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fanrui commented on FLINK-26762: -------------------------------- Thanks for your quick feedback. By default, the memory-segment size is 32KB, so what's the difference between the overdraft-memory-size and overdraft-buffers? Please give some details, thanks. Do you mean that some exclusive/floating buffers should also be counted in the overdraft-memory? As I understand it, overdraft-memory means: in addition to exclusive/floating, the extra memory that is allowed to be requested. > Add the overdraft buffer in BufferPool to reduce unaligned checkpoint being > blocked > ----------------------------------------------------------------------------------- > > Key: FLINK-26762 > URL: https://issues.apache.org/jira/browse/FLINK-26762 > Project: Flink > Issue Type: Improvement > Components: Runtime / Checkpointing, Runtime / Network > Affects Versions: 1.13.0, 1.14.0, 1.15.0 > Reporter: fanrui > Assignee: fanrui > Priority: Major > Fix For: 1.16.0 > > > In some past JIRAs of Unaligned Checkpoint, the community has added the > recordWriter.isAvaliable() to reduce block for single record write. But for > large record, flatmap or broadcast watermark, they may need more buffer. > Can we add the overdraft buffer in BufferPool to reduce unaligned checkpoint > being blocked? > h2. Overdraft Buffer mechanism > Add the configuration of > 'taskmanager.network.memory.overdraft-buffers-per-gate=5'. > When requestMemory is called and the bufferPool is insufficient, the > bufferPool will allow the Task to overdraw up to 5 MemorySegments. And > bufferPool will be unavailable until all overdrawn buffers are consumed by > downstream tasks. Then the task will wait for bufferPool being available. > From the above, we have the following benefits: > * For scenarios that require multiple buffers, the Task releases the > Checkpoint lock, so the Unaligned Checkpoint can be completed quickly. > * We can control the memory usage to prevent memory leak. > * It just needs a litter memory, and can improve the stability of the Task > under back pressure. > * Users can increase the overdraft-buffers to adapt the scenarios that > require more buffers. > > Masters, please correct me if I'm wrong, thanks a lot. -- This message was sent by Atlassian Jira (v8.20.1#820001)