Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 16/02/2016 10:04, Michael Schnell ha scritto: a (potential) bug (in "Glib2" whatever this exactly means) Glib2 means version 2 of GTK Glib, which is used by Qt (and by GTK) to implement the main event loop. libglib-2.0.so.0 The full picture (from stack trace) is as follows: 1. The main

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 16/02/2016 10:04, Michael Schnell ha scritto: Anyway, IMHO it's not a good idea to fight a (potential) bug (in "Glib2" whatever this exactly means) by implementing a completely queer behavior in Application.ProcessMessage. I fully agree with you. Seeing a unexpected recursion, I had

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/15/2016 07:23 PM, Giuliano Colla wrote: The result is to make Application.ProcessMessage not 100% reentrant, because of a Glib2 bug. Would you suggest not to handle "the same" event ? How should you detect that its the event already in the works or the next occurrence ? In the

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 15/02/2016 11:54, Michael Schnell ha scritto: On 02/13/2016 12:27 PM, Giuliano Colla wrote: At least under Qt widgetset, it may happen that calling Application.ProcessMessages from within a Message Handler will cause the same message which was being processed to be processed again, the

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/13/2016 12:27 PM, Giuliano Colla wrote: At least under Qt widgetset, it may happen that calling Application.ProcessMessages from within a Message Handler will cause the same message which was being processed to be processed again, the handler called again and

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 12/02/2016 15:35, Michael Schnell ha scritto: On 02/12/2016 03:17 PM, Mattias Gaertner wrote: IMHO, Michael, you should not redefine words. It confuses people. Reentrant means it can be called again, while it is still running. It does not need to be thread-safe. Sorry that was not me.

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/12/2016 03:17 PM, Mattias Gaertner wrote: IMHO, Michael, you should not redefine words. It confuses people. Reentrant means it can be called again, while it is still running. It does not need to be thread-safe. Sorry that was not me. The subject here is " thread save " ,so I

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/10/2016 10:12 PM, C Western wrote: My understanding is Application.ProcessMessages has to be reentrant ... As calling Application.ProcessMessages is only allowed from the main thread it does not need to be reentrant = thread-save. Of course it can be called recursively and it hence

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On Fri, 12 Feb 2016 14:53:29 +0100 Michael Schnell wrote: > On 02/10/2016 10:12 PM, C Western wrote: > > > > My understanding is Application.ProcessMessages has to be reentrant ... > > As calling Application.ProcessMessages is only allowed from the main > thread it does not

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 21:13, Giuliano Colla ha scritto: I don't believe that there's an easy way to protect Application.ProcessMessages from recursion unless someone is willing to debug and patch Glib (which is used not only by Qt, but also from GTK, if I'm not wrong). A snippet from gmain.c: #if 0

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 13:48, zeljko ha scritto: I believe that Application.ProcessMessages should protect itself too, avoiding to handle more than once the same message. But where ? In LCL or per widgetset ? I skimmed through the backtrace. It would appear that the recursion originates in

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 10/02/16 20:13, Giuliano Colla wrote: Il 10/02/2016 13:48, zeljko ha scritto: I believe that Application.ProcessMessages should protect itself too, avoiding to handle more than once the same message. But where ? In LCL or per widgetset ? I skimmed through the backtrace. It would appear

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 00:18, Denis Kozlov ha scritto: Is your LM_ERROR larger than LM_USER? Yes : const LM_ANSWER= LM_USER + 100; LM_MESSAGE = LM_USER + 101; LM_ERROR = LM_USER + 102; Giuliano -- ___ Lazarus mailing list

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 00:22, Denis Kozlov ha scritto: You create a recursive scenario yourself by calling Application.ProcessMessages inside of ShowError inside of HandleError - which is the message handling procedure itself, which is triggered by Application.ProcessMessages. That's what I had

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 08:44, zeljko ha scritto: 1.Your ErrList access does not look thread safe. It's a poor man's thread safe queue, implemented as a ring buffer, with two indexes, ErrGet and ErrPut. It's fully safe, provided the buffer is guaranteed not to overflow, and that ErrPut is updated only

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/10/2016 11:19 AM, Giuliano Colla wrote: This I believe to be the problem. From the observations from Denis I realized that my code isn't protected against recursion, but I believe that Application.ProcessMessages should protect itself too, avoiding to handle more than once the same

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 12:31, zeljko ha scritto: On 02/10/2016 11:19 AM, Giuliano Colla wrote: This I believe to be the problem. From the observations from Denis I realized that my code isn't protected against recursion, but I believe that Application.ProcessMessages should protect itself too, avoiding

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/10/2016 12:48 PM, Giuliano Colla wrote: Il 10/02/2016 12:31, zeljko ha scritto: On 02/10/2016 11:19 AM, Giuliano Colla wrote: This I believe to be the problem. From the observations from Denis I realized that my code isn't protected against recursion, but I believe that

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

Il 10/02/2016 22:12, C Western ha scritto: My understanding is Application.ProcessMessages has to be reentrant for the clipboard to work, at least under X, as clipboard content is retrieved by receiving messages. See http://bugs.freepascal.org/view.php?id=26242 for a (fixed) bug that showed

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 09/02/2016 22:37, Giuliano Colla wrote: PostMessage(Form1.Handle,LM_ERROR,Integer(ErrPut),0); Is your LM_ERROR larger than LM_USER? PostMessage is thread safe. -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

You create a recursive scenario yourself by calling Application.ProcessMessages inside of ShowError inside of HandleError - which is the message handling procedure itself, which is triggered by Application.ProcessMessages. -- ___ Lazarus mailing

Re: [Lazarus] Lazarus application crash. Is PostMessage thread safe?

On 02/09/2016 11:37 PM, Giuliano Colla wrote: Hi Lazarus guru's, I have stumbled into a problem with a Lazarus application. At random times, from 5 minutes to several hours, it crashes suddenly, and silently. The only way to get a clue has been to run it with gdb. It turns out that the crash