Poly/ML

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711 discussions

Assertion `val.IsDataPtr()' failed
by alex.merry＠cs.ox.ac.uk 01 Jul '11

01 Jul '11

I think Lucas has probably mentioned this problem that we keep running into with quantomatic. I'm using Poly/ML 5.4 (ie: the lastest version of the 5.4 branch from subversion). Occasionally (or, in my case, frequently) we get the following error: poly: scanaddrs.cpp:107: PolyWord ScanAddress::ScanStackAddress(PolyWord, StackObject*, bool): Assertion `val.IsDataPtr()' failed. There appears to be no rhyme or reason to it. Re-running poly with the same code another time will not necessarily produce this assertion, or may produce it in a different place. It happens regardless of compiler optimisations (I've tried -O3, -O2 and -O0). I managed to get a backtrace: #0 0x0000003ff54330c5 in raise () from /lib64/libc.so.6 #1 0x0000003ff5434a76 in abort () from /lib64/libc.so.6 #2 0x0000003ff542b905 in __assert_fail () from /lib64/libc.so.6 #3 0x00007ffff7dc357e in ScanAddress::ScanStackAddress (this=0x7fffffffde10, val=..., base=0x7fffed6b56c0, isCode=false) at scanaddrs.cpp:107 #4 0x00007ffff7dc3811 in ScanAddress::ScanAddressesInObject (this=0x7fffffffde10, obj=0x7fffed6b56c0, lengthWord=4827858800541175088) at scanaddrs.cpp:146 #5 0x00007ffff7d9b4e2 in ProcessMarkPointers::ScanAddressesInObject (this=0x7fffffffde10, base=0x7fffed6b56c0, L=4827858800541175088) at gc.cpp:509 #6 0x00007ffff7dc42c8 in ScanAddress::ScanAddressesInObject (this=0x7fffffffde10, base=0x7fffed6b56c0) at scanaddrs.h:86 #7 0x00007ffff7dc3d48 in ScanAddress::ScanAddressesInRegion (this=0x7fffffffde10, region=0x7fffed6a3af0, end=0x7fffed6c3000) at scanaddrs.cpp:252 #8 0x00007ffff7d9ad12 in OpMutables (process=0x7fffffffde10) at gc.cpp:348 #9 0x00007ffff7d9d2cc in doGC (doFullGC=false, wordsRequiredToAllocate=3) at gc.cpp:1341 #10 0x00007ffff7d9f473 in QuickGCRequest::Perform (this=0x7fffeaa10cc0) at gc.cpp:1955 #11 0x00007ffff7da732c in Processes::BeginRootThread (this=0x7ffff7ffa8e0, rootFunction=0x605278) at processes.cpp:1253 #12 0x00007ffff7d9a472 in polymain (argc=3, argv=0x7fffffffe218, exports=0xf72a00) at mpoly.cpp:205 #13 0x0000000000400659 in main (argc=3, argv=0x7fffffffe218) at polystub.c:43 I don't know how useful that is, though. Alex

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Repeated ascriptions
by aleks0＠gmail.com 28 Jun '11

28 Jun '11

Why are repeated signature ascriptions slow? Suppose Foo is a pretty big structure, which has already been ascribed the signature FOO: > structure X = Foo; (* fast, note that poly already knows Foo, and thus X, is a FOO *) structure X : FOO > structure X = Foo : FOO (* slow *) structure X : FOO > structure X : FOO = Foo (* slow *) structure X : FOO Poly already knows that Foo is a FOO, so surely this should return instantly, but it acts like its typechecking the whole struct again. While it's not necessary to do the ascriptions above (poly is smart enough to figure out X is a FOO, even in the first case), this same issue seems to be seriously slowing down functor evaluation, where you can't avoid ascription. I thought using opaque ascription might skirt the issue, but the same thing happens. Is poly just being silly, or this this a consequence of how the type system works? a

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Nice parallelisation examples in poly/ML
by aleks0＠gmail.com 23 Jun '11

23 Jun '11

Hello polyglots, I was wondering, do any of you have some little examples or chunks of code that do some parallel computation, possibly using some of the code in Isabelle's "Pure/Concurrent" dir? Say, for instance, I have a stack of names and an (expensive) function from names to bools. I'd like to spawn a handful of workers and wait for them to finish. The workers then pop names off, compute the boolean function and push the names back on to "true" and "false" stacks. This kind of setup should be pretty straightforward to implement, but a few pointers as far as what structs to use and how to use them would be useful. Thanks! Aleks

2 4

IEEE reals
by David.Matthews＠prolingua.co.uk 17 Jun '11

17 Jun '11

I've fixed a bug that Grant Passmore reported where the IEEEReal.setRoundingMode settings weren't working on X86. I've written a small regression test for this particular case but it would be nice to test Poly/ML's real numbers more completely. I'm not that familiar with real number arithmetic and even less so with the rather arcane areas of IEEE reals. Is there anyone who could provide some more tests for this part of Poly/ML? It may be that there are some tests available in another language that could be adapted, perhaps as a student project. David

2 1

Thread Status Flags
by dathayer＠microsoft.com 10 Jun '11

10 Jun '11

Dave, I do have one more question. You stated that >Poly/ML currently uses a single word for these. The mapping is >1 -> Broadcast >OR-ed with: >2 -> Synch >4 -> Asynch >6 -> AsynchOnce Where is the InterruptDefer flag status stored? David

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Semantics of Threading Intrrupt Flags and proper interpretation in .Net simulation
by dathayer＠microsoft.com 10 Jun '11

10 Jun '11

Dave, Thank you I believe I have the necessary information now to generate a workable simulation of your Thread.SML in F#. David Date: Tue, 07 Jun 2011 17:55:11 +0100 From: David Matthews <David.Matthews(a)prolingua.co.uk> To: polyml(a)inf.ed.ac.uk Subject: Re: [polyml] Semantics of Threading Intrrupt Flags and proper interpretation in .Net simulation Message-ID: <4DEE57EF.30709(a)prolingua.co.uk> In-Reply-To: <717F714B587F944C88837A99AA4D0081404C275E(a)TK5EX14MBXC116.redmond.corp.microsoft.com> References: <717F714B587F944C88837A99AA4D0081404C275E(a)TK5EX14MBXC116.redmond.corp.microsoft.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: list Message: 3 Hi David, On 06/06/2011 23:48, Dave Thayer wrote: > My questions are > > 1. What is the semantics of these flags as related to the behavior of threads and the Interrupt signal? Have you looked at http://www.polyml.org/docs/Threads.html ? There's an explanation there. If it's not clear please let me know. This is really one of the most problematic bits of the threading model in Poly/ML. > > 2. Can a single word be used to model these flags thusly (see below) given that I am using a completely different runtime than what you are calling into? > 1 -> InterruptDefer > 2 -> InterruptSynch > 4 -> InterruptAsynch > 6 -> InterruptAsynchOnce > 8 -> BroadcastInterrupt Poly/ML currently uses a single word for these. The mapping is 1 -> Broadcast OR-ed with: 2 -> Synch 4 -> Asynch 6 -> AsynchOnce It's actually in the second word of a 4-word thread object. The first word is a tagged integer which is an index into the thread table in the run-time system, the third points to a list of thread-local data and the fourth is a "hint" used in interrupt handling. Regards, David ------------------------------ _______________________________________________ polyml mailing list polyml(a)inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/polyml End of polyml Digest, Vol 69, Issue 2 ************************************* -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

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Semantics of Threading Intrrupt Flags and proper interpretation in .Net simulation
by dathayer＠microsoft.com 07 Jun '11

07 Jun '11

Dave Matthews, I am building a thread manager for the .NET CLR that emulates your threading model in Poly ML I am a little confused by a couple of issues in your file Basis/Thread.Sml You have a set of associated types declared as such datatype threadAttribute = EnableBroadcastInterrupt of bool | InterruptState of interruptState and interruptState = InterruptDefer | InterruptSynch | InterruptAsynch | InterruptAsynchOnce You then create functions for writing these into a tuple of words as bit flags With the following mapping 1 -> InterruptDefer 2 -> InterruptSynch 4 -> InterruptAsynch 6 -> InterruptAsynchOnce And then mapping the lowest bit of the other word in the tuple to the flag in EnableBroadcastInterrupt My questions are 1. What is the semantics of these flags as related to the behavior of threads and the Interrupt signal? 2. Can a single word be used to model these flags thusly (see below) given that I am using a completely different runtime than what you are calling into? 1 -> InterruptDefer 2 -> InterruptSynch 4 -> InterruptAsynch 6 -> InterruptAsynchOnce 8 -> BroadcastInterrupt I now you don't get many questions from people working with the CLR so I appreciate your patience David Thayer

2 1

Memory leak? Poly/ML SVN 1307
by aleks0＠gmail.com 07 Jun '11

07 Jun '11

I've just updated to the latest SVN of poly, and my compile times have ballooned up. Prodding it a bit, it looks to me like there's a memory leak in the interpreter. Here's what I do to get it to happen: 1. Fire up poly and load a modest heap (59 megs) containing about 100 structures and functors. top shows poly's RAM usage goes to a little over 59 megs. 2. Run some pretty functor-heavy code, including some code that looks (essentially) like this: structure Structure1 = Functor1(....); structure Structure2 = Functor2(structure Foo = Structure1); structure Structure3 = struct open Structure1; Structure2; end structure Structure4 = Structure3 : SIG Admittedly, these are some pretty big structs, and poly's RAM usage hits over a gig, and doesn't go back down once execution is finished. "PolyML.fullGC ();" seems to have no effect. 3. Save the heap, still < 70 megs. 4. Close and open poly w new heap, RAM usage still < 70 megs So, the compile-time slowness seems to be poly filling the system's RAM and starts swapping pages. I included the code above on the off chance there's some cyclic dependency between the structs that keeps some junk from being garbage collected. I can give SVN links if you want to see the offending code itself, but its part of a pretty large project, so I don't know how helpful that would be. Thanks! Aleks

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Re: [MLton] bug to do with as-binding masking datatype constructor name
by matthew.fluet＠gmail.com 13 Apr '11

13 Apr '11

On Wed, Apr 13, 2011 at 2:49 AM, Andreas Rossberg <rossberg(a)mpi-sws.org> wrote: > On Apr 13, 2011, at 01:49, Michael Norrish wrote: >> >> Poly 5.3 rejects >> >> ?datatype foo = bar of string >> >> ?fun f x = let >> ? val bar as y = 3 >> ?in >> ? bar + x >> ?end >> >> MLton 20091212~svn accepts it. >> >> Who's right? > > Mlton, although this is arguably a design bug of the language. I was going to conclude that Poly/ML is right. I don't see why rule (43) applies to the "bar as y" pattern; it is not the case that "bar \notin Dom(C)" (because "bar" is in scope) and it is not the case that "is of C(vid) = v" (because "bar" has constructor status). MLton omits those two antecedents in its implementation of "as"-pattern elaboration. (Similarly, HaMLet omits them.) On the other hand, "val rec bar as y = fn() => 3" would allow changing the identifier status of "bar" (rule (26) and comment).

1 1

bug to do with as-binding masking datatype constructor name
by Michael.Norrish＠nicta.com.au 13 Apr '11

13 Apr '11

Poly 5.3 rejects datatype foo = bar of string fun f x = let val bar as y = 3 in bar + x end MLton 20091212~svn accepts it. Who's right? Best, Michael

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