[jira] [Updated] (HIVE-10128) LLAP: BytesBytesMultiHashMap does not allow concurrent read-only access
[ https://issues.apache.org/jira/browse/HIVE-10128?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Sergey Shelukhin updated HIVE-10128: Attachment: HIVE-10128.01.patch Patch for trunk. [~ashutoshc] can you review? thanks LLAP: BytesBytesMultiHashMap does not allow concurrent read-only access --- Key: HIVE-10128 URL: https://issues.apache.org/jira/browse/HIVE-10128 Project: Hive Issue Type: Sub-task Reporter: Gopal V Assignee: Sergey Shelukhin Attachments: HIVE-10128.01.patch, HIVE-10128.patch, hashmap-after.png, hashmap-sync-source.png, hashmap-sync.png The multi-threaded performance takes a serious hit when LLAP shares hashtables between the probe threads running in parallel. !hashmap-sync.png! This is an explicit synchronized block inside ReusableRowContainer which triggers this particular pattern. !hashmap-sync-source.png! Looking deeper into the code, the synchronization seems to be caused due to the fact that WriteBuffers.setReadPoint modifies the otherwise read-only hashtable. To generate this sort of result, run LLAP at a WARN log-level, to avoid all the log synchronization that otherwise affects the thread sync. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
[jira] [Updated] (HIVE-10128) LLAP: BytesBytesMultiHashMap does not allow concurrent read-only access
[ https://issues.apache.org/jira/browse/HIVE-10128?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Gopal V updated HIVE-10128: --- Attachment: hashmap-after.png Fix looks good, the hashmap sync points have gone away from the inner loops. !hashmap-after.png! The orange sections are the IO elevator lagging behind the map-join operator. Found other init-time lock sections, will file more JIRAs. LLAP: BytesBytesMultiHashMap does not allow concurrent read-only access --- Key: HIVE-10128 URL: https://issues.apache.org/jira/browse/HIVE-10128 Project: Hive Issue Type: Sub-task Reporter: Gopal V Assignee: Sergey Shelukhin Attachments: HIVE-10128.patch, hashmap-after.png, hashmap-sync-source.png, hashmap-sync.png The multi-threaded performance takes a serious hit when LLAP shares hashtables between the probe threads running in parallel. !hashmap-sync.png! This is an explicit synchronized block inside ReusableRowContainer which triggers this particular pattern. !hashmap-sync-source.png! Looking deeper into the code, the synchronization seems to be caused due to the fact that WriteBuffers.setReadPoint modifies the otherwise read-only hashtable. To generate this sort of result, run LLAP at a WARN log-level, to avoid all the log synchronization that otherwise affects the thread sync. -- This message was sent by Atlassian JIRA (v6.3.4#6332)
