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ASF GitHub Bot commented on ACCUMULO-1755: ------------------------------------------ Github user keith-turner commented on the pull request: https://github.com/apache/accumulo/pull/75#issuecomment-189540148 > Leaving at 10 (or some other number) provides back pressure to the client threads adding mutations. I beilieve doing this makes it harder to understand the batch writer from a user perspective. This batch writer already provides back pressure based on memory usage. This constraint would provide back pressure in another way that I would not want to attempt to write up in user facing javadocs. > BatchWriter blocks all addMutation calls while binning mutations > ---------------------------------------------------------------- > > Key: ACCUMULO-1755 > URL: https://issues.apache.org/jira/browse/ACCUMULO-1755 > Project: Accumulo > Issue Type: Improvement > Components: client > Reporter: Adam Fuchs > Assignee: Dave Marion > Fix For: 1.8.0 > > Time Spent: 40m > Remaining Estimate: 0h > > Through code inspection, we found that the BatchWriter bins mutations inside > of a synchronized block that covers calls to addMutation. Binning potentially > involves lookups of tablet metadata and processes a fair amount of > information. We will get better parallelism if we can either unlock the lock > while binning, dedicate another thread to do the binning, or use one of the > send threads to do the binning. > This has not been verified empirically yet, so there is not yet any profiling > info to indicate the level of improvement that we should expect. Profiling > and repeatable demonstration of this performance bottleneck should be the > first step on this ticket. -- This message was sent by Atlassian JIRA (v6.3.4#6332)