Bugs item #1655670, was opened at 2007-02-09 02:08 Message generated for change (Comment added) made by sistisette You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=478070&aid=1655670...

Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: puredata Group: v0.40.2 Status: Open Resolution: None Priority: 5 Private: No Submitted By: Matteo Sisti Sette (sistisette) Assigned to: Nobody/Anonymous (nobody) Summary: misterious crashes when scripting

Initial Comment: Hi,

I'm sorry I can't be more specific. The attached patch makes PD crash.

Look at the patch, it has a lot of comments. I have reduced it to the minimum that I could.

I use messages to dinamically create and delete an object within a (sub)subpatch and connect it.

I pass a float "through" the subpatch when the dinamically created objects and connections are made so that it can pass through.

When doing a single iteration, that works. However, for some reason, if I put it into a loop (by feeding back the output to the input) it crashes. Note that the loop is not infinite, since I have a decrement and a condition to stop it after a number of iterations. It crashes even with a couple of iterations.

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Comment By: Matteo Sisti Sette (sistisette)

Date: 2007-02-10 16:37

Message: Logged In: YES user_id=1709568 Originator: YES

Thank you fbar, this explains better where the bug is and helps me isolating it in the following patch, which I attach as testbug4b.pd and which I reproduce here as it is very simple: [bng] | [f] | [find f, cut( | [s pd-testbug4b.pd]

(assuming the file is saved as testbug4b.pd)

However, I think this still is a bug. 1) First, because whenever a program crashes it is a bug, no matter how incorrect the input (in this case the patch).

2) Secondly, because I don't see what is semantically wrong about deleting the [f] even if the message that deletes it has been originated by itself. That is an implementation issue. Let's look at the flux of data, or messages. [f] outputs a message that is a float. This message hits the message box and causes it to output two messages: -a "find f", which reaches the [s], is sent to the canvas, and causes the [f] to be selected -a "cut", which reaches the [s], is sent to the canvas, and causes the [f] to be deleted. ...so what?

If, internally, the flux of data is tracked somewhere "inside" the object that originates it, it is a matter of implementation that the patch author need not care about. And that is an implementation that doesn't completely take into account the possibility that objects may dynamically be deleted. File Added: testbug4b.pd

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Comment By: Frank Barknecht (fbar) Date: 2007-02-10 01:21

Message: Logged In: YES user_id=569446 Originator: NO

This actually is a "I shoot myself in the foot to commit suicide" bug in the patch. ;)

What is happening here: After triggering the "30" the [t f f b] in [pd one] will first delete the [f] in [pd two] and then recreate it. This is okay. Then the 30 will be sent from the middle outlet of the [t f f b] and open the spigot. From the left outlet of [t f f b] it will then be decremented to 29 and go into [pd two] where it is passed through the [f]. This moment is important so lets mark it with <crash-reason>. The 29 will then leave [pd two] and after that leave [pd one] as well, go through the outside [t f f] and enter [pd one] again.

Now as it reaches [t f f b] in [pd one] again, where it will again first initiate the bang that cuts the [f] in [pd two]. But now the problem occurs: In the past at time <crash-reason> the [f] in [pd two] was, what was triggering the second time, the [f] in [pd two] should be deleted, so to Pd this is a case of suicide: The [f] object is trying to delete itself and that's illegal. It's not a bug in Pd - although Pd shouldn't crash - it's more a bug in the patch.

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