Debugging at Full Speed

Transcription

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2 Oracle Labs Document Debugging at Full Speed Instrumen)ng Truffle- implemented Programs Michael L. Van De Vanter Oracle Labs, VM Research Group July 30, JVM Language Summit Santa Clara, CA July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed

3 Safe Harbor Statement The following is intended to provide some insight into a line of research in Oracle Labs. It is intended for informaron purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or funcronality, and should not be relied upon in making purchasing decisions. Oracle reserves the right to alter its development plans and pracrces at any Rme, and the development, release, and Rming of any features or funcronality described in connecron with any Oracle product or service remains at the sole discreron of Oracle. Any views expressed in this presentaron are my own and do not necessarily reflect the views of Oracle. July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 3

4 The Big Idea Extend the Truffle/Graal playorm, which enables high- performance implementarons of dynamic languages (Ruby, R, JavaScript, Python, Smalltalk) with reduced implementaron effort by building in instrumenta*on support that enables flexible access to Truffle execuron events by many kinds of tools (debuggers, profilers, etc.) with minimal runrme overhead requiring modest implementaron effort. July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 4

5 InstrumenRng Truffle Programs Truffle: ExecuRon Overview Tools: Opportunity, Challenge, Strategy Proof of Concept: Ruby, Ruby debugger Truffle: new InstrumentaRon API ApplicaRons & Status July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 5

6 Truffle node specializaron U Node Rewriting for Profiling Feedback G Compilation using Partial Evaluation G U U Node Transitions I G I G U U U Uninitialized Integer I I I I I AST Interpreter Uninitialized Nodes S String G D Double Generic AST Interpreter Rewritten Nodes Compiled Code T. Würthinger, C. Wimmer, A. Wöß, L. Stadler, G. Duboscq, C. Humer, G. Richards, D. Simon, and M. Wolczko. One VM to rule them all. In Proceedings of Onward, July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 6

7 Truffle deoprmizaron and rewrirng Deoptimization to AST Interpreter G Node Rewriting to Update Profiling Feedback G Recompilation using Partial Evaluation G G I G I G D G D G I I I D I I I D T. Würthinger, C. Wimmer, A. Wöß, L. Stadler, G. Duboscq, C. Humer, G. Richards, D. Simon, and M. Wolczko. One VM to rule them all. In Proceedings of Onward, July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 7

8 GraalVM Architecture Guest Language Application Guest Language Implementation Language Parser AST Interpreter Truffle API Framework for Node Rewriting Truffle Optimizer Partial Evaluation using Graal Hosted on any Java VM VM Runtime Services Garbage Collector Graal Compiler Stack Walking Deoptimization AOT Optimization: using Graal for static analysis and AOT compilation OS (slow, for guest language development and debugging only) Hosted on Graal VM (fast, for integration of guest language code with existing Java applications) T. Würthinger, C. Wimmer, A. Wöß, L. Stadler, G. Duboscq, C. Humer, G. Richards, D. Simon, and M. Wolczko. One VM to rule them all. In Proceedings of Onward, July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 8

9 InstrumenRng Truffle Programs Truffle: ExecuRon Overview Tools: Opportunity, Challenge, Strategy Proof of Concept: Ruby, Ruby debugger Truffle: new InstrumentaRon API ApplicaRons & Status July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 9

10 Opportunity: Tool Access to Truffle RunRme Language implementarons relarvely accessible All Java Wrinen as interpreters ExecuRon state represented explicitly: stack, frames, Truffle/Graal op*mizes and deop*mizes Many aggressive oprmizarons down to narve code For its own purposes can deop*mize Reconstruct execuron state completely July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 10

11 Challenge: Blend with Truffle Define language- agnosrc services Automate as much tool support as possible Leverage Truffle/Graal oprmizarons E.g. breakpoint condirons should fully oprmize Unused framework should compile away Minimize disrupron Language implementaron code Truffle oprmizarons Simple API for tool clients July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 11

12 Strategy: Interpose with Node Wrappers Insert addironal nodes into Truffle ASTs (wrappers) Anachment points for tool interposiron SemanRcally transparent during execuron Largely orthogonal to language implementaron Can be composed Focus on language execuron semanrcs No access (for now) to low- level state, e.g. memory July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 12

13 InstrumenRng Truffle Programs Truffle: ExecuRon Overview Tools: Opportunity, Challenge, Strategy Proof of Concept: Ruby, Ruby debugger Truffle: new InstrumentaRon API ApplicaRons & Status July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 13

14 Tools: The Debugger Challenge They are difficult to build Oren Rghtly coupled to narve playorms Cross many levels of system abstracrons Contend with incomplete access to execuron state They present significant producrvity tradeoffs Performance disabled oprmizarons FuncRonality inhibited language features Complexity language implementaron requirements Inconvenience nonstandard context (debug flags) July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 14

15 Wrapper Nodes While Call < Sequence 1""""while"x"<"y" 2""""""x"+="1" 3""""""y"*="1" 4""""end( ReadLocal x ReadLocal y WriteLocal x Call + ReadLocal x FixnumLiteral 1 WriteLocal y Call - ReadLocal y FixnumLiteral 1 July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 15

16 While LineBreakpoint Sequence Call < LineBreakpoint ReadLocal x WriteLocal x ReadLocal y Call + ReadLocal x FixnumLiteral 1 LineBreakpoint WriteLocal y Call - ReadLocal y FixnumLiteral 1 July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 16

17 Ruby Prototype (Chris Seaton) AcRve/InacRve AcRons Inactive assumption check completely elided in compiled code Debug action installed by user inactive active Compile: produces partially evaluated machine code from specialized AST. Deoptimize: transfers control from the machine code back to the AST interpreter. Replace: the inactive node with an active node to install the debug action Compile: produces new machine code from the modified AST and the installed debug action. July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 17

18 Ruby Prototype: set_trace_func 1""""set_trace_func"proc"{" event,"file,"line," 2""""""""id,"binding,"classname " 3""""""puts""We're"at"line"number"#{line}"" 4""""}" Standard Ruby language feature Uses: debuggers, profilers, coverage Enabled and disabled programmarcally Naïve implementaron: check for it every single Rme a bytecode has a different line number Rubinius doesn t support it at all, JRuby has it behind a flag July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 18

19 While InactiveTrace Sequence Call < InactiveTrace ReadLocal x WriteLocal x ReadLocal y Call + ReadLocal x FixnumLiteral 1 InactiveTrace WriteLocal y Call - ReadLocal y FixnumLiteral 1 July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 19

20 While Call trace func ActiveTrace Call < Sequence ActiveTrace ReadLocal x WriteLocal x Call trace func ReadLocal y Call + ReadLocal x FixnumLiteral 1 ActiveTrace WriteLocal y Call trace func Call - ReadLocal y FixnumLiteral 1 July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 20

21 Ruby Prototype: BuilRn Debug OperaRons 1""""100.times"do' 2"""""Debug.break" 3""""end' 1""""Debug.break("test.rb","14)"do( 2"""""puts""The"program"has"reached"line"14"" 3""""end( 1""""Debug.break("test.rb","14)"do" binding " 2""""""if"binding.local_variable_get(:foo)"=="14" 3""""""""Debug.break" 4""""""end' 5""""end' July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 21

22 EvaluaRon general performance Speedup Relative to MRI (s/s) Fannkuch Mandelbrot 0 MRI Rubinius JRuby Topaz JRuby+Truffle Chris Seaton, Michael Van De Vanter, Michael Haupt. Debugging at Full Speed. In Proceedings of DYLA July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 22

23 EvaluaRon summary Self Relative Time (s/s) MRI Rubinius JRuby Topaz JRuby+Truffle 1 n/a Enabling set_trace_func n/a Using set_trace_func n/a Enabling debugger n/a Breakpoint n/a Constant conditional n/a Simple conditional Chris Seaton, Michael Van De Vanter, Michael Haupt. Debugging at Full Speed. In Proceedings of DYLA July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 23

24 InstrumenRng Truffle Programs Truffle: ExecuRon Overview Tools: Opportunity, Challenge, Strategy Proof of Concept: Ruby, Ruby debugger Truffle: new InstrumentaRon API ApplicaRons & Status July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 24

25 Generalize, Scale, Simplify Ruby prototype: Extensions (builrns) to guest language FuncRon- specific wrappers MulRple, chained wrappers Wrappers only added starcally AcRvate tool funcrons via node replacement InstrumentaRon API: Language- agnosrc API for tools General purpose wrappers Single wrapper per locaron Add mulrple tool funcrons dynamically AcRvate tool funcrons by state changes July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 25

26 Language ImplementaRon API Define language- specific wrapper node type(s) Wrap appropriate nodes when ASTs constructed Ensure complete source a3ribu*on By default, Probes are tracked by source locaron AddiRonal tool- specific support (e.g. debugging) E.g. eval July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 26

27 Tool Client API: Overview Disclaimer: work in progress SourceSecRon Text range corresponding to a user- sensible AST node SyntaxTag AnnotaRon to guide tool behavior at an AST node (e.g. STMT) ExecuRonEvent Flow of control into or out of an AST node Instrument Tool- specific receptor of ExecuRonEvents at an AST node Probe Manager for Instruments & SyntaxTags at an AST node July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 27

28 Tool Client API: A Truffle Instrument Interposes in Truffle interpreta)on public abstract class Instrument implements ExecutionEvents { public void enter(node node, Frame frame) { } public void leave(node node, Frame frame) { } public void leave(node node, Frame frame, Object result) { } public void leave(node node, Frame frame, boolean result) { leave(node, frame, (Object) result); }... public void leaveexceptional(node node, Frame frame, Exception e) { } } July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 28

29 Tool Client API: A Truffle Probe Manages Instruments & Tags at an AST loca)on public interface Probe { void addinstrument(instrument newinstrument); void removeinstrument(instrument oldinstrument); void tagas(syntaxtag tag); } public interface ProbeListener { void newprobeinserted(sourcesection location, Probe probe); void probetaggedas(probe probe, SyntaxTag tag); } July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 29

30 Tool Client API: Finding Probes Dynamically public abstract class ExecutionContext { Probe getprobe(sourcesection sourcesection); Collection<Probe> findprobestaggedas(syntaxtag tag); Collection<Probe> findprobesbyline(linelocation linelocation);... } July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 30

31 InstrumenRng Truffle Programs Truffle: ExecuRon Overview Tools: Opportunity, Challenge, Strategy Proof of Concept: Ruby, Ruby debugger Truffle: new InstrumentaRon API ApplicaRons & Status July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 31

32 ApplicaRon: Language ImplementaRon Ruby implementa)on by Chris Seaton Ruby set_trace_function Invokes arbitrary proc at each statement Ruby heap iteraron, possibly filtered ObjectSpace.each_object() ObjectSpace.count_objects() ObjectSpace._id2ref(object_id) Ruby core library thread quiescence Implemented with Instruments July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 32

33 ApplicaRon: Simple Profiling Collabora)on with UC Irvine ZipPy performance oprmizarons Exploratory work to locate hot spots Gathering interpreter- level execuron data Building maps when needed July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 33

34 ApplicaRon: Debugging (1/3) Very limited, but useful func)onality Debugging engine prototype Breakpoints; step in/over/out; show frame vars; backtrace Evaluate string in halted context Language- agnosrc (mostly) Language- specific adaptaron Some language- specific code needed Ruby, JavaScript working at same funcronal level Simple (demonstraron language) underway R just begun July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 34

35 ApplicaRon: Debugging (2/3) public final class DebugBreakInstrument extends DebugInstrument private boolean isenabled = true; public DebugBreakInstrument(DebugInstrumentCallback callback) { super(callback); public void enter(node astnode, VirtualFrame frame) { if (isenabled) { debuggercallback.haltedat(astnode, frame.materialize()); } }... } July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 35

36 ApplicaRon: Debugging (3/3) Command- Line debugger for tesrng & demonstraron Client/server architecture emulated Client is language- agnosrc Server built around a language- specific Debugging Engine IDE integraron Looking at simple experiments with NetBeans July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 36

37 Status InstrumentaRon is part of the public Truffle API Debugging is under internal development July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 37

38 July 30, 2014 Copyright 2014, Oracle and/or its affiliates. All rights reserved. JVM Language Summit- Debugging at Full Speed 38

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