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ATOM: Automatic Transaction-Oriented Memoization
Hugo Rito and Jo˜ ao Cachopo
INESC-ID Instituto Superior T´ ecnico
September 11, 2009
Overview of Memoization
ATOM: Automatic Transaction-Oriented Memoization Hugo Rito and Jo - - PowerPoint PPT Presentation
ATOM: Automatic Transaction-Oriented Memoization Hugo Rito and Jo - - PowerPoint PPT Presentation
ATOM: Automatic Transaction-Oriented Memoization Hugo Rito and Jo ao Cachopo INESC-ID Instituto Superior T ecnico September 11, 2009 Overview of Memoization Functional Programming Memoization Overview of Memoization Functional
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Overview of Memoization
Functional Programming
Functional Programming
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Overview of Memoization
Functional Programming
Memoization
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Overview of Memoization
Fibonacci function
static int fib(int n) { if (n <= 1) return n; return fib(n-1) + fib(n-2); }
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Overview of Memoization
fib(4) 1 4 2 1 3 1 2
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Overview of Memoization
fib(4) 1 4 2 1 3 1 2
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Overview of Memoization
fib(5) 5 3 1 2 1 1 4 2 1 3 1 2
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Overview of Memoization
fib(5) 5 3 1 2 1 1 4 2 1 3 1 2
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Overview of Memoization
fib(5) 5 3 1 2 1 1 4 2 1 3 1 2
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Overview of Memoization
Memoization Memoization
Optimization technique Function cache Relevant state − → Result
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Overview of Memoization
Memo fib(5) 5 3 1 2 1 1 4 2 1 3 1 2
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Overview of Memoization
Memo fib(5) 5 1 4 2 3
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Limitations of Memoization
Non-Functional Programming
Object-Oriented Imperative Programming
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Limitations of Memoization
Non-Functional Programming
Memoization
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Limitations of Memoization
Banking Domain
Client
Account
getTotalBalance() : long 1 * balance : long
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Limitations of Memoization
Banking Domain
class Client { Set<Account> accounts; long getTotalBalance() { long total = 0; for (Account account : accounts) { total += accounts.getBalance(); } return total; } }
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Limitations of Memoization
Banking Domain: Relevant State
class Client { Set<Account> accounts; long getTotalBalance() { long total = 0; for (Account account : accounts) { total += accounts.getBalance(); } return total; } }
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Limitations of Memoization
Banking Domain: Relevant State
class Client { Set<Account> accounts; long getTotalBalance() { long total = 0; for (Account account : accounts) { total += accounts.getBalance(); } return total; } }
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Limitations of Memoization
Relevant State: Problem
No automatic solutions
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Limitations of Memoization
Relevant State: Problem
No automatic solutions Manually
Difficult Error-prone
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Limitations of Memoization
Side-effects
Share state reads difficult...
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Limitations of Memoization
Side-effects
Share state reads difficult... and side-effects make it worse!
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Proposed Solution
Proposed Solution
Memoization
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Proposed Solution
Proposed Solution
Memoization + Software Transactional Memory
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Proposed Solution
Proposed Solution
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Proposed Solution
Proposed Solution
Automatic Transaction-Oriented Memoization
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Proposed Solution
Proposed Solution
Object-Oriented Imperative Programming
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Proposed Solution
Proposed Solution
Automatic Transaction-Oriented Memoization
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Proposed Solution
Software Transactional Memory
Concurrent programming
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Proposed Solution
Software Transactional Memory
Concurrent programming Transaction
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Proposed Solution
Software Transactional Memory
Concurrent programming Transaction Intercept accesses
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Proposed Solution
Software Transactional Memory
Concurrent programming Transaction Intercept accesses Read-set / Write-set
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Proposed Solution
JVSTM Example
class Client { Set<Account> accounts; long getTotalBalance() { long total = 0; for (Account account : accounts) { total += accounts.getBalance(); } return total; } }
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Proposed Solution
JVSTM Example
class Client { VSet<Account> accounts; long getTotalBalance() { long total = 0; for (Account account : accounts) { total += accounts.getBalance(); } return total; } }
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Proposed Solution
JVSTM Example
class Client { VSet<Account> accounts; long getTotalBalance() { long total = 0; for (Account account : accounts.get()) { total += accounts.getBalance(); } return total; } }
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Proposed Solution
JVSTM Example
class Client { VSet<Account> accounts; @Atomic long getTotalBalance() { long total = 0; for (Account account : accounts.get()) { total += accounts.getBalance(); } return total; } }
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Proposed Solution
The ATOM
Java library
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Proposed Solution
The ATOM
Java library Uses an STM to..
Build the relevant state Detect side-effects Capture side-effects
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Proposed Solution
The ATOM
Java library Uses an STM to..
Build the relevant state Detect side-effects Capture side-effects
Simple interface
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Proposed Solution
Evolution
Cache Search Cache Hit? Execute Method Add New Cache Entry Get Result From Cache Yes No
Memoization
Return Result
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Proposed Solution
Evolution
Cache Search Cache Hit? Execute Method Add New Cache Entry Get Result From Cache Yes No
Extended Memoization
Return Result Begin Transaction Commit Transaction
Read-set: Relevant state Write-set: Side-effects
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Proposed Solution
Evolution
Cache Search Cache Hit? Commit Transaction Execute Method Add New Cache Entry Get Result From Cache Yes No
Extended Memoization
Begin Transaction Return Result Yes No Can Memoize? Collect Information
Two memoization strategies: Read-only Write-allowed “Collect Information” caches: Read-set Possibly the write-set
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Proposed Solution
Evolution
Cache Search Cache Hit? Commit Transaction Execute Method Add New Cache Entry Get Result From Cache Yes No
Extended Memoization
Begin Transaction Return Result Read Only? Yes No Can Memoize? Collect Information Yes No Apply Changes
Possibly apply the write-set
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Proposed Solution
Evolution
Cache Hit? Commit Transaction Execute Method Add New Cache Entry Get Result From Cache Yes No
Extended Memoization
Begin Transaction Return Result Read Only? Yes No Apply Changes Can Memoize? Collect Information Yes No Cache Search
Two caching policies: Version Value
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Proposed Solution
ATOM Example
@Atomic long getTotalBalance() { /* Body of getTotalBalance() */ }
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Proposed Solution
ATOM Example
@Memo long getTotalBalance() { /* Body of getTotalBalance() */ }
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Experimental Results
STMBench7 benchmark
Customizable Evaluate STM implementations CAD domain
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Experimental Results
Experimental Setting
Dual-Quadcore Nehalem Xeon, 12Gb of RAM 1, 2, 4, 8, and 16 threads Read-dominated workload Three mixes of operations
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Experimental Results
Results
1 2 4 8 16 1000 2000 3000 4000 5000 6000
No read-write traversals / No structural modifications
ATOM JVSTM
Number of Threads O p e r a t i
- n
s / s e c
- n
d
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Experimental Results
Results
1 2 4 8 16 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
No traversals
ATOM JVSTM
Number of Threads O p e r a t i
- n
s / s e c
- n
d
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Experimental Results
Results
1 2 4 8 16 5000 10000 15000 20000 25000
No traversals / No structural modifications
ATOM JVSTM
Number of Threads O p e r a t i
- n
s / s e c
- n
d
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Conclusions
Summary
Memoize object-oriented imperative programs is hard
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Conclusions
Summary
Memoize object-oriented imperative programs is hard ATOM
Relevant state dynamically constructed Detects/Integrates side-effects Simple interface
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Conclusions
Summary
Memoize object-oriented imperative programs is hard ATOM
Relevant state dynamically constructed Detects/Integrates side-effects Simple interface
Memoization improves STMs’ performance
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Conclusions