains the following states in both memory and
storage db:
- executor metadata, mainly for the cluster topology info
- jobs
- stages
The stable states will be stored in both memory and storage db. The
in-memory ones are the cache for fast reading and reducing deserialization cost.
The previous *Watch* in *ConfigBackendClient* for task status is no longer
used. Instead, we leverage an event channel to achieve the job status update.
Later with more states info, like pending tasks, the job status update can be
handled explicitly so that the current cumbersome update implementation will no
longer be used.
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