Zheng Hu created HDFS-14541: ------------------------------- Summary: ShortCircuitReplica#unref cost about 6% cpu and 6% heap allocation because of the frequent thrown NoSuchElementException in our HBase benchmark Key: HDFS-14541 URL: https://issues.apache.org/jira/browse/HDFS-14541 Project: Hadoop HDFS Issue Type: Bug Reporter: Zheng Hu Attachments: async-prof-pid-94152-alloc-2.svg, async-prof-pid-94152-cpu-1.svg
Our XiaoMi HBase team are evaluating the performence improvement of HBASE-21879, and we have few CPU flame graph & heap flame graph by using async-profiler, and found that there're some performence issues in DFSClient now . See the attached two flame graph, we can conclude that the try catch block in ShortCircuitCache#trimEvictionMaps has some serious perf problem now, we should remove this from DFSClient. {code} /** * Trim the eviction lists. */ private void trimEvictionMaps() { long now = Time.monotonicNow(); demoteOldEvictableMmaped(now); while (true) { long evictableSize = evictable.size(); long evictableMmappedSize = evictableMmapped.size(); if (evictableSize + evictableMmappedSize <= maxTotalSize) { return; } ShortCircuitReplica replica; try { if (evictableSize == 0) { replica = (ShortCircuitReplica)evictableMmapped.get(evictableMmapped .firstKey()); } else { replica = (ShortCircuitReplica)evictable.get(evictable.firstKey()); } } catch (NoSuchElementException e) { break; } if (LOG.isTraceEnabled()) { LOG.trace(this + ": trimEvictionMaps is purging " + replica + StringUtils.getStackTrace(Thread.currentThread())); } purge(replica); } } {code} -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org