Table Of ContentUNIVERSITY OF OSLO
Department of Informatics
Investigating
Different
Concurrency
Mechanisms in
Java
Master thesis
Petter Andersen
Busterud
August 2012
Abstract
With the continual growth in number of cores on the Central Processing
Unit (CPU), developers will need to focus more and more on concurrent
programming to get the desired performance boost that in the past have
comelogicallywiththeincreasedclock-rate.
Today there are numerous of different libraries and mechanisms for
synchronization and parallelization in Java, and in this thesis we will
attempttotesttheefficiencyandruntimeoftwodifferenttypesofsorting
algorithms on machines with multi-core processors using the concurrent
toolsprovidedbyJava.
We will also be looking into the overhead that occur by using the various
mechanisms, to help establish the correlations between the mechanisms
overheadandperformancegain.
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Acknowledgement
This thesis concludes my Master’s Degree in Informatics: Programming
and Networks with the Department of Informatics at the University of
Oslo. Ithasbeenalonganddifferent,butpositiveexperience.
FirstIwanttothankmysupervisorArneMaus,whoofferedmethisthesis
andhavebeenprovidingvaluablefeedbackalongtheway.
Ialsoliketothankmyfriendsandfamilywhohasbeenpatientwithmeall
theseyears,andthesupportandencouragementtheygivenmethroughout
thisperiod.
UniversityofOslo,August2012
PetterAndersenBusterud
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Contents
1 Introduction 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 ThesisOutline . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 ConcurrencyandThreadsinJava 5
2.1 ConcurrencyConcepts . . . . . . . . . . . . . . . . . . . . . . 6
2.2 ConcurrencyinJava . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.1 ThreadPool,aTaskExecutionFramework . . . . . . . 8
2.2.2 Future . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.3 Atomicity . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.4 Locks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.5 QueueandDeque . . . . . . . . . . . . . . . . . . . . 11
2.2.6 Synchronize . . . . . . . . . . . . . . . . . . . . . . . . 12
2.2.7 Fork/Join . . . . . . . . . . . . . . . . . . . . . . . . . 13
3 TestEnvironment 15
3.1 TestDataStructure . . . . . . . . . . . . . . . . . . . . . . . . 15
3.1.1 GeneratingData . . . . . . . . . . . . . . . . . . . . . 16
3.2 Benchmarking . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.1 Method. . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.2 MedianorAverage . . . . . . . . . . . . . . . . . . . . 19
3.3 HardwareandSoftware . . . . . . . . . . . . . . . . . . . . . 20
3.3.1 Specification . . . . . . . . . . . . . . . . . . . . . . . . 21
3.3.2 Cache . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.4 JavaVirtualMachine(JVM) . . . . . . . . . . . . . . . . . . . 23
3.4.1 Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4 SortingAlgorithms 25
4.1 WhichSortingAlgorithms . . . . . . . . . . . . . . . . . . . . 25
4.2 Quicksort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
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4.2.1 Implementation . . . . . . . . . . . . . . . . . . . . . . 27
4.2.2 TestRun . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3 LSD-Radixsort . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3.1 Implementation . . . . . . . . . . . . . . . . . . . . . . 30
4.3.2 TestRun . . . . . . . . . . . . . . . . . . . . . . . . . . 32
5 Experiments 33
5.1 ParallelQuicksortImplementations . . . . . . . . . . . . . . 33
5.1.1 Naive . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
5.1.2 ExecutorService . . . . . . . . . . . . . . . . . . . . . . 37
5.1.3 Fork/Join . . . . . . . . . . . . . . . . . . . . . . . . . 39
5.2 ParallelLSD-RadixsortImplementations . . . . . . . . . . . . 41
5.2.1 CyclicBarrierandAtomicity . . . . . . . . . . . . . . . 42
5.2.2 Non-AtomicwithDuplicateReads . . . . . . . . . . . 45
5.2.3 Non-AtomicwithDuplicateData . . . . . . . . . . . 47
5.3 TestCaseswithmoreCores . . . . . . . . . . . . . . . . . . . 50
5.3.1 Java7UtilitieswhenusingJava6. . . . . . . . . . . . 50
5.3.2 QuicksortTestRuns . . . . . . . . . . . . . . . . . . . 51
5.3.3 LSD-RadixsortTestRuns . . . . . . . . . . . . . . . . 53
6 ThreadsandOverhead 55
6.1 MeasurementMethod . . . . . . . . . . . . . . . . . . . . . . 56
6.1.1 TestProgramStructure . . . . . . . . . . . . . . . . . . 56
6.1.2 WindowsandBatch-file . . . . . . . . . . . . . . . . . 57
6.1.3 LinuxandBash-file . . . . . . . . . . . . . . . . . . . . 59
6.1.4 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.2 OverheadTestResults . . . . . . . . . . . . . . . . . . . . . . 60
6.2.1 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.2.2 Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
6.2.3 Threads . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6.2.4 ExecutorService . . . . . . . . . . . . . . . . . . . . . . 64
6.2.5 Fork/Join . . . . . . . . . . . . . . . . . . . . . . . . . 65
6.2.6 Atomicity . . . . . . . . . . . . . . . . . . . . . . . . . 66
6.3 Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
7 Discussion 69
7.1 Amdahl’sLaw . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
7.2 TestResultsDiscussion . . . . . . . . . . . . . . . . . . . . . . 71
8 Conclusions 73
8.1 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
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List of Figures
2.1 Work-Stealing . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.1 NehalemArchitecture . . . . . . . . . . . . . . . . . . . . . . 21
3.2 CacheLatency . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1 SequentialQuicksort . . . . . . . . . . . . . . . . . . . . . . . 29
4.2 LSD-/MSD-Radixsort . . . . . . . . . . . . . . . . . . . . . . 30
4.3 SequentialRadixsort . . . . . . . . . . . . . . . . . . . . . . . 32
5.1 ParallelNaiveQuicksort . . . . . . . . . . . . . . . . . . . . . 36
5.2 ParallelQuicksortusingExecutorService . . . . . . . . . . . 39
5.3 ParallelQuicksortusingFork/Join . . . . . . . . . . . . . . . 41
5.4 ParallelRadixsortusingCyclicBarrierandAtomicity . . . . 44
5.5 ParallelRadixsortwithDuplicateReads . . . . . . . . . . . . 47
5.6 ParallelRadixsortwithDuplicateData . . . . . . . . . . . . . 49
5.7 SequentialQuicksortonthe32-coreCPU . . . . . . . . . . . 51
5.8 ParallelNaiveQuicksortwith32-cores(64w/HT) . . . . . . 51
5.9 ParallelQuicksortusingExecutorService;32-cores(64w/HT) 52
5.10 ParallelQuicksortusingFork/Join;32-cores(64w/HT) . . . 52
5.11 SequentialRadixsortonthe32-coreCPU. . . . . . . . . . . . 53
5.12 ParallelRadixsortusingCyclicBarrierandAtomicity;32-cores 53
5.13 ParallelRadixsortwithDuplicateReads;32-cores(64w/HT) 54
5.14 ParallelRadixsortwithDuplicateData;32-cores(64w/HT) 54
6.1 ComparisonofTotalRunTimes(inµs) . . . . . . . . . . . . . 68
6.2 QuicksortSortingTimes . . . . . . . . . . . . . . . . . . . . . 68
7.1 Amdahl’sLaw . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
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Description:attempt to test the efficiency and run time of two different types of sorting algorithms on machines with multi-core processors using the concurrent.
