moves hosting request processing from tserver to manager#3437
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keith-turner merged 4 commits intoapache:elasticityfrom May 30, 2023
Merged
moves hosting request processing from tserver to manager#3437keith-turner merged 4 commits intoapache:elasticityfrom
keith-turner merged 4 commits intoapache:elasticityfrom
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Processing of hosting request was moved from the tserver to manager so that the tablet group watcher could be notified. This considerably reduces the delay in getting an ondemand tablet hosted. Introduced a cache to avoid reprocessing hosting request for the same tablet in a short time period. Modified the update of the hosting request column to use a conditional mutation. This avoids a metadata read before write (the read is now done by the mutation conditions) and avoids race conditions. Moving the hosting request to the manager could introduce scaling problems, however the cache can help with this. The reduced latency for hosting ondemand tablet is needed, so if there are scaling problems a soluting will need to be found that has low latency for hosting.
keith-turner
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dlmarion
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May 30, 2023
server/manager/src/main/java/org/apache/accumulo/manager/ManagerClientServiceHandler.java
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Processing of hosting request was moved from the tserver to manager so that the tablet group watcher could be notified. This considerably reduces the delay in getting an ondemand tablet hosted.
Introduced a cache to avoid reprocessing hosting request for the same tablet in a short time period.
Modified the update of the hosting request column to use a conditional mutation. This avoids a metadata read before write (the read is now done by the mutation conditions) and avoids race conditions.
Moving the hosting request to the manager could introduce scaling problems, however the cache can help with this. The reduced latency for hosting ondemand tablet is needed, so if there are scaling problems a solution will need to be found that has low latency for hosting.