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| ID | Category | Severity | Reproducibility | Date Submitted | Last Update | |||||||
| 0002149 | [Squeak] System | major | always | 11-02-05 10:37 | 11-03-05 20:20 | |||||||
| Reporter | renggli | View Status | public | |||||||||
| Assigned To | ||||||||||||
| Priority | normal | Resolution | open | |||||||||
| Status | new | Product Version | 3.7 | |||||||||
| Summary | 0002149: Accessing source-code is not thread-save | |||||||||||
| Description | If two processes concurrently access the source code of a method they might get an invalid string that cannot be compiled. This leads to a wide range of different bugs, the one most often visible is a syntax that pops up within the image (see attached screen-shot). This is especially annoying if Squeak is used within a server environment. | |||||||||||
| Additional Information | ||||||||||||
| Attached Files |
 syntax-error.png [^] (7,785 bytes) 11-02-05 10:37 SourceCodeAccessTest.st [^] (1,491 bytes) 11-02-05 11:01 |
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Notes |
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(0003021 - 450 - 450 - 450 - 450 - 450 - 450) renggli 11-02-05 11:26 |
Ahh, I just happened to experience another prove of this particular problem: When having the process-browser open, auto update turned on, and having selected a particular process, this bug is observable again: browse around within your image, if you are 'lucky' you can see the code-browser actually load a incomplete method OR (what is more likely) the process browser will show a syntax-error morph as stated above when trying to display the stack. |
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(0003022 - 734 - 758 - 758 - 758 - 758 - 758) tim 11-02-05 19:11 |
This isn't particularly related to source code though; more a general problem with the whole file accessing system. Unfortunately, Squeak uses one primitive to position the 'current pointer' for an open file and another to read x bytes from the current pointer. Obviously if multiple threads are working on the same file there is a reasonable chance that at some time the position and read/write will interleave and screw up your day. The same problem is there in many low level OS libraries - Squeak just copied the model in the ANSI C stdio.h standard. I always did think it was pretty stupid. A read/write(file, pos, numbytes) is much safer. It's one of the things that needs to be tackled by the File Team. Yet another.... |
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(0003023 - 248 - 333 - 333 - 333 - 333 - 333) tim 11-02-05 19:11 |
From Craig (latta@netjam.org) Tim writes: > A read/write(file, pos, numbytes) is much safer. The filesystem support in Flow[1] does this, for example. Flow provides a complete replacement for the current filesystem framework, by the way. |
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(0003026 - 88 - 88 - 88 - 88 - 88 - 88) sam 11-03-05 20:20 |
On platforms where mmap() is available, it would be easy to implement such a method set. |
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Issue History |
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| Date Modified | Username | Field | Change |
| 11-02-05 10:37 | renggli | New Issue | |
| 11-02-05 10:37 | renggli | File Added: syntax-error.png | |
| 11-02-05 10:53 | renggli | Issue Monitored: renggli | |
| 11-02-05 11:01 | renggli | File Added: SourceCodeAccessTest.st | |
| 11-02-05 11:26 | renggli | Note Added: 0003021 | |
| 11-02-05 19:11 | tim | Note Added: 0003022 | |
| 11-02-05 19:11 | tim | Note Added: 0003023 | |
| 11-03-05 20:20 | sam | Note Added: 0003026 | |
| 12-10-05 15:32 | pmm | Issue Monitored: pmm | |
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