MC2: High-Performance Garbage Collection for Memory-Constrained Environments

MC 2 : High Performance GC for Memory-Constrained Environments Narendran Sachindran J. Eliot B. Moss Emery D. Berger University of Massachusetts Amherst

Motivation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Motivation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Talk Outline ,[object Object],[object Object],[object Object],[object Object],[object Object]

Generational Collection ,[object Object],[object Object],[object Object],Nursery Old Generation

Generational Copying Collection Old Generation A B C Root D Root E D Root E Nursery Remset

Generational Copying Collection A B C Root D Root E A Root D Root B E Old Generation Nursery

MC 2 Overview ,[object Object],[object Object],[object Object],[object Object],Generational copying MC 2 Nursery Nursery Old Generation Old Generation

MC 2 – Mark Phase ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

MC 2 Example – Mark Phase ,[object Object],Old Generation Nursery L 1 L 2 L 3 L 4 Root Root L max L max Root Root Root Nursery Unreachable Reachable Marked Copied

MC 2 Example – Classify Windows ,[object Object],Old Generation Nursery L 1 L 2 L 3 L 4 Root Root L max L max Root Nursery Unreachable Reachable Marked Copied

MC 2 Example – Classify Windows Old Generation Nursery L 1 L 2 L 3 L 4 Root Root L max L max Root ,[object Object],Nursery Unreachable Reachable Marked Copied

MC 2 Example – Classify Windows Old Generation Nursery L 2 L 3 L 4 Root Root L max L max Root L max ,[object Object],Nursery Unreachable Reachable Marked Copied

MC 2 – Copy Phase ,[object Object],[object Object],[object Object],[object Object],[object Object]

MC 2 Example – Copy Phase Old Generation Nursery L max L 2 L 3 L 4 Root Root L max L max Root Root Root Root ,[object Object],Nursery Unreachable Reachable Marked Copied

MC 2 Example – Copy Phase Old Generation Nursery L max L 2 L 3 L 4 Root L max L max Root Root Root Nursery Unreachable Reachable Marked Copied ,[object Object]

MC 2 Example – Copy Phase Old Generation Nursery L 2 L 3 L 4 Root L max L max L max Root Root Root Nursery Unreachable Reachable Marked Copied ,[object Object]

MC 2 Example – Copy Phase Old Generation Nursery L max L max L max Root L max L max L max Root Root Root Nursery Unreachable Reachable Marked Copied ,[object Object]

Algorithmic Details ,[object Object],[object Object],[object Object],[object Object]

Handling large remembered sets ,[object Object],W1 W2

Handling large remembered sets ,[object Object],W1 W2 Card 1 Card 2

Handling large remembered sets ,[object Object],[object Object],[object Object]

Handling popular objects ,[object Object],[object Object],[object Object],Normal Windows Popular Window Normal Windows

Handling popular objects ,[object Object],[object Object],[object Object],Normal Window Group Popular Window Normal Window Group

Handling popular objects ,[object Object],[object Object],[object Object],[object Object]

Experimental Results ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Execution Time relative to MC 2 (Heap Size = 1.8x max. live size)

Max. Pause Time relative to MC 2 (Heap Size = 1.8x max. live size) ,[object Object]

Bounded Mutator Utilization (jess)

Bounded Mutator Utilization (javac)

Conclusions ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Traditional Tracing Collectors ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Modern incremental collectors ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Pause Time, Execution Time Comparison (80% space overhead) Benchmark MC 2 MPT (ms) MS MPT (ms) MS/MC 2 ET MSC MPT (ms) MSC/MC 2 ET _202_jess 17.2 53.2 1.11 65.7 1.04 _209_db 19.9 123.0 1.11 198.5 0.96 _213_javac 40.4 171.9 0.92 308.9 0.89 _227_mtrt 29.6 138.1 1.02 225.2 0.96 _228_jack 23.9 59.7 1.03 92.9 0.99 pseudojbb 41.5 168.2 1.08 314.5 0.98 Geo. Mean 27.2 107.7 1.04 172.7 0.97

Max. Pause Time relative to MC 2 (Heap Size = 1.8x max. live size) ,[object Object],53 66 123 199 172 309 138 225 60 93 168 315

Incremental Marking Error A B C C D

Handling marking error ,[object Object],[object Object],[object Object],[object Object]

JMTk Heap Layout Boot Image Imm. Object Space Large Object Space Old Generation Nursery

_213_javac (MSC execution time)

MC 2 Overview Old Generation Reachable data Unreachable data Copied data Free Window Free Window Free Window

MC 2 Overview Old Generation Reachable data Unreachable data Copied data Free Window Free Window Free Window Free Window Free Window Free Window

MC 2 Overview Old Generation Reachable data Unreachable data Copied data Free Window Free Window Free Window Free Window Free Window

MC2: High-Performance Garbage Collection for Memory-Constrained Environments

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MC2: High-Performance Garbage Collection for Memory-Constrained Environments