While I was testing an unrelated issue, I discovered this: under
windows, with fpc 2.2.4, I try to start 10000 thread (I know it's absurd
but it's just a test) and have all of them linger around for 10 seconds.
The thread actually started are 121. The problem is that no exception is
raised, so how can I be sure that a thread is really started in a more
normal scenario? Is there a hard limit on the number of threads under
windows? If so, why no exception when I try to create more?
If I run the same program under Linux, an "EThread: failed to create new
thread" exception is raised after around 300 threads.
This is the test program
---------------8<-----------8<-------------8<------------------
program project1;
{$mode objfpc}{$H+}
uses
{$IFDEF UNIX}{$IFDEF UseCThreads}
cthreads,
{$ENDIF}{$ENDIF}
Classes, Sysutils, SyncObjs
{ you can add units after this };
var
Started:integer;
AccessStarted:TCriticalSection;
type
{ TMyThread }
TMyThread = class(TThread)
procedure Execute;override;
end;
procedure TMyThread.Execute;
begin
AccessStarted.Acquire;
Started:=Started+1;
AccessStarted.Release;
Sleep(10000);
end;
var i:integer;
{$IFDEF WINDOWS}{$R project1.rc}{$ENDIF}
begin
AccessStarted:=TCriticalSection.Create;
Started:=0;
for i:=1 to 10000 do
begin
TMyThread.Create(false);
writeln(i);
end;
while true do
begin
AccessStarted.Acquire;
writeln('Threads started:',started);
AccessStarted.Release;
Sleep(1000);
end;
end.
---------------8<-----------8<-------------8<------------------
If I remove the sleep(10000) (the writeln(i) should also be removed),
the number of threads started is a random
number, normally less than the 10000 expected, hence my deduction that
there's a hard limit on the number of threads (i.e. less threads hanging
around so more can be actually started).
Bye
--
Luca
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