Details
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Improvement
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Status: Closed
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Critical
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Resolution: Fixed
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None
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None
Description
Currently, the number of network buffer per task manager is preconfigured and the memory is pre-allocated through taskmanager.network.numberOfBuffers config. In a Job DAG with shuffle phase, this number can go up very high depends on the TM cluster size. The formula for calculating the buffer count is documented here (https://ci.apache.org/projects/flink/flink-docs-master/setup/config.html#configuring-the-network-buffers).
#slots-per-TM^2 * #TMs * 4
In a standalone deployment, we may need to control the task manager cluster size dynamically and then leverage the up-coming Flink feature to support scaling job parallelism/rescaling at runtime.
If the buffer count config is static at runtime and cannot be changed without restarting task manager process, this may add latency and complexity for scaling process. I am wondering if there is already any discussion around whether the network buffer should be automatically managed by Flink or at least expose some API to allow it to be reconfigured. Let me know if there is any existing JIRA that I should follow.
