[AURORA-1847] Eliminate sequential scan in MemTaskStore.getJobKeys()

• Type: Story
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.17.0
• Component/s: Efficiency, UI
• Labels: newbie
• Epic Link: Scheduler Performance Improvement
• Assignee: Mehrdad Nurolahzade
• Reporter: Mehrdad Nurolahzade
• Created: 06/Dec/16 22:31
• Updated: 11/Jan/17 22:22
• Resolved: 11/Jan/17 22:22

Description

The existing TaskStoreBenchmarks shows DBTaskStore is almost two orders of magnitude faster than MemTaskStore when it comes to getJobKeys():

Benchmark                                       (numTasks)   Mode  Cnt       Score       Error  Units
TaskStoreBenchmarks.DBFetchTasksBenchmark.run        10000  thrpt    5  320271.082 ± 30842.727  ops/s
TaskStoreBenchmarks.DBFetchTasksBenchmark.run        50000  thrpt    5  334805.551 ± 20435.139  ops/s
TaskStoreBenchmarks.DBFetchTasksBenchmark.run       100000  thrpt    5  317395.890 ± 45302.180  ops/s
TaskStoreBenchmarks.MemFetchTasksBenchmark.run       10000  thrpt    5     624.944 ±    54.038  ops/s
TaskStoreBenchmarks.MemFetchTasksBenchmark.run       50000  thrpt    5      91.335 ±     9.241  ops/s
TaskStoreBenchmarks.MemFetchTasksBenchmark.run      100000  thrpt    5      27.712 ±     8.128  ops/s

If scheduler is configured to run with the MemTaskStore every hit on scheduler page (/scheduler) causes a call to MemTaskStore.getJobKeys().

The implementation of this method is currently very inefficient as it results in a sequential scan of the task store and then mapping to their respective job keys. The sequential scan and mapping to job key can be eliminated by simply returning the key set of the existing secondary index job.