The document summarizes the Deuce software transactional memory (STM) framework for Java. Deuce allows developers to add concurrency to Java applications using atomic blocks without changing code or using reserved keywords. It works by dynamically instrumenting bytecode to enable software transactions over shared fields. Benchmarks show it scales well on multi-core systems compared to other STM approaches like TL2 and LSA that require more intrusive changes.

1. Noninvasive Java Concurrency with Deuce STM 1.0 Guy Korland “ Multi Core Tools” CMP09

3. Motivation

7. The Problem

13. Solutions III – STM Nir Shavit, DAN TOUITOU, Software Transactional Memory [PODC95] synchronized { <instructions> } atomic { <instructions> } l.lock(); <instructions> l.unlock();

15. The Brief History of STM 1993 STM (Shavit,Touitou) 2003 DSTM (Herlihy et al) 2003 WSTM (Fraser, Harris) 2003 OSTM (Fraser, Harris) 2004 ASTM (Marathe et al) 2004 T-Monitor (Jagannathan … ) 2005 Lock-OSTM (Ennals) 2004 HybridTM (Moir) 2004 Meta Trans (Herlihy, Shavit) 2005 McTM (Saha et al) 2006 AtomJava (Hindman…) 1997 Trans Support TM (Moir) 2005 TL (Dice, Shavit)) 2004 Soft Trans (Ananian, Rinard) 2006 LSA (Riegel et al 2006 TL2 (Dice, Shavit, Shalev) 2009 Deuce (Korland et al) 2008 Rock (Sun) 2006 DSTM2 (Herlihy, Luchangco) 2007 Tanger

23. Deuce - API public class Bank{ final private static double MAXIMUM_TRANSACTION = 1000; private double commission = 0; @Atomic (retries=64) public void transaction( Account ac1, Account ac2, double amount){ ac1. balance -= (amount + commission ); ac2. balance += amount; } @Atomic public void update( double value){ commission += value; } }

24. Deuce - Overview

29. Implementation @Atomic public void update ( double value){ double tmp = commission ; commission = tmp + value; } @Atomic public void update ( double value){ commission += value; } In byte code

30. Implementation public void update( double value, Context c){ double tmp; if ( commission__ADDRESS < 0 ) { // final field tmp = commission ; } else { c.beforeRead( this, commission__ADDRESS); tmp = c.onRead( this, commission , commission__ADDRESS); } c.onWrite( this, tmp + value, commission__ADDRESS); } JIT removes it

31. Implementation public void update( double value, Context c){ c.beforeRead( this, commission__ADDRESS); double tmp = c.onRead( this, commission , commission__ADDRESS); c.onWrite( this, tmp + value, commission__ADDRESS); }

32. Implementation public void update( double value){ Context context = ContextDelegetor.getContext(); for ( int i = retries ; i > 0 ; --i){ context.init (); try { update( value, context); if ( context.commit ()) return ; } catch ( TransactionException e ){ context.rollback (); continue ; } catch ( Throwable t ){ if ( context.commit ()) throw t; } } throw new TransactionException(); }

39. Benchmarks (Azul – Vega2 – 2 x 46)

40. Benchmarks (SuperMicro – 2 x Quad Intel)

41. Benchmarks (Sun UltraSPARC T2 Plus – 2 x Quad x 8 HT )