Squeak-dev August 2007

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132 participants
163 discussions

How to generate identically image file after snapshots
by Martin Troielli 02 Aug '07

02 Aug '07

Hi All, We have tried to produce the same (bit identically) image file after two consecutive snapshots. We start from a base image then, fileIn several files into it and finally, we just SmalltalkImage current snapshot: true andQuit: true. We need this to verify the image file generated by a third-party with a checksum by executing a script. After trying several ways to get it (even by scripting the fileIn process and the snapshot), we found that the image files have, beside the timestamp differences, thousands of other differences and sometimes the snapshots have also size differeces. We supose that this kind of issues may occur due to the GC activity. Are this issues from the way GC process is changing dynamically the memory bytes? There is a way to inhibite this activity? Attached are the scripts we use to produce the image files. Many thanks in advance, Martin Troielli

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How do we get a string with a specific encodings
by stephane ducasse 02 Aug '07

02 Aug '07

Hi guys I would like to know how I can specify the encodings of my strings. Stef

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Re: About pushBack:
by stephane ducasse 02 Aug '07

02 Aug '07

On 2 août 07, at 15:37, stéphane ducasse wrote: > > On 2 août 07, at 15:31, Michael Rueger wrote: > >> stéphane ducasse wrote: >>> Hi Mike >>> we are heroically trying to clean Stream hierarchy (in fact >>> making sure that the new and sexy one that damien is writing can >>> be plugged in). >>> We are reading >>> PositionableStream>>pushBack: aString >>> "Compatibility with SocketStreams" >>> self skip: aString size negated >>> and it seems to me that pushBack argument is not good. It should >>> not be a string but a number since >>> it never take care of pushing back different elements in the >>> stream but just moving the cursor of the stream. >> >> Yes, but... >> On a SocketStream we can't position the cursor, once the >> characters are read they are no longer in the stream as there is >> no underlying collection. The buffer doesn't count, as the content >> can be replaced at any time during read or write. > > So? I'm confused :) > Do you need the argument or just its size? >> >>> Do you know if the method pushBack on the XMLTokenizer is ever used? >> >> It's used when parsing and resolving entity definitions. > > > I put a breakpoint on XMLTokenizer>>pushBack: and run XMLDOMParser > addressBookXMLWithDTD > but I was not stopped. > > While unpeek is calling the PositionableStream>>pushBack: via > unpeek. I could not see where XMLTokenizer>>pushBack: is invoked. > > > unpeek > > peekChar > ifNotNil: [ > self stream pushBack: (String with: peekChar). > peekChar _ nil] > > Thanks for your fast answer. > > stef >

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About Stream>>write:
by Damien Cassou 02 Aug '07

02 Aug '07

What is the desired behavior of Stream>>write:? The implementation is: Stream>>write:encodedObject ^ encodedObject putOn:self. and there are 2 implementors of #putOn: Object>>putOn:aStream ^ aStream nextPut:self. String>>putOn:aStream ^ aStream nextPutAll: self. Is there a need for such a method? Now, if I look at some of the senders, I find: Bitmap>>printOnStream: aStream aStream print: 'a Bitmap of length '; write: self size. Color:byteEncode: aStream aStream print: '('; print: self class name; print: ' r: '; write: (self red roundTo: 0.001); Rectangle>>propertyListOn: aStream aStream print:'{ x='; write:origin x; In nearly all the senders, a number is passed to #write:. But if it's a number, then #nextPut: will be sent to the stream with the number as argument. And if you have a stream of characters, as it is the case here because strings are printed to the stream, you can't write numbers directly. Try: stream := ReadWriteStream on: String new. Color red byteEncode: stream. Bitmap allInstances anyOne printOnStream: stream. it will fail on 3.7, 3.8 and 3.9. What is the real aim of #write: and how is it different from #print:? -- Damien Cassou

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Looking for Yaxo (unit) tests
by stephane ducasse 02 Aug '07

02 Aug '07

Hi I would like to know whether there are some unit tests for Yaxo? Stef PS: this would be a nice package to have with tests.

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Box-Admins Team Report for July, 2007
by Ken Causey 02 Aug '07

02 Aug '07

The box-admins team is reponsible for seeing that the community shared server is maintained and setting up any new features to be hosted on that server. For July 2007: Adrian Lienhard kindly upgraded the version of SqueakSource and its dependencies on source.squeakfoundation.org. I want to thank the community for the monetary support needed to fund the box and remind them that the bills continue to appear and that you can currently contribute to the hosting bills by going to http://discuss.squeakfoundation.org/ and clicking on the 'donate' button at the top right. Note that a donation here may be used for other Squeak Foundation services including but not limited to development, development infrastructure, and promotion of Squeak. The services being hosted have continued to grow and include (but are not limited to): http://www.squeak.org/ SqueakMap - http://map.squeak.org/ http://ftp.squeak.org/ http://lists.squeakfoundation.org/ http://discuss.squeakfoundation.org/ http://source.squeakfoundation.org/ http://map.squeak.org/ https://svn.squeak.org/ http://update.squeakfoundation.org/ http://wiki.squeak.org/ http://bugs.squeak.org/ and DNS services for squeak.org and squeakfoundation.org domain names. Ken

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Symbol allInstances
by Philippe Marschall 02 Aug '07

02 Aug '07

Hi Browsing through a 3.9 image I found three senders of Symbol allInstances which store the result in a temp during image segment export: ImageSegment >> #copySmartRootsExport: CodeLoader >> #exportCodeSegment:classes:keepSource: SystemDictionary >> #writeImageSegmentsFrom:withKernel: Is this a problem? Cheers Philippe

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Mantis down
by Adrian Lienhard 02 Aug '07

02 Aug '07

http://bugs.squeak.org does not respond anymore. I can ping box2.squeakfoundation.org though. Adrian

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Delay and Server reliability
by Andreas Raab 02 Aug '07

02 Aug '07

Hi - We recently had some "fun" chasing server lockups (with truly awful uptimes of about a day or less before things went downhill) and were finally able to track a huge portion of it down to problems with Delay. The effect we were seeing on our servers was that the system would randomly lock up and either go down to 0% CPU or 100% CPU. After poking it with a USR1 signal (which, in our VMs is hooked up such that it prints all the call stacks in the image; it's a life-safer if you need to debug these issues) we usually found that all processes were waiting on Delay's AccessProtect (0%) or alternatively found that a particular process (the event tickler) would sit in a tight loop swallowing repeated errors complaining that "this delay is already scheduled". After hours and hours of testing, debugging, and a little stroke of luck we finally found out that all of these issues were caused by the fact that Delay's internal structures are updated by the calling process (insertion into and removal from SuspendedDelays) which renders the process susceptible to being terminated in the midst of updating these structures. If you look at the code, this is obviously an issue because if (for example) the calling process gets terminated while it's resorting SuspendedDelays the result is unpredictable. This is in particular an issue because the calling process is often running at a relatively low priority so interruption by other, high-priority processes is a common case. And if any of these higher priority processes kills the one that just happens to execute SortedCollection>>remove: anything can happen - from leaving a later delay in front of an earlier one (one of the cases we had indicated that this was just what had happened) to errors when doing the next insert/remove ("trying to evaluate a block that is already evaluated") to many more weirdnesses. Unfortunately, it is basically impossible to recreate this problem under any kind of controlled circumstances, mostly because you need a source of events that is truly independent from your time source. As a consequence of our findings we rewrote Delay to deal with these issues properly and, having deployed the changes about ten days ago on our servers, all of these sources of problems simply vanished. We haven't had a single server problem which we couldn't attribute to our own stupidity (such as running out of disk space ;-) The changes will in particular be helpful to you if you: * run network servers * fork processes to handle network requests * terminate these processes explicitly (on error conditions for example) * use Semaphore>>waitTimeoutMsecs: (all socket functions use this) If you have seen random, unexplained lockups of your server (0% CPU load while being locked up is a dead giveaway[*]) I'd recommend using the attached changes (which work best on top of a VM with David Lewis' 64bit fixes applied) and see if that helps. For us, they made the difference between running the server in Squeak and rewriting it in Java. I've also filed this as http://bugs.squeak.org/view.php?id=6576 [*] The 0% CPU lockups have sometimes been attributed to issues with Linux wait functions. After having seen the havoc that Delay wrecks on the system I don't buy these explanations any longer. A much simpler (and more likely) explanation is that Delay went wild. Cheers, - Andreas

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About PositionableStream class>>on:from:to
by Damien Cassou 02 Aug '07

02 Aug '07

Hi, I do not understand the behavior of #on:from:to: (ReadStream on: 'abcdefgh' from: 4 to: 7) contents. ==> 'abcdefg' "really strange" (PositionableStream on: 'abcdefgh' from: 4 to: 7) contents. ==> 'defg' "which sounds normal to me" And PositionableStream is an abstract class whereas ReadStream is concrete. -- Damien Cassou

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