Thread never executed?
lazarus / 43-Android

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Halbi1 · 2015-07-18 22:32

Hello,

I am old Delphi (1 and 2) programmer and after more than a decade I
found Lazarus to continue with my old project electronic interlocking
for railroad modelists on Windows.
The application developed on an old Windows 2000 Laptop with Lazarus
1.2.2 runs on several PCs with XP and Windows 7.

Now I try to find out if my application can be ported to an android
tablet or smartphone. I found the latest LazToApk 0.9.0.31, I managed
to create the demo app 'project1' and it works. After these Buttons
and Labels I tried to do something with a Canvas and it works. After
having done a mess with the Lnet-Component I found the Synapse units
and that sending Strings is a very easy thing to do, but now I have to
realise a thread for receiving messages (copied and modified from
Lazarus Multi threading tutorial). On Win2000 it works, but on the
Android Device (Samsung S3 , Android 4.1.2) it seems that the thread
method 'Execute' is never - eh - executed.
Because the app don't crash I can not see any helpful information in
the adb log except that the app dies.
Any ideas or hints? Thanks in advance.

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Leledumbo · 2015-07-19 10:51

I see no cthreads in the uses clause. Under *nix platforms, you need
cthreads because the platform doesn't provide native threading support
which FPC can load automatically. See:
http://wiki.lazarus.freepascal.org/Lazarus_Faq#When_I_run_a_program_wi
th_threads_I_get_runtime_error_232
http://wiki.lazarus.freepascal.org/Multithreaded_Application_Tutorial#
Units_needed_for_a_multi-threaded_application

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Halbi1 · 2015-07-19 14:44

Thanks to Leledumbo. In the meantime I found the hint to cthreads in a
Post from greenzyzyzy
http://forum.lazarus.freepascal.org/index.php/topic,28344.0.html, but
it has to be placed in the use clause of the *.lpr file. In the use
clause of the main unit the application crashes.

Another hint I found in http://lazarus-
dev.blogspot.de/2013/08/threads-with-lazarus.html:
'If you use threading in your program you should define the compiler
option -dUseCThreads.'

But its still the same: The procedure Execute seems to be never
executed.

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Leledumbo · 2015-07-19 18:34

Quote from: Halbi1 on July 19, 2015, 04:44:38 pmThanks to Leledumbo.
In the meantime I found the hint to cthreads in a Post from
greenzyzyzy
http://forum.lazarus.freepascal.org/index.php/topic,28344.0.html, but
it has to be placed in the use clause of the *.lpr file. In the use
clause of the main unit the application crashes.
It's explained so in at least one of the link above. Didn't you see?
Quote from: Halbi1 on July 19, 2015, 04:44:38 pmAnother hint I found
in http://lazarus-dev.blogspot.de/2013/08/threads-with-lazarus.html:
'If you use threading in your program you should define the compiler
option -dUseCThreads.'

But its still the same: The procedure Execute seems to be never
executed.
No, you don't need that. It's required ONLY AND IF ONLY you use the
default application project, because of the .lpr template (see
yourself how it looks like).