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intg/src/main/java/org/apache/atlas/utils/FixedBufferList.java Lines 59 (patched) <https://reviews.apache.org/r/72666/#comment310410> set length to 0 here? this.length = 0; repository/src/main/java/org/apache/atlas/repository/audit/EntityAuditListenerV2.java Lines 81 (patched) <https://reviews.apache.org/r/72666/#comment310411> withInitial() be called only on the first access from a thread. Calling reset() from here is not useful. repository/src/main/java/org/apache/atlas/repository/audit/EntityAuditListenerV2.java Line 93 (original), 100 (patched) <https://reviews.apache.org/r/72666/#comment310412> AUDIT_EVENTS_BUFFER.get() will not call ThreadLocal.withInitial(), hence will not have the list reset - #81. As suggested earlier, consider using a method like: FixedBufferList<EntityAuditEventV2> getAuditEventsList() { FixedBufferList<EntityAuditEventV2> ret = AUDIT_EVENTS_BUFFER.get(); ret.reset(); return ret; } webapp/src/main/java/org/apache/atlas/notification/EntityNotificationSender.java Line 127 (original), 127 (patched) <https://reviews.apache.org/r/72666/#comment310413> This file has only whitespace changes. Please revert. - Madhan Neethiraj On July 30, 2020, 5:55 p.m., Ashutosh Mestry wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > https://reviews.apache.org/r/72666/ > ----------------------------------------------------------- > > (Updated July 30, 2020, 5:55 p.m.) > > > Review request for atlas, Madhan Neethiraj, Nikhil Bonte, Nixon Rodrigues, > and Sarath Subramanian. > > > Bugs: ATLAS-3878 > https://issues.apache.org/jira/browse/ATLAS-3878 > > > Repository: atlas > > > Description > ------- > > **Background** > See JIRA for details. > > *Analysis* Using memory profiling tools, it was observed that large number of > notification objects were created. These stayed in memory and later were > promoted to higher generation, thereby taking even longer to be collected. > > **Approach** > Using the fixed-buffer approach to address the problem of creating large > number of small objects. > > New *FixedBufferList* This is an encapsulation over *ArrayList*. During > initial allocation, list is populated with default values. Features: > - Setting of values to these pre-allocated objects is achieved by first doing > a *get* on the element and then assigning values to it. > - *toList* fetches the sub-list from the encapsulating list. This uses the > state within the class to fetch the right length for the returning array. > > New *NamedFixedBufferList* Maintains a per-thread *FixedBufferList*. This is > necessary since the list is now part class's state. > Modified *EntityAuditListenerV2* Uses the new classes. > Modifed *EntityNotificationListener* Uses the new classes. > > **Verification** > - Using the test setup, the memory usage was observed over a period of 24 > hrs. > - Memory usage and object allocation was obvserved using memory profiler. > > > Diffs > ----- > > intg/src/main/java/org/apache/atlas/AtlasConfiguration.java 2c007ca01 > intg/src/main/java/org/apache/atlas/model/Clearable.java PRE-CREATION > intg/src/main/java/org/apache/atlas/model/audit/EntityAuditEventV2.java > 63116d467 > intg/src/main/java/org/apache/atlas/utils/FixedBufferList.java PRE-CREATION > intg/src/test/java/org/apache/atlas/utils/FixedBufferListTest.java > PRE-CREATION > > repository/src/main/java/org/apache/atlas/repository/audit/EntityAuditListenerV2.java > 79527acfa > > webapp/src/main/java/org/apache/atlas/notification/EntityNotificationSender.java > c2ae5122b > > > Diff: https://reviews.apache.org/r/72666/diff/10/ > > > Testing > ------- > > **Unit testing** > Unit tests added for the new classes. > > **Volume testing** > Setup: > - Node: Threads 40, Core: 40, Allocated Memory: 12 GB > - Multiple Kafka queues ingesting data. > - Bulk entity creation using custom script ingesting 100M entities. > > Memory usage stayed between 0 and 5% during the 24 hr period. > > With: > - Workers: 64 > - Batch size: 50 (fewer elements in batch improve commit time and audit write > time). > - Throughput: ~1.2 M entities per hour. Without out of memory error. > > **Pre-commit** > https://builds.apache.org/view/A/view/Atlas/job/PreCommit-ATLAS-Build-Test/2035/ > https://builds.apache.org/view/A/view/Atlas/job/PreCommit-ATLAS-Build-Test/2067/ > > > Thanks, > > Ashutosh Mestry > >