Calling library within TThread
lazarus / 32-Linux

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piola · 2015-12-30 11:18

I have some strange issue using a library function within a thread.
Please have a look at the following minimal example codes:

Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i library
library1; {$mode objfpc}{$H+} uses  cthreads; procedure test (var
result: integer); stdcall;begin  result:=42;end; exports 
test; beginend. 
Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
project1; uses  cthreads,  classes,  dynlibs; type  ttestproc =
procedure (var result: integer); stdcall;  tmythread = class(tthread) 
  procedure execute; override;    protected    h: tlibhandle;    f:
ttestproc;  end; procedure tmythread.execute;var i: integer;begin  h
:= loadlibrary ('./liblibrary1.so');  f := ttestproc
(getprocedureaddress (h, 'test'));  f(i);  unloadlibrary(h);end; var 
t:  tmythread;  h1: tlibhandle; begin  h1 := loadlibrary
('./liblibrary1.so');  t := tmythread.create(true);  t.start; 
t.waitfor;  unloadlibrary (h1);end. 
I have a library which has to be held in memory; therefore it's
initialized in the main thread and released only when the main thread
finishes. Functions within the library have to be called within child
threads. The code works well on Windows32 and on Linux64.

However, on Linux32, with the "Stack Overflow checking" activated when
compiling the library, a Stack Overflow Error 202 occurs in the call
of the library function in line 22 of the main program. Note that this
problem only arises when
a) The library has already been loaded before (line 31), and
b) when it's executed within a thread. Replace t.start in line 33 with
t.execute, and everything is fine.

It would be kind if someone could tell me whether I have made a
mistake in programming or if this problem is du a compiler bug.

Tested on Ubuntu 15.10, Lazarus 1.4, FPC 2.6.4.