<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=US-ASCII"> <META content="MSHTML 6.00.2900.5969" name=GENERATOR></HEAD> <BODY id=role_body style="FONT-SIZE: 10pt; COLOR: #000000; FONT-FAMILY: Arial" bottomMargin=7 leftMargin=7 topMargin=7 rightMargin=7><FONT id=role_document face=Arial color=#000000 size=2> <DIV>For one of problems Greg has reported in his earlier emails: that DrRacket can be crashed even when a memory limit is set, I've seen this as well, fairly commonly on Windows XP and Vista with v4.x and now v5.0.</DIV> <DIV> </DIV> <DIV>If it is of any use, I can consistently reproduce this on my XP netbook, with the following (toy) program using v5.0.</DIV> <DIV> </DIV> <DIV>#lang scheme</DIV> <DIV> </DIV> <DIV>(define (go [n 0] [foo '()])<BR>  (go (+ n 1) (cons (build-vector 1000000 (lambda (n) (make-string n #\a))) foo)))</DIV> <DIV> </DIV> <DIV>(go)</DIV> <DIV> </DIV> <DIV> </DIV> <DIV>I just click the "Run" button, and wait for bad things to happen... I first get an error message stating "Racket Virtual Machine is out of memory. Aborting". Then I get a Microsoft Visual C++ Runtime Library dialog box indicating a runtime error, where the "application has requested the Runtime to terminate it in an unusual way". Finally, I get a dialog box reporting that "Racket GUI application has encountered a problem and needs to close.  We are sorry for the inconvenience.", and offering to send a report to Microsoft.</DIV> <DIV> </DIV> <DIV>For sure, I can reproduce this when I have the memory limit set to 1024 MB or 2048 MB. So far I have been able to reproduce this with the memory limit set to >= 750 MB. At 512MB, the memory limit correctly kicks, and I get a DrRacket error message, but DrRacket does not crash.</DIV> <DIV> </DIV> <DIV>Curiously, when the memory limit is set to 700MB, I get a different error message. I don't get the dialog box about exceeding the memory limit; DrRacket gives an "out of memory" error in the interactions panel, but does not crash.</DIV> <DIV> </DIV> <DIV>I've just retested with the latest nightly build [<EM>Welcome to DrRacket, version 5.0.0.9--2010-07-14(d162667/a) [3m].] </EM>and gotten the same results. With the latest nightly build, I can reproduce the crash with a memory limit as low as 650 MB. (At a memory limit of 600MB, the memory limit error dialog did kick in, with no crash.)</DIV> <DIV> </DIV> <DIV>My impression is that memory usage, as reported by the Windows Task Manager, is not even close to the memory limit at the time of the crash (e.g. <200MB, or even much smaller).</DIV> <DIV> </DIV> <DIV>Jim</DIV> <DIV> </DIV> <DIV> </DIV> <DIV> <DIV>In a message dated 7/14/2010 5:23:06 P.M. Central Daylight Time, greghendershott@gmail.com writes:</DIV> <BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT style="BACKGROUND-COLOR: transparent" face=Arial color=#000000 size=2>Good news, I found and fixed my memory over-consumption, albeit the hard way.<BR><BR>Some take-aways:<BR><BR>[1] I remain convinced that DrRacket won't use > 1 GB for on Win64.<BR>[2] It would be great to see DrRacket as a full 64 bit app on Windows<BR>and Mac OS X someday.<BR>[3] The intended use of Limit Memory and its interaction with actual<BR>memory available from the OS, could use some better doc/explanation.<BR>It will suggest you increase its limit when you hit, but on the list<BR>I'm learning that can backfire, and anyway I've seen the limit ignored<BR>... basically it's all pretty confusing.<BR>[4] More memory debugging tools would be helpful, as it's non-trivial<BR>to correlate Racket data to bytes (e.g. no C-style sizeof).<BR>[5] I learned that some of you seemingly don't use the DrRacket<BR>environment very much, yourselves? :)<BR>[6] Speaking of DrRacket and debugging, the debugger needs an option<BR>to limit the display of large items; otherwise DrRacket becomes very<BR>unresponsive and stepping in the debugger can take many, many seconds<BR>between each step. Debugging = pain is the wrong lesson to teach new<BR>folks IMHO.<BR>[7] Although DrRacket is already a good "IDE", many people know stuff<BR>like Eclipse and Visual Studio, and this is a big part of the<BR>experience of the "language" and important for broader acceptance<BR>(assuming that's a priority?).<BR><BR>Sorry if that's a random brain-dump but I hope it may be helpful. Also<BR>I hope it's clear that if I didn't like Racket I wouldn't bother<BR>offering the feedback, so although this may not feel like a<BR>compliment, indirectly it is. :)<BR><BR>Cheers,<BR>Greg<BR><BR>On Tue, Jul 13, 2010 at 8:40 PM, Robby Findler<BR><robby@eecs.northwestern.edu> wrote:<BR>> On Tue, Jul 13, 2010 at 6:39 PM, Greg Hendershott<BR>> <greghendershott@gmail.com> wrote:<BR>>> OK mister smartypants. :)<BR>><BR>> Indeed! :)<BR>><BR>>> I set the limit back to 1024 MB.<BR>>><BR>>> And ... it crashed again DrRacket again.<BR>><BR>> That limit is probably high enough to be ineffective as an actual<BR>> limit. I don't understand the precise connection between what<BR>> current-memory-use reports and what the OS says that a process is<BR>> using, but you want to use the numbers for the former, not the latter.<BR>><BR>>> Just like it did back when I decided to try setting it to "unlimited"<BR>>> in the first place, to avoid this happening.<BR>>><BR>>> Seriously, is the idea that users are supposed to:<BR>>> [1] Understand the maximum memory for their system. (Which isn't<BR>>> documented, but on Win64 is 2 GB ... unless it is actually 1 GB.)<BR>>> [2] Set the DrRacket memory limit to whatever value they guessed in step 1.<BR>>> [3] Watch DrRacket abend and lose their work, anyway?<BR>>><BR>>> I'm not trying to be a PITA, I genuinely don't understand the intended usage.<BR>>><BR>>> Also I guess I'm frustrated that I have a memory utilization issue<BR>>> which is my own darn fault, but I have no clear mental model, yet,<BR>>> what the heck is happening and how to track it down. In which regard I<BR>>> suppose I feel like an Alan Perlis punch-line: A programmer who knows<BR>>> the value, and actually DOES want to understand the cost ... but<BR>>> can't. Like, if I have to ask the price, I can't afford it ... ?<BR>><BR>> ha!<BR>><BR>> IMO, we are missing good memory debugging tools, but this is a big<BR>> project so likely you'll have to stick with what we have so far.<BR>><BR>> If you build with one of the alternate collects (sgc?) you can get a<BR>> fair amount of memory debugging information. Its pretty low-level and<BR>> there is no visualization to help you understand, but if you are<BR>> careful and think hard about what it is telling you, you might be able<BR>> to get some use out of it.<BR>><BR>> Robby<BR>><BR>_________________________________________________<BR>  For list-related administrative tasks:<BR>  http://lists.racket-lang.org/listinfo/users<BR></FONT></BLOCKQUOTE></DIV></FONT></BODY></HTML>